/* ============================================================
   MENTALNAYA-ARIFMETIKA.RU — Main Stylesheet
   ============================================================ */

/* ---------- RESET & TOKENS ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue-50:  #eff6ff;
  --blue-100: #dbeafe;
  --blue-500: #3b82f6;
  --blue-600: #2563eb;
  --blue-700: #1d4ed8;
  --blue-800: #1e40af;

  --green-50:  #f0fdf4;
  --green-500: #22c55e;
  --green-600: #16a34a;

  --red-50:  #fef2f2;
  --red-400: #f87171;
  --red-500: #ef4444;

  --orange-400: #fb923c;
  --orange-500: #f97316;

  --amber-400: #fbbf24;
  --amber-500: #f59e0b;

  --purple-500: #a855f7;
  --cyan-500:   #06b6d4;

  --gray-50:  #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;

  --shadow-sm: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.05);
  --shadow:    0 4px 6px -1px rgba(0,0,0,.1), 0 2px 4px -2px rgba(0,0,0,.07);
  --shadow-md: 0 10px 15px -3px rgba(0,0,0,.1), 0 4px 6px -4px rgba(0,0,0,.07);
  --shadow-lg: 0 20px 25px -5px rgba(0,0,0,.1), 0 8px 10px -6px rgba(0,0,0,.07);

  --radius-sm: 6px;
  --radius:    10px;
  --radius-lg: 16px;
  --radius-xl: 24px;

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --transition: 150ms ease;
}

html { scroll-behavior: smooth; overflow-x: hidden; }

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--gray-800);
  background: #fff;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

a { color: var(--blue-600); text-decoration: none; }
a:hover { color: var(--blue-700); }
img { max-width: 100%; display: block; }
ul { list-style: none; }

/* ---------- LAYOUT ---------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section { padding: 4.5rem 0; }
.section-alt { background: var(--gray-50); }

.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  color: var(--gray-900);
  text-align: center;
  margin-bottom: 2.5rem;
}
.section-subtitle {
  text-align: center;
  color: var(--gray-500);
  margin-top: -.5rem;
  margin-bottom: 2.5rem;
  font-size: 1.05rem;
}
.section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 2rem;
}
.section-header .section-title { margin-bottom: 0; }
.section-more { color: var(--blue-600); font-weight: 600; font-size: .95rem; white-space: nowrap; }
.section-more:hover { color: var(--blue-800); }

/* ---------- BUTTONS ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .4rem;
  padding: .625rem 1.25rem;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  transition: background var(--transition), color var(--transition),
              border-color var(--transition), transform var(--transition), box-shadow var(--transition);
  white-space: nowrap;
  text-decoration: none;
  line-height: 1.3;
}
.btn:active { transform: translateY(1px); }

.btn-primary {
  background: var(--blue-600);
  color: #fff;
  border-color: var(--blue-600);
}
.btn-primary:hover {
  background: var(--blue-700);
  border-color: var(--blue-700);
  color: #fff;
  box-shadow: 0 4px 12px rgba(37,99,235,.35);
}

.btn-cta {
  background: var(--orange-500);
  color: #fff;
  border-color: var(--orange-500);
}
.btn-cta:hover {
  background: #ea6c08;
  border-color: #ea6c08;
  color: #fff;
  box-shadow: 0 4px 12px rgba(249,115,22,.35);
}

.btn-ghost {
  background: transparent;
  color: var(--gray-700);
  border-color: var(--gray-300);
}
.btn-ghost:hover {
  background: var(--gray-100);
  border-color: var(--gray-400);
  color: var(--gray-900);
}

.btn-outline {
  background: transparent;
  color: #fff;
  border-color: rgba(255,255,255,.6);
}
.btn-outline:hover {
  background: rgba(255,255,255,.1);
  border-color: #fff;
  color: #fff;
}

.btn-lg  { padding: .8rem 1.75rem; font-size: 1rem; }
.btn-xl  { padding: 1rem 2rem; font-size: 1.05rem; }
.btn-full { width: 100%; }

/* ---------- HEADER ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--gray-200);
  padding: .75rem 0;
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: .6rem;
  text-decoration: none;
  color: var(--gray-900);
  flex-shrink: 0;
}
.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--blue-600);
  color: #fff;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 900;
  line-height: 1;
}
.logo-text {
  font-size: .8rem;
  line-height: 1.3;
  color: var(--gray-600);
}
.logo-text strong { color: var(--gray-900); font-size: .9rem; }

.nav-links {
  display: flex;
  align-items: center;
  gap: .25rem;
}
.nav-link {
  padding: .45rem .9rem;
  border-radius: var(--radius-sm);
  color: var(--gray-600);
  font-size: .95rem;
  font-weight: 500;
  transition: background var(--transition), color var(--transition);
}
.nav-link:hover { background: var(--gray-100); color: var(--gray-900); }
.nav-link-course {
  background: var(--orange-500);
  color: #fff !important;
  padding: .45rem 1rem;
}
.nav-link-course:hover { background: #ea6c08; color: #fff; }

/* Nav dropdown */
.nav-dropdown-wrap { position: relative; }
.nav-dropdown-trigger {
  background: none;
  border: none;
  font-family: inherit;
  cursor: pointer;
}
.nav-dropdown {
  position: absolute;
  top: 100%;
  left: 0;
  margin-top: .25rem;
  min-width: 200px;
  background: #fff;
  border-radius: var(--radius);
  box-shadow: 0 4px 12px rgba(0,0,0,.12);
  padding: .5rem 0;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: opacity .15s ease, transform .15s ease, visibility .15s;
  z-index: 200;
}
.nav-dropdown.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.nav-dropdown-item {
  display: block;
  padding: .5rem 1rem;
  color: var(--gray-700);
  font-size: .9rem;
  text-decoration: none;
  transition: background .1s;
}
.nav-dropdown-item:hover { background: var(--gray-100); color: var(--gray-900); }

.nav-dropdown-sep {
  height: 1px;
  background: var(--gray-200);
  margin: .4rem 0;
  list-style: none;
}

/* Trainer nav adjacent (Проще / Сложнее) */
.trainer-nav-adjacent { margin-left: .5rem; }
.trainer-nav-link { color: var(--blue-600); text-decoration: none; font-weight: 500; }
.trainer-nav-link:hover { text-decoration: underline; }
.trainer-nav-prev::before, .trainer-nav-next::after { content: none; }
.trainer-nav-sep { color: var(--gray-400); margin: 0 .35rem; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--gray-700);
  border-radius: 2px;
  transition: var(--transition);
}

/* ---------- HERO ---------- */
.hero {
  padding: 4rem 0 3rem;
  overflow: hidden;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.hero-badge {
  display: inline-block;
  background: var(--blue-50);
  color: var(--blue-700);
  border: 1px solid var(--blue-100);
  padding: .3rem .85rem;
  border-radius: 999px;
  font-size: .85rem;
  font-weight: 600;
  margin-bottom: 1.25rem;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 900;
  line-height: 1.15;
  color: var(--gray-900);
  margin-bottom: 1.25rem;
}

.gradient-text {
  background: linear-gradient(135deg, var(--blue-600), var(--purple-500));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--gray-600);
  margin-bottom: 2rem;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  gap: .75rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}

/* ---------- 404 PAGE ---------- */
.error-404-inner {
  text-align: center;
  padding: 3rem 1rem 4rem;
  max-width: 560px;
  margin: 0 auto;
}

.error-404-visual {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.error-404-code {
  font-size: clamp(4rem, 12vw, 7rem);
  font-weight: 900;
  line-height: 1;
  background: linear-gradient(135deg, var(--blue-600), var(--purple-500));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.error-404-symbol {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 900;
  color: var(--blue-600);
  opacity: 0.9;
}

.error-404-title {
  font-size: clamp(1.5rem, 3vw, 1.75rem);
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 0.75rem;
}

.error-404-desc {
  font-size: 1.05rem;
  color: var(--gray-600);
  line-height: 1.6;
  margin-bottom: 2rem;
}

.error-404-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.error-404-links {
  display: flex;
  gap: 1.25rem;
  justify-content: center;
  flex-wrap: wrap;
  font-size: 0.9rem;
}

.error-404-links a {
  color: var(--gray-500);
  font-weight: 500;
}

.error-404-links a:hover {
  color: var(--blue-600);
}

/* Mini Trainer (hero) */
.hero-trainer { position: relative; }

.mini-trainer-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-xl);
  padding: 1.75rem;
  box-shadow: var(--shadow-lg);
}

.mini-trainer-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
}
.mini-trainer-label { font-size: .8rem; color: var(--gray-400); font-weight: 500; }
.mini-trainer-op {
  background: var(--blue-50);
  color: var(--blue-700);
  padding: .2rem .7rem;
  border-radius: 999px;
  font-size: .8rem;
  font-weight: 700;
}

.mini-trainer-problem {
  text-align: center;
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 1.25rem;
  min-height: 3.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.mini-trainer-input {
  display: flex;
  flex-direction: column;
  gap: .5rem;
  margin-bottom: .75rem;
}
.mini-trainer-input .btn-block { width: 100%; }

.mini-input {
  flex: 1;
  padding: .75rem 1rem;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius);
  font-size: 1.2rem;
  font-family: var(--font);
  font-weight: 600;
  text-align: center;
  outline: none;
  transition: border-color var(--transition);
}
.mini-input:focus { border-color: var(--blue-500); }
.mini-input::-webkit-inner-spin-button,
.mini-input::-webkit-outer-spin-button { -webkit-appearance: none; }

.mini-trainer-feedback {
  text-align: center;
  font-weight: 700;
  font-size: .95rem;
  padding: .4rem;
  border-radius: var(--radius-sm);
  margin-bottom: .5rem;
  animation: fadeIn .2s ease;
}
.mini-trainer-feedback.correct { background: var(--green-50); color: var(--green-600); }
.mini-trainer-feedback.wrong   { background: var(--red-50); color: var(--red-500); }

.mini-trainer-stats {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  font-size: .9rem;
  font-weight: 600;
  color: var(--gray-600);
  margin-bottom: .75rem;
}

.mini-trainer-link {
  display: block;
  text-align: center;
  font-size: .85rem;
  color: var(--blue-600);
  font-weight: 600;
  padding-top: .5rem;
  border-top: 1px solid var(--gray-100);
}

/* ---------- BENEFITS ---------- */
.benefits-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

.benefit-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  transition: box-shadow var(--transition), transform var(--transition);
}
.benefit-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.benefit-icon { font-size: 2rem; margin-bottom: 1rem; }
.benefit-card h3 { font-size: 1.1rem; font-weight: 700; margin-bottom: .5rem; color: var(--gray-900); }
.benefit-card p { color: var(--gray-600); font-size: .95rem; line-height: 1.6; }

/* ---------- HOW IT WORKS ---------- */
.steps {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 2.5rem;
}

.step {
  flex: 1;
  min-width: 180px;
  max-width: 220px;
  text-align: center;
}
.step-num {
  width: 48px;
  height: 48px;
  background: var(--blue-600);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .8rem;
  font-weight: 800;
  margin: 0 auto 1rem;
  letter-spacing: .05em;
}
.step h3 { font-size: 1rem; font-weight: 700; margin-bottom: .4rem; color: var(--gray-900); }
.step p { font-size: .9rem; color: var(--gray-600); line-height: 1.55; }

.step-arrow {
  font-size: 1.5rem;
  color: var(--gray-300);
  align-self: center;
  padding-top: .5rem;
  flex-shrink: 0;
}

.steps-cta { text-align: center; }

/* ---------- TRAINER PROMO ---------- */
.trainer-promo-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.trainer-promo-content h2 {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--gray-900);
  margin-bottom: 1rem;
}
.trainer-promo-content p {
  color: var(--gray-600);
  margin-bottom: 1.5rem;
  font-size: 1rem;
  line-height: 1.7;
}

.feature-list { margin-bottom: 1.75rem; }
.feature-list li {
  padding: .4rem 0;
  color: var(--gray-700);
  font-size: .95rem;
}

/* Снимок для static/images/trainer-promo.png: /trenazher/?promo=capture — только колонка с примером */
body.trainer-promo-capture .site-header,
body.trainer-promo-capture .site-footer,
body.trainer-promo-capture .trainer-page-header,
body.trainer-promo-capture .trainer-sidebar-col,
body.trainer-promo-capture .trainer-seo-section,
body.trainer-promo-capture .trainer-settings-details,
body.trainer-promo-capture .trainer-settings-link-wrap {
  display: none !important;
}
body.trainer-promo-capture main {
  padding-top: 0;
  padding-bottom: 0;
}
body.trainer-promo-capture .trainer-wrapper {
  padding-top: 1rem;
  padding-bottom: 1rem;
}
body.trainer-promo-capture .trainer-layout {
  display: block;
  max-width: 640px;
  margin: 0 auto;
}
body.trainer-promo-capture .trainer-main-col {
  max-width: 100%;
}
body.trainer-promo-capture {
  overflow-x: hidden;
}

/* Trainer promo: скриншот страницы тренажёра (static/images/trainer-promo.png) */
.trainer-promo-figure {
  margin: 0;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--gray-200);
  background: var(--gray-100);
}
.trainer-promo-img {
  display: block;
  width: 100%;
  height: auto;
  vertical-align: middle;
}

/* ---------- ARTICLES ---------- */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
}
.articles-grid-full { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }

.article-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  transition: box-shadow var(--transition), transform var(--transition);
  text-decoration: none;
  color: inherit;
}
.article-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.article-category {
  display: inline-block;
  background: var(--blue-50);
  color: var(--blue-700);
  border-radius: 999px;
  padding: .2rem .65rem;
  font-size: .75rem;
  font-weight: 700;
  margin-bottom: .75rem;
  text-transform: uppercase;
  letter-spacing: .03em;
}
.article-card-title { font-size: 1.05rem; font-weight: 700; margin-bottom: .5rem; line-height: 1.4; color: var(--gray-900); }
.article-card-excerpt { color: var(--gray-600); font-size: .9rem; line-height: 1.6; flex: 1; margin-bottom: 1rem; }
.article-card-footer { display: flex; align-items: center; justify-content: space-between; }
.article-read-time { font-size: .8rem; color: var(--gray-400); }
.article-card .article-card-link { font-size: .85rem; font-weight: 600; color: var(--blue-600); }
.article-card:hover .article-card-link { color: var(--blue-800); }

.articles-cta { margin-top: 3rem; text-align: center; }
.articles-cta p { color: var(--gray-500); margin-bottom: 1rem; }
.articles-cta-btns { display: flex; gap: .75rem; justify-content: center; flex-wrap: wrap; }

/* ---------- COURSE CTA (homepage) ---------- */
.course-cta { background: var(--blue-800); color: #fff; }
.course-cta-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}
.course-cta-inner > .course-cta-visual {
  min-width: 0;
}
.course-cta-content h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 800;
  margin-bottom: .5rem;
  color: #fff;
}
.course-cta-lead {
  color: rgba(255,255,255,.92);
  font-size: 1.05rem;
  font-weight: 600;
  line-height: 1.5;
  margin: 0 0 1rem;
}
.course-cta-desc { color: rgba(255,255,255,.8); margin-bottom: 1.5rem; font-size: 1rem; line-height: 1.7; }

.course-features { margin-bottom: 2rem; }
.course-features li {
  display: flex;
  align-items: flex-start;
  gap: .75rem;
  padding: .5rem 0;
  border-bottom: 1px solid rgba(255,255,255,.08);
  font-size: .95rem;
  color: rgba(255,255,255,.9);
}
.course-features li:last-child { border-bottom: none; }
.cf-icon { font-size: 1.1rem; flex-shrink: 0; padding-top: .1rem; }

.course-cta-actions { display: flex; gap: .75rem; flex-wrap: wrap; margin-bottom: 1rem; }
.course-cta-note { font-size: .82rem; color: rgba(255,255,255,.55); }

.course-modules {
  background: rgba(255,255,255,.08);
  border: 1px solid rgba(255,255,255,.12);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  min-width: 0;
}
.course-modules h4 { color: rgba(255,255,255,.7); font-size: .8rem; font-weight: 600; text-transform: uppercase; letter-spacing: .08em; margin-bottom: 1rem; }
.modules-list {
  margin: 0;
  padding-left: 2.5rem;
  list-style-position: outside;
}
.modules-list li {
  padding: .4rem 0;
  border-bottom: 1px solid rgba(255,255,255,.06);
  font-size: .9rem;
  color: rgba(255,255,255,.85);
}
.modules-list li:last-child { border-bottom: none; }
.modules-list li.more { color: rgba(255,255,255,.45); font-style: italic; }

/* ---------- LEAD SECTION ---------- */
.lead-inner {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
  background: #fff;
  border: 2px solid var(--blue-100);
  border-radius: var(--radius-xl);
  padding: 2rem 2.5rem;
}
.lead-icon { font-size: 2.5rem; flex-shrink: 0; }
.lead-content { flex: 1; min-width: 200px; }
.lead-content h2 { font-size: 1.2rem; font-weight: 800; color: var(--gray-900); margin-bottom: .35rem; }
.lead-content p { color: var(--gray-600); font-size: .9rem; }
.lead-form-inline { display: flex; gap: .5rem; flex-wrap: wrap; }
.lead-form-inline .form-input { flex: 1; min-width: 200px; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 720px; margin: 0 auto; }
.faq-item {
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  margin-bottom: .75rem;
  overflow: hidden;
  transition: border-color var(--transition);
}
.faq-item[open] { border-color: var(--blue-300, #93c5fd); }
.faq-question {
  padding: 1rem 1.25rem;
  cursor: pointer;
  font-weight: 600;
  color: var(--gray-800);
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  user-select: none;
}
.faq-question::-webkit-details-marker { display: none; }
.faq-question::after {
  content: '+';
  font-size: 1.2rem;
  font-weight: 400;
  color: var(--gray-400);
  flex-shrink: 0;
  transition: transform var(--transition);
}
.faq-item[open] .faq-question::after { transform: rotate(45deg); }
.faq-answer {
  padding: 0 1.25rem 1rem;
  color: var(--gray-600);
  font-size: .95rem;
  line-height: 1.7;
}

/* ---------- FORMS ---------- */
.form-input {
  padding: .7rem 1rem;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: .95rem;
  color: var(--gray-800);
  background: #fff;
  width: 100%;
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}
.form-input:focus {
  border-color: var(--blue-500);
  box-shadow: 0 0 0 3px rgba(59,130,246,.15);
}
.form-input::placeholder { color: var(--gray-400); }

/* ---------- MODAL ---------- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.55);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity .25s ease;
}
.modal-overlay.open { opacity: 1; pointer-events: all; }

.modal {
  background: #fff;
  border-radius: var(--radius-xl);
  padding: 2.5rem 2rem;
  max-width: 420px;
  width: 100%;
  position: relative;
  box-shadow: var(--shadow-lg);
  transform: translateY(16px);
  transition: transform .25s ease;
}
.modal-overlay.open .modal { transform: translateY(0); }
.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: var(--gray-100);
  border: none;
  border-radius: 50%;
  width: 32px;
  height: 32px;
  cursor: pointer;
  font-size: .9rem;
  color: var(--gray-500);
  display: flex;
  align-items: center;
  justify-content: center;
}
.modal-close:hover { background: var(--gray-200); }
.modal-icon { font-size: 2.5rem; text-align: center; margin-bottom: 1rem; }
.modal h3 { font-size: 1.25rem; font-weight: 800; text-align: center; margin-bottom: .5rem; }
.modal p { text-align: center; color: var(--gray-500); font-size: .9rem; margin-bottom: 1.25rem; }
.lead-form { display: flex; flex-direction: column; gap: .75rem; }
.modal-note { font-size: .78rem; color: var(--gray-400); text-align: center; margin-top: .5rem; }

/* ---------- BREADCRUMB ---------- */
.breadcrumb {
  font-size: .82rem;
  color: var(--gray-400);
  margin-bottom: 1.5rem;
}
.breadcrumb a { color: var(--gray-400); }
.breadcrumb a:hover { color: var(--blue-600); }
.breadcrumb span { color: var(--gray-600); }

/* ---------- CATEGORY FILTER ---------- */
.category-filter {
  display: flex;
  gap: .5rem;
  flex-wrap: wrap;
  margin-bottom: 2rem;
}
.cat-btn {
  padding: .4rem 1rem;
  border-radius: 999px;
  border: 1.5px solid var(--gray-200);
  color: var(--gray-600);
  font-size: .85rem;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
  background: #fff;
}
.cat-btn:hover { border-color: var(--blue-400, #60a5fa); color: var(--blue-600); background: var(--blue-50); }
.cat-btn.active { border-color: var(--blue-600); background: var(--blue-600); color: #fff; }

/* ---------- ARTICLE PAGE ---------- */
.article-layout {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 3rem;
  align-items: start;
  padding: 3rem 0 4rem;
}

.article-header h1 { font-size: clamp(1.5rem, 3.5vw, 2.2rem); font-weight: 900; line-height: 1.25; margin-bottom: 1rem; }
.article-meta {
  display: flex;
  gap: 1rem;
  font-size: .82rem;
  color: var(--gray-400);
  margin-bottom: 1rem;
}
.article-excerpt {
  font-size: 1.1rem;
  color: var(--gray-600);
  line-height: 1.7;
  border-left: 3px solid var(--blue-400, #60a5fa);
  padding-left: 1rem;
  margin-bottom: 2rem;
}

.article-content {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--gray-800);
}
.article-content h2 { font-size: 1.5rem; font-weight: 800; margin: 2.5rem 0 1rem; color: var(--gray-900); }
.article-content h3 { font-size: 1.15rem; font-weight: 700; margin: 2rem 0 .75rem; color: var(--gray-900); }
.article-content p { margin-bottom: 1.25rem; }
.article-content ul, .article-content ol { margin: 1rem 0 1.25rem 1.5rem; }
.article-content li { margin-bottom: .5rem; }
.article-content strong { font-weight: 700; color: var(--gray-900); }
.article-content code {
  background: var(--gray-100);
  border: 1px solid var(--gray-200);
  border-radius: 4px;
  padding: .15rem .4rem;
  font-family: 'Courier New', monospace;
  font-size: .9em;
}
.article-content blockquote {
  border-left: 3px solid var(--blue-400, #60a5fa);
  padding: .5rem 1.25rem;
  margin: 1.5rem 0;
  color: var(--gray-600);
  font-style: italic;
}
.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.5rem 0;
  font-size: .9rem;
}
.article-content th {
  background: var(--gray-100);
  padding: .6rem .9rem;
  text-align: left;
  font-weight: 700;
  border: 1px solid var(--gray-200);
}
.article-content td {
  padding: .55rem .9rem;
  border: 1px solid var(--gray-200);
}
.article-content tr:nth-child(even) td { background: var(--gray-50); }

.article-cta-block {
  display: flex;
  align-items: center;
  gap: 1rem;
  background: var(--blue-50);
  border: 1px solid var(--blue-100);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin: 2.5rem 0;
  flex-wrap: wrap;
}
.article-cta-icon { font-size: 2rem; flex-shrink: 0; }
.article-cta-content { flex: 1; }
.article-cta-content h3 { font-size: 1rem; font-weight: 700; margin-bottom: .25rem; }
.article-cta-content p { font-size: .9rem; color: var(--gray-600); margin: 0; }

.article-course-cta {
  background: var(--blue-800);
  color: #fff;
  border-radius: var(--radius-lg);
  padding: 2rem;
  margin-top: 2.5rem;
}
.article-course-cta h3 { font-size: 1.2rem; font-weight: 800; margin-bottom: .5rem; }
.article-course-cta p { color: rgba(255,255,255,.8); font-size: .9rem; margin-bottom: 1.25rem; }
.article-course-actions { display: flex; gap: .75rem; flex-wrap: wrap; }

/* Sidebar */
.article-sidebar { position: sticky; top: 80px; }
.sidebar-card {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  margin-bottom: 1rem;
}
.sidebar-title { font-size: .95rem; font-weight: 700; color: var(--gray-800); margin-bottom: .75rem; }
.sidebar-empty { font-size: .85rem; color: var(--gray-400); }
.sidebar-cta { background: var(--blue-50); border-color: var(--blue-100); text-align: center; }
.sidebar-cta-icon { font-size: 2rem; margin-bottom: .5rem; }
.sidebar-cta h3 { font-size: 1rem; font-weight: 800; margin-bottom: .35rem; }
.sidebar-cta p { font-size: .85rem; color: var(--gray-600); margin-bottom: .75rem; }
.sidebar-stepik-link { display: block; text-align: center; font-size: .8rem; color: var(--blue-600); margin-top: .5rem; }

.related-list li { border-bottom: 1px solid var(--gray-100); }
.related-list li:last-child { border-bottom: none; }
.related-list a { display: block; padding: .5rem 0; font-size: .9rem; color: var(--gray-700); line-height: 1.4; }
.related-list a:hover { color: var(--blue-600); }

/* ---------- COURSE PAGE ---------- */
.course-hero {
  background: linear-gradient(135deg, var(--blue-800), #0f172a);
  color: #fff;
  padding: 4rem 0;
}
.course-hero-inner {
  display: grid;
  grid-template-columns: 1fr 360px;
  gap: 3rem;
  align-items: start;
}
.course-platform-badge {
  display: inline-block;
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.2);
  border-radius: 999px;
  padding: .3rem .9rem;
  font-size: .82rem;
  font-weight: 600;
  color: rgba(255,255,255,.85);
  margin-bottom: 1rem;
}
.course-hero h1 { font-size: clamp(1.75rem, 4vw, 2.5rem); font-weight: 900; margin-bottom: 1rem; line-height: 1.2; }
.course-hero-desc { color: rgba(255,255,255,.75); font-size: 1.05rem; margin-bottom: 1rem; line-height: 1.7; }
.course-hero-note {
  color: rgba(255,255,255,.62);
  font-size: .95rem;
  line-height: 1.65;
  margin: 0 0 1.5rem;
  max-width: 42em;
}
.course-meta-row { display: flex; flex-wrap: wrap; gap: .75rem; margin-bottom: 1.5rem; }
.course-meta-item {
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.15);
  border-radius: 999px;
  padding: .3rem .85rem;
  font-size: .82rem;
  font-weight: 500;
  color: rgba(255,255,255,.85);
}
.course-price-block { margin-bottom: 1.5rem; }
.course-price { font-size: 2rem; font-weight: 900; }
.course-price-note { font-size: .82rem; color: rgba(255,255,255,.5); margin-top: .25rem; }
.course-hero-actions { display: flex; gap: .75rem; flex-wrap: wrap; }

/* Крошки и вторичная кнопка: контраст на тёмном hero (глобальные .breadcrumb / .btn-ghost — под светлый фон) */
.course-hero .breadcrumb {
  color: rgba(255, 255, 255, 0.55);
}
.course-hero .breadcrumb a {
  color: rgba(255, 255, 255, 0.75);
}
.course-hero .breadcrumb a:hover {
  color: #fff;
}
.course-hero .breadcrumb span {
  color: rgba(255, 255, 255, 0.92);
  font-weight: 600;
}
.course-hero .btn-ghost {
  color: #fff;
  border-color: rgba(255, 255, 255, 0.55);
}
.course-hero .btn-ghost:hover {
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.85);
  color: #fff;
}

.course-hero-trainer-hint {
  margin-top: 1rem;
  font-size: .88rem;
}
.course-hero-trainer-hint a {
  color: rgba(255, 255, 255, 0.78);
  text-decoration: underline;
  text-underline-offset: 0.15em;
}
.course-hero-trainer-hint a:hover {
  color: #fff;
}

.course-trainer-block.section.section-alt {
  border-top: 1px solid var(--gray-100);
  padding-top: 3rem;
  padding-bottom: 3rem;
}
.course-trainer-block-inner {
  max-width: 48rem;
  margin: 0 auto;
}
.course-trainer-panel {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: 1.75rem 2rem;
  box-shadow: var(--shadow-sm);
  border-left: 4px solid var(--blue-500);
}
.course-trainer-heading {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--gray-900);
  margin: 0 0 0.75rem;
  line-height: 1.25;
}
.course-trainer-lead {
  color: var(--gray-600);
  font-size: 1rem;
  line-height: 1.6;
  margin: 0 0 1.25rem;
}
.course-trainer-features {
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
}
.course-trainer-features li {
  position: relative;
  padding-left: 1.5rem;
  margin-bottom: 0.5rem;
  color: var(--gray-700);
  font-size: 0.95rem;
  line-height: 1.55;
}
.course-trainer-features li:last-child {
  margin-bottom: 0;
}
.course-trainer-features li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--green-500);
  font-weight: 700;
}
.course-trainer-cta {
  margin-top: 0.15rem;
}

.course-hero-card {
  background: rgba(255,255,255,.08);
  border: 1px solid rgba(255,255,255,.12);
  border-radius: var(--radius-xl);
  padding: 1.75rem;
  backdrop-filter: blur(4px);
}
.chc-header {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: rgba(255,255,255,.5);
  margin-bottom: 1rem;
}
.chc-list { }
.chc-list li {
  padding: .55rem 0;
  border-bottom: 1px solid rgba(255,255,255,.07);
  font-size: .9rem;
  color: rgba(255,255,255,.85);
  padding-left: 1.25rem;
  position: relative;
}
.chc-list li::before { content: '✓'; position: absolute; left: 0; color: var(--green-500); font-weight: 700; }
.chc-list li:last-child { border-bottom: none; }

.course-about-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; }
.course-about h2 { font-size: 1.5rem; font-weight: 800; margin-bottom: 1rem; }
.course-about p { color: var(--gray-600); margin-bottom: 1rem; line-height: 1.7; }
.author-quote {
  border-left: 3px solid var(--blue-400, #60a5fa);
  padding: .75rem 1rem;
  margin-top: 1.5rem;
  font-style: italic;
  color: var(--gray-600);
  font-size: .95rem;
}
.author-quote cite { display: block; margin-top: .5rem; font-style: normal; font-weight: 600; color: var(--gray-800); }

.course-requirements h3 { font-size: 1rem; font-weight: 700; margin-bottom: .75rem; color: var(--gray-900); }
.req-list li { padding: .35rem 0; font-size: .9rem; color: var(--gray-700); border-bottom: 1px solid var(--gray-100); }
.req-list li:last-child { border-bottom: none; }
.req-list-no li { color: var(--gray-400); }
.course-requirements .req-list { margin-bottom: 1.5rem; }

.modules-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 1rem; }
.module-card {
  display: flex;
  gap: .75rem;
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  align-items: flex-start;
  transition: box-shadow var(--transition);
}
.module-card:hover { box-shadow: var(--shadow-md); }
.module-num {
  width: 32px;
  height: 32px;
  background: var(--blue-50);
  color: var(--blue-700);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .75rem;
  font-weight: 800;
  flex-shrink: 0;
}
.module-info h3 { font-size: .9rem; font-weight: 700; margin-bottom: .2rem; color: var(--gray-900); }
.module-info p { font-size: .8rem; color: var(--gray-500); line-height: 1.4; }

.final-cta {
  background: linear-gradient(135deg, var(--blue-600), var(--blue-800));
  color: #fff;
}
.final-cta-inner { text-align: center; max-width: 640px; margin: 0 auto; }
.final-cta h2 { font-size: 2rem; font-weight: 900; margin-bottom: 1rem; }
.final-cta p { color: rgba(255,255,255,.8); margin-bottom: 2rem; font-size: 1.05rem; }
.final-cta-actions { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; margin-bottom: 1.5rem; }
.final-cta-trust { display: flex; gap: 1.5rem; justify-content: center; flex-wrap: wrap; font-size: .85rem; color: rgba(255,255,255,.6); }

/* ---------- TRAINER PAGE ---------- */
.trainer-wrapper { min-height: 80vh; }
.trainer-page-header { background: var(--gray-900); color: #fff; padding: 2rem 0; }
.trainer-page-title { font-size: 1.75rem; font-weight: 900; margin-bottom: .35rem; }
.trainer-page-desc { color: rgba(255,255,255,.6); font-size: .95rem; }

.trainer-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 2rem;
  padding: 1.25rem 0 2rem;
  align-items: start;
}

.trainer-main-col { min-width: 0; }

/* Op Tabs */
.op-tabs {
  display: flex;
  min-width: 0;
  background: var(--gray-100);
  border-radius: var(--radius-lg);
  padding: .3rem;
  gap: .2rem;
  margin-bottom: 1.25rem;
  overflow-x: auto;
  scrollbar-width: none;
}
.op-tabs::-webkit-scrollbar { display: none; }
.op-tab {
  flex: 1;
  min-width: 80px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: .2rem;
  padding: .6rem .5rem;
  border: none;
  background: transparent;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
  color: var(--gray-500);
  font-family: var(--font);
}
.op-tab:hover { background: #fff; color: var(--gray-800); }
.op-tab.active { background: #fff; color: var(--blue-600); box-shadow: var(--shadow-sm); }
.op-tab:disabled {
  cursor: default;
  opacity: .65;
}
.op-symbol { font-size: 1.2rem; font-weight: 800; }
.op-label { font-size: .72rem; font-weight: 600; }

/* Settings (collapsible, below start CTA) */
.trainer-settings-details {
  margin-top: 1.5rem;
  margin-bottom: 1.5rem;
  min-width: 0;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  background: #fff;
  padding: .75rem 1rem;
}

.trainer-settings-summary {
  cursor: pointer;
  font-size: .9rem;
  font-weight: 700;
  color: var(--gray-700);
  list-style: none;
}

.trainer-settings-summary::-webkit-details-marker { display: none; }

.trainer-settings-summary-text::after {
  content: " ▾";
  color: var(--gray-500);
  font-weight: 500;
}

.trainer-settings-details[open] .trainer-settings-summary-text::after {
  content: " ▴";
}

.trainer-settings-hint-collapse { display: none; }
.trainer-settings-hint-expand::before,
.trainer-settings-hint-collapse::before { content: " — "; color: var(--gray-500); }
.trainer-settings-hint-expand,
.trainer-settings-hint-collapse { color: var(--gray-600); font-size: .85em; font-weight: 500; }
.trainer-settings-details[open] .trainer-settings-hint-expand { display: none; }
.trainer-settings-details[open] .trainer-settings-hint-collapse { display: inline; }

.trainer-settings-details[open] .trainer-settings {
  margin-top: 1rem;
}

.trainer-settings-link-wrap {
  margin-top: -.5rem;
  margin-bottom: 1.5rem;
}
.trainer-settings-link {
  font-size: .9rem;
  color: var(--blue-600);
  font-weight: 600;
  text-decoration: none;
}
.trainer-settings-link:hover { text-decoration: underline; }

/* Settings Row */
.trainer-settings {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}
.setting-group { display: flex; align-items: center; gap: .75rem; flex-wrap: wrap; }
.setting-group--checkbox {
  flex-direction: column;
  align-items: flex-start;
  gap: .2rem;
}
.setting-checkbox-label {
  display: flex;
  align-items: flex-start;
  gap: .5rem;
  cursor: pointer;
  font-size: .88rem;
  font-weight: 600;
  color: var(--gray-800);
  line-height: 1.35;
}
.setting-checkbox-label input[type="checkbox"] {
  margin-top: .15rem;
  flex-shrink: 0;
  width: 1rem;
  height: 1rem;
  accent-color: var(--blue-600);
}
.setting-checkbox-hint {
  margin: 0;
  padding-left: 1.5rem;
  font-size: .76rem;
  color: var(--gray-500);
  line-height: 1.35;
}
.setting-label { font-size: .82rem; font-weight: 600; color: var(--gray-500); white-space: nowrap; }
.btn-group { display: flex; background: var(--gray-100); border-radius: var(--radius); padding: .2rem; gap: .15rem; }
.btn-group--wrap { flex-wrap: wrap; }
.setting-group--sub { margin-top: -.25rem; }
.personal-stat-timed-wrap { display: flex; flex-wrap: wrap; gap: .35rem; }
.personal-stat-timed { font-size: .8rem; white-space: nowrap; }
.seg-btn {
  padding: .4rem .9rem;
  border: none;
  background: transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font);
  font-size: .82rem;
  font-weight: 600;
  cursor: pointer;
  color: var(--gray-600);
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
}
a.seg-btn {
  text-decoration: none;
  display: inline-block;
  box-sizing: border-box;
}
.seg-btn:hover { background: rgba(255,255,255,.6); color: var(--gray-900); }
.seg-btn.active { background: #fff; color: var(--blue-700); box-shadow: var(--shadow-sm); }
.seg-btn:disabled {
  opacity: .6;
  cursor: default;
}

/* Trainer Screens */
.trainer-screen { min-height: 320px; }
.hidden { display: none !important; }

/* Start Screen */
.start-screen {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 300px;
  text-align: center;
  background: var(--gray-50);
  border: 2px dashed var(--gray-200);
  border-radius: var(--radius-xl);
  padding: 3rem 2rem;
  gap: .75rem;
}
.start-icon {
  font-size: 3rem;
  font-weight: 900;
  color: var(--blue-600);
  line-height: 1;
  margin-bottom: .5rem;
}
.start-screen h2 { font-size: 1.4rem; font-weight: 800; color: var(--gray-900); }
.start-screen p { color: var(--gray-500); font-size: .9rem; max-width: 280px; }
.start-hint { font-size: .78rem; color: var(--gray-400); }

/* Stats Bar */
.stats-bar {
  display: flex;
  gap: .5rem;
  margin-bottom: 1rem;
}
.stat-item {
  flex: 1;
  background: var(--gray-50);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: .75rem .5rem;
  text-align: center;
}
.stat-value { font-size: 1.5rem; font-weight: 800; line-height: 1; margin-bottom: .2rem; }
.stat-value.green { color: var(--green-600); }
.stat-value.red   { color: var(--red-500); }
.stat-value.orange { color: var(--orange-500); }
.stat-value.blue  { color: var(--blue-600); }
.stat-label { font-size: .72rem; color: var(--gray-400); font-weight: 500; }

/* Timer Progress */
.timer-progress-wrap {
  height: 4px;
  background: var(--gray-200);
  border-radius: 2px;
  margin-bottom: 1rem;
  overflow: hidden;
}
.timer-progress-bar {
  height: 100%;
  background: var(--blue-600);
  border-radius: 2px;
  width: 100%;
  transition: width .5s linear, background .5s linear;
}

/* Problem Card */
.problem-card {
  background: #fff;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius-xl);
  padding: 2.5rem 2rem;
  text-align: center;
  margin-bottom: 1rem;
  transition: border-color var(--transition);
  min-width: 0;
  overflow: hidden;
}
.problem-card.correct { border-color: var(--green-500); animation: flashGreen .4s ease; }
.problem-card.wrong   { border-color: var(--red-500);   animation: flashRed .4s ease; }

@keyframes flashGreen {
  0%   { background: var(--green-50); }
  100% { background: #fff; }
}
@keyframes flashRed {
  0%   { background: var(--red-50); }
  100% { background: #fff; }
}
@keyframes slideIn {
  from { opacity: 0; transform: translateY(-8px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

.problem-number-hint {
  font-size: .78rem;
  color: var(--gray-400);
  margin-bottom: .5rem;
  min-height: 1rem;
}

.problem-expression {
  font-size: clamp(2rem, 6vw, 3.5rem);
  font-weight: 900;
  color: var(--gray-900);
  margin-bottom: 1.5rem;
  font-variant-numeric: tabular-nums;
  letter-spacing: -.02em;
  animation: slideIn .2s ease;
  max-width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
}

.problem-input-group {
  max-width: 380px;
  margin: 0 auto;
  min-width: 0;
}

.problem-input-row {
  display: flex;
  flex-direction: column;
  gap: .75rem;
  min-width: 0;
}

.answer-input {
  flex: 1;
  min-width: 0;
  padding: .9rem 1rem;
  border: 2px solid var(--gray-200);
  border-radius: var(--radius);
  font-size: 1.3rem;
  font-weight: 700;
  font-family: var(--font);
  text-align: center;
  outline: none;
  color: var(--gray-900);
  transition: border-color var(--transition), box-shadow var(--transition);
  -moz-appearance: textfield;
}
.answer-input:focus {
  border-color: var(--blue-500);
  box-shadow: 0 0 0 3px rgba(59,130,246,.15);
}
.answer-input::-webkit-inner-spin-button,
.answer-input::-webkit-outer-spin-button { -webkit-appearance: none; }

.btn-answer { width: 100%; min-width: auto; }
.btn-answer kbd {
  background: rgba(255,255,255,.2);
  border: 1px solid rgba(255,255,255,.3);
  border-radius: 3px;
  padding: .1rem .3rem;
  font-size: .7rem;
  font-family: var(--font);
}

.numeric-keypad {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: .5rem;
  max-width: 200px;
  margin: 1rem auto 0;
}

.problem-input-group .numeric-keypad {
  margin-left: auto;
  margin-right: auto;
}

.num-key {
  aspect-ratio: 1;
  min-height: 48px;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  background: #fff;
  font-size: 1.1rem;
  font-weight: 700;
  font-family: var(--font);
  color: var(--gray-900);
  cursor: pointer;
  transition: background .15s, border-color .15s;
  -webkit-tap-highlight-color: transparent;
}

.num-key:hover { background: var(--gray-50); border-color: var(--gray-300); }
.num-key:active { background: var(--gray-100); }

@media (min-width: 769px) {
  .numeric-keypad { max-width: 180px; }
  .num-key { min-height: 42px; font-size: 1rem; }
}

.problem-feedback {
  margin-top: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  font-size: 1rem;
  font-weight: 700;
  padding: .5rem 1rem;
  border-radius: var(--radius);
  animation: fadeIn .2s ease;
}
.problem-feedback.correct { background: var(--green-50); color: var(--green-600); }
.problem-feedback.wrong   { background: var(--red-50); color: var(--red-500); }
.feedback-icon { font-size: 1.1rem; }

/* History Strip */
.history-strip {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .5rem 0;
}
.history-label { font-size: .78rem; color: var(--gray-400); white-space: nowrap; }
.history-dots { display: flex; gap: .3rem; flex-wrap: wrap; }

.history-dot {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .65rem;
  font-weight: 700;
}
.history-dot.ok  { background: var(--green-50); color: var(--green-600); border: 1px solid var(--green-500); }
.history-dot.err { background: var(--red-50); color: var(--red-500); border: 1px solid var(--red-400); }

.trainer-controls { margin-top: 1rem; text-align: right; }

/* Results Screen */
.results-screen {
  background: #fff;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-xl);
  padding: 2.5rem 2rem;
  text-align: center;
}
.results-emoji { font-size: 3.5rem; margin-bottom: 1rem; }
.results-title { font-size: 1.75rem; font-weight: 900; margin-bottom: .35rem; }
.results-subtitle { color: var(--gray-500); margin-bottom: 2rem; }
.results-stats { display: flex; justify-content: center; gap: 1.5rem; flex-wrap: wrap; margin-bottom: 2rem; }
.result-stat { text-align: center; }
.result-stat-val { font-size: 2rem; font-weight: 900; color: var(--gray-900); }
.result-stat-lbl { font-size: .8rem; color: var(--gray-400); }
.results-actions { display: flex; gap: .75rem; justify-content: center; flex-wrap: wrap; margin-bottom: 1.5rem; }
.results-actions--wrap { align-items: center; }
.results-catalog-link { text-decoration: none; }
.results-catalog-link:hover { text-decoration: underline; }
.results-cta-hint { font-size: .85rem; color: var(--gray-500); }

/* Trainer Sidebar */
.trainer-sidebar-col { position: sticky; top: 80px; }
.sidebar-difficulty .diff-tips p { font-size: .82rem; color: var(--gray-600); line-height: 1.5; margin-bottom: .5rem; }
.sidebar-difficulty .diff-tips p:last-child { margin-bottom: 0; }

/* Personal Stats */
.personal-stat-item {
  display: flex;
  justify-content: space-between;
  padding: .4rem 0;
  border-bottom: 1px solid var(--gray-100);
  font-size: .85rem;
}
.personal-stat-item:last-child { border-bottom: none; }
.personal-stat-label { color: var(--gray-600); }
.personal-stat-value { font-weight: 700; color: var(--gray-900); }

/* Trainer SEO Section */
.trainer-seo-section { margin-top: 2rem; }
.trainer-seo-inner h2 { font-size: 1.4rem; font-weight: 800; margin-bottom: 1.5rem; color: var(--gray-900); }
.trainer-seo-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 1.5rem; }
.trainer-seo-grid h3 { font-size: 1rem; font-weight: 700; margin-bottom: .4rem; color: var(--gray-900); }
.trainer-seo-grid p { font-size: .9rem; color: var(--gray-600); line-height: 1.6; }

/* ---------- FOOTER ---------- */
.site-footer {
  background: var(--gray-900);
  color: rgba(255,255,255,.7);
  padding: 3rem 0 2rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2.5rem;
}
.footer-logo { margin-bottom: .75rem; }
.footer-logo .logo-text { color: rgba(255,255,255,.5); }
.footer-logo .logo-text strong { color: rgba(255,255,255,.8); }
.footer-logo .logo-icon { background: rgba(255,255,255,.1); }
.footer-tagline { font-size: .82rem; color: rgba(255,255,255,.4); line-height: 1.5; }
.footer-nav h4 { font-size: .75rem; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: rgba(255,255,255,.4); margin-bottom: .75rem; }
.footer-nav ul li { margin-bottom: .4rem; }
.footer-nav-sep {
  height: 0;
  margin: .6rem 0 .4rem;
  padding: 0;
  border-top: 1px solid rgba(255,255,255,.15);
  list-style: none;
}
.footer-nav ul a { font-size: .85rem; color: rgba(255,255,255,.6); transition: color var(--transition); }
.footer-nav ul a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.08);
  padding-top: 1.25rem;
  font-size: .8rem;
  color: rgba(255,255,255,.3);
}
.footer-bottom .footer-contact { margin-top: .65rem; margin-bottom: 0; color: rgba(255,255,255,.42); }
.footer-bottom a { color: rgba(255,255,255,.5); }
.footer-bottom a:hover { color: rgba(255,255,255,.9); }

/* ---------- PAGE CONTENT ---------- */
.page-content { padding: 3rem 0 4rem; }
.page-content h1 { font-size: clamp(1.5rem, 4vw, 2.2rem); font-weight: 900; margin-bottom: .5rem; }
.page-subtitle { color: var(--gray-500); font-size: 1.05rem; margin-bottom: 2rem; }

.empty-state { text-align: center; padding: 3rem; color: var(--gray-400); }
.empty-state p { margin-bottom: 1rem; }

/* ---------- THANKS PAGE ---------- */
.thanks-icon { font-size: 4rem; margin-bottom: 1rem; }

/* ---------- MISC ---------- */
.hidden { display: none !important; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0,0,0,0); }

/* ---------- RESPONSIVE ---------- */
@media (max-width: 1024px) {
  .hero-inner { grid-template-columns: 1fr; gap: 2rem; }
  .hero-trainer { max-width: 440px; margin: 0 auto; }
  .trainer-promo-inner { grid-template-columns: 1fr; }
  .course-cta-inner { grid-template-columns: 1fr; }
  .course-hero-inner { grid-template-columns: 1fr; }
  .article-layout { grid-template-columns: 1fr; }
  .article-sidebar { position: static; }
  .trainer-layout { grid-template-columns: 1fr; }
  .trainer-sidebar-col { position: static; display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .course-about-inner { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .container { padding: 0 1rem; }
  .section { padding: 3rem 0; }
  .course-trainer-block.section.section-alt {
    padding-top: 2.5rem;
    padding-bottom: 2.5rem;
  }
  .course-trainer-panel {
    padding: 1.25rem 1.1rem;
  }
  .hero { padding: 2.5rem 0 2rem; }

  .nav-links {
    display: none;
    position: fixed;
    top: 64px;
    left: 0; right: 0;
    background: #fff;
    border-bottom: 1px solid var(--gray-200);
    flex-direction: column;
    padding: 1rem;
    gap: .25rem;
    box-shadow: var(--shadow-lg);
    z-index: 99;
  }
  .nav-links.open { display: flex; }
  .nav-link { width: 100%; text-align: center; padding: .75rem; }
  .nav-toggle { display: flex; }

  .hero-actions { flex-direction: column; align-items: flex-start; }
  .steps { flex-direction: column; align-items: center; }
  .step-arrow { transform: rotate(90deg); }
  .lead-inner { flex-direction: column; }
  .trainer-settings { flex-direction: column; gap: .75rem; }
  .stats-bar { flex-wrap: wrap; }
  .stat-item { min-width: calc(50% - .25rem); }
  .footer-grid { grid-template-columns: 1fr; }
  .op-tabs { gap: .1rem; padding: .2rem; }
  .op-tab { min-width: 60px; }
}

@media (max-width: 480px) {
  .hero-title { font-size: 1.9rem; }
  .course-hero h1 { font-size: 1.75rem; }
  .modules-grid { grid-template-columns: 1fr; }
  .trainer-sidebar-col { display: flex; flex-direction: column; }
  .results-stats { gap: 1rem; }
}

/* ---------- TRAINER MOBILE-FIRST IMPROVEMENTS ---------- */
.mobile-answer-bar { display: none; }

.trainer-seo-details {
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  background: #fff;
  padding: .9rem 1rem;
}

.trainer-seo-details > summary {
  cursor: pointer;
  font-size: 1.1rem;
  font-weight: 800;
  color: var(--gray-900);
  list-style: none;
}

.trainer-seo-details > summary::-webkit-details-marker { display: none; }

.trainer-seo-details > summary::after {
  content: "▾";
  float: right;
  color: var(--gray-500);
}

.trainer-seo-details[open] > summary::after { content: "▴"; }

details.sidebar-difficulty > summary {
  cursor: pointer;
  list-style: none;
}
details.sidebar-difficulty > summary::-webkit-details-marker { display: none; }

@media (max-width: 900px) {
  .trainer-layout {
    grid-template-columns: 1fr;
    gap: 1rem;
    padding: 1.25rem 0 3.5rem;
  }

  .trainer-sidebar-col {
    position: static;
    display: grid;
    grid-template-columns: 1fr;
  }

  .trainer-page-header {
    padding: 1.2rem 0;
  }

  .trainer-page-title {
    font-size: 1.3rem;
    line-height: 1.2;
  }

  .trainer-page-desc {
    font-size: .9rem;
  }

  .op-tabs {
    margin-bottom: .8rem;
  }

  .op-tab {
    min-width: 62px;
    padding: .5rem .4rem;
  }

  .op-symbol { font-size: 1rem; }
  .op-label { font-size: .66rem; }

  .trainer-settings {
    gap: .65rem;
    margin-bottom: 1rem;
    min-width: 0;
  }

  .setting-group {
    width: 100%;
    display: block;
    min-width: 0;
  }

  .setting-label {
    display: block;
    margin-bottom: .25rem;
  }

  .btn-group:not(.btn-group--wrap) {
    width: 100%;
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
  }
  .btn-group.btn-group--wrap {
    display: flex;
    flex-wrap: wrap;
    width: 100%;
  }

  .seg-btn {
    padding: .5rem .3rem;
    font-size: .74rem;
  }

  .stats-bar {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: .45rem;
  }

  .stat-item {
    min-width: 0;
    padding: .5rem .35rem;
  }

  .stat-value {
    font-size: 1.1rem;
  }

  .problem-card {
    padding: 1rem .8rem;
    border-radius: 14px;
    margin-bottom: .6rem;
  }

  .problem-expression {
    font-size: clamp(1.65rem, 8vw, 2.2rem);
    margin-bottom: .9rem;
  }

  .problem-input-group {
    max-width: none;
  }

  .problem-input-row {
    gap: .45rem;
  }

  .answer-input {
    font-size: 1.05rem;
    padding: .75rem .7rem;
  }

  .numeric-keypad {
    max-width: 220px;
    gap: .55rem;
    margin-top: 1.25rem;
  }

  .num-key {
    min-height: 52px;
    font-size: 1.2rem;
  }

  .btn-answer {
    min-width: 100px;
    padding: .7rem .75rem;
    font-size: .86rem;
  }

  .btn-answer kbd { display: none; }

  .history-strip {
    gap: .45rem;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .history-label {
    position: sticky;
    left: 0;
    background: #fff;
    padding-right: .25rem;
  }

  .trainer-controls {
    display: none;
  }

  .mobile-answer-bar {
    display: block;
    position: sticky;
    bottom: 0;
    z-index: 10;
    padding: .5rem 0 calc(.5rem + env(safe-area-inset-bottom));
    background: linear-gradient(to top, rgba(255,255,255,.97), rgba(255,255,255,.9), rgba(255,255,255,0));
    backdrop-filter: blur(2px);
  }

  .mobile-answer-bar .stop-session-btn {
    width: 100%;
  }

  .mobile-answer-bar .btn {
    border-radius: 12px;
    min-height: 44px;
    font-size: .95rem;
  }

  .trainer-sidebar-col .sidebar-card {
    margin-bottom: .65rem;
  }

  .trainer-seo-section {
    margin-top: .6rem;
  }

  .trainer-seo-details {
    padding: .7rem .75rem;
  }

  .trainer-seo-details > summary {
    font-size: 1rem;
  }

  .trainer-seo-grid {
    grid-template-columns: 1fr;
    gap: .8rem;
    margin-top: .75rem;
  }
}

/* ---------- TRAINER SETTINGS PAGE ---------- */
.settings-page {
  padding: 2rem 0 4rem;
}
.settings-page-header {
  margin-bottom: 2.5rem;
}
.settings-page-header h1 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 900;
  margin-bottom: .5rem;
}
.settings-page-lead {
  color: var(--gray-600);
  font-size: 1.05rem;
  line-height: 1.6;
}
.settings-content {
  max-width: 700px;
}
.settings-section {
  margin-bottom: 2rem;
}
.settings-section h2 {
  font-size: 1.15rem;
  font-weight: 800;
  margin-bottom: .6rem;
  color: var(--gray-900);
}
.settings-section p,
.settings-section ul {
  color: var(--gray-600);
  font-size: .95rem;
  line-height: 1.7;
  margin-bottom: .75rem;
}
.settings-section ul {
  padding-left: 1.5rem;
}
.settings-section li {
  margin-bottom: .35rem;
}
.settings-cta {
  margin-top: 2.5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--gray-200);
}