/* ============================================================
   Математика.СПб.РФ — дизайн-система (образец: информатика.спб.рф; отличие — зелёный основной)
   Светлая и тёмная темы через CSS-переменные ([data-theme]).
   ============================================================ */

/* ---------- Переменные ---------- */
:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "Cascadia Code", Consolas, "SF Mono", Menlo, monospace;

  --radius: 12px;
  --radius-sm: 8px;
  --container: 1140px;
  --container-narrow: 780px;

  --c-bg: #f6f8fb;
  --c-surface: #ffffff;
  --c-surface-2: #eef2f8;
  --c-text: #1a2333;
  --c-text-soft: #55617a;
  --c-border: #dde4ee;

  --c-primary: #059669;
  --c-primary-strong: #047857;
  --c-primary-soft: #d5f3e6;
  --c-accent: #7c3aed;
  --c-accent-soft: #ede9fe;
  --c-ok: #16a34a;
  --c-ok-soft: #dcfce7;
  --c-err: #dc2626;
  --c-err-soft: #fee2e2;
  --c-warn: #d97706;

  --c-code-bg: #0f172a;
  --c-code-text: #e2e8f0;

  --shadow: 0 1px 3px rgba(16, 24, 40, .07), 0 8px 24px rgba(16, 24, 40, .06);
  --shadow-hover: 0 4px 12px rgba(16, 24, 40, .10), 0 12px 32px rgba(16, 24, 40, .10);
}

[data-theme="dark"] {
  --c-bg: #0b1120;
  --c-surface: #131c2e;
  --c-surface-2: #1b2740;
  --c-text: #e6ecf7;
  --c-text-soft: #93a1bd;
  --c-border: #26334d;

  --c-primary: #34d399;
  --c-primary-strong: #6ee7b7;
  --c-primary-soft: #123a2c;
  --c-accent: #a78bfa;
  --c-accent-soft: #2b2350;
  --c-ok: #4ade80;
  --c-ok-soft: #143526;
  --c-err: #f87171;
  --c-err-soft: #3f1d1d;
  --c-warn: #fbbf24;

  --c-code-bg: #0a0f1c;
  --c-code-text: #dbe4f3;

  --shadow: 0 1px 3px rgba(0, 0, 0, .4), 0 8px 24px rgba(0, 0, 0, .35);
  --shadow-hover: 0 4px 12px rgba(0, 0, 0, .5), 0 12px 32px rgba(0, 0, 0, .45);
}

/* ---------- Базовое ---------- */
*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--c-text);
  background: var(--c-bg);
  transition: background .2s, color .2s;
}

img { max-width: 100%; height: auto; }

a { color: var(--c-primary); }
a:hover { color: var(--c-primary-strong); }

h1, h2, h3, h4 { line-height: 1.25; color: var(--c-text); }

.container {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
}

.container--narrow { max-width: var(--container-narrow); }

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  margin: -1px; padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* ---------- Кнопки ---------- */
.btn {
  display: inline-block;
  padding: 11px 22px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: background .15s, transform .1s;
}
.btn:active { transform: translateY(1px); }

.btn-primary { background: var(--c-primary); color: #fff; }
.btn-primary:hover { background: var(--c-primary-strong); color: #fff; }

.btn-secondary {
  background: var(--c-surface);
  color: var(--c-text);
  border: 1px solid var(--c-border);
}
.btn-secondary:hover { border-color: var(--c-primary); color: var(--c-primary); }

/* ---------- Шапка ---------- */
.site-header {
  background: var(--c-surface);
  border-bottom: 1px solid var(--c-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 16px;
  height: 62px;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: 9px;
  text-decoration: none;
  color: var(--c-primary);
  flex-shrink: 0;
}

.logo-text {
  font-size: 19px;
  font-weight: 700;
  color: var(--c-text);
  letter-spacing: -.02em;
}
.logo-tld { color: var(--c-primary); }

.header-search {
  display: flex;
  flex: 1;
  max-width: 380px;
  margin-left: auto;
  background: var(--c-surface-2);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}
.header-search:focus-within { border-color: var(--c-primary); }

.header-search input {
  flex: 1;
  min-width: 0;
  padding: 8px 12px;
  border: none;
  background: transparent;
  color: var(--c-text);
  font-size: 14px;
  outline: none;
}

.header-search button {
  padding: 0 12px;
  border: none;
  background: transparent;
  color: var(--c-text-soft);
  cursor: pointer;
}
.header-search button:hover { color: var(--c-primary); }

/* Переключатель темы */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px; height: 38px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-surface);
  color: var(--c-text-soft);
  cursor: pointer;
  flex-shrink: 0;
}
.theme-toggle:hover { color: var(--c-primary); border-color: var(--c-primary); }

[data-theme="light"] .icon-moon { display: none; }
[data-theme="dark"] .icon-sun { display: none; }

/* Бургер */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 38px; height: 38px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-surface);
  cursor: pointer;
  padding: 8px;
}
.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--c-text);
  border-radius: 2px;
  transition: transform .2s, opacity .2s;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Навигация */
.site-nav { border-top: 1px solid var(--c-border); }

.nav-inner {
  display: flex;
  align-items: center;
  gap: 4px;
  overflow-x: auto;
  padding-top: 6px;
  padding-bottom: 6px;
  scrollbar-width: none;
}
.nav-inner::-webkit-scrollbar { display: none; }

.nav-item {
  padding: 6px 13px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 500;
  color: var(--c-text-soft);
  text-decoration: none;
  white-space: nowrap;
  transition: background .15s, color .15s;
}
.nav-item:hover { background: var(--c-surface-2); color: var(--c-text); }
.nav-item.active { background: var(--c-primary-soft); color: var(--c-primary); }

.nav-item--exam { color: var(--c-accent); font-weight: 600; }
.nav-item--exam:hover { background: var(--c-accent-soft); color: var(--c-accent); }
.nav-item--exam.active { background: var(--c-accent-soft); color: var(--c-accent); }

.nav-item--tools { color: var(--c-warn); font-weight: 600; }

/* ---------- Основной контент ---------- */
.site-main { min-height: 60vh; padding-bottom: 56px; }

/* Герой */
.hero {
  background:
    radial-gradient(900px 380px at 85% -10%, var(--c-primary-soft), transparent),
    radial-gradient(600px 300px at 5% 110%, var(--c-accent-soft), transparent);
  border-bottom: 1px solid var(--c-border);
  padding: 56px 0;
  margin-bottom: 16px;
}

.hero-inner {
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: 40px;
  align-items: center;
}

.hero-kicker {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--c-primary);
  margin: 0 0 10px;
}

.hero-title {
  font-size: clamp(30px, 4.5vw, 44px);
  font-weight: 800;
  letter-spacing: -.02em;
  margin: 0 0 14px;
}

.hero-sub {
  font-size: 17px;
  color: var(--c-text-soft);
  margin: 0 0 24px;
  max-width: 52ch;
}

.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }

.hero-code {
  margin: 0;
  padding: 22px 26px;
  background: var(--c-code-bg);
  color: var(--c-code-text);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-family: var(--font-mono);
  font-size: 15px;
  line-height: 1.7;
  overflow-x: auto;
}
.hc-kw { color: #c084fc; }
.hc-name { color: #7dd3fc; }
.hc-num { color: #fbbf24; }
.hc-str { color: #86efac; }

/* Секции */
.section { padding: 28px 0; }

.section-title {
  font-size: 24px;
  font-weight: 700;
  margin: 0 0 18px;
}

/* Сетки */
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }

.grid-classes {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 14px;
}

/* Карточка класса */
.class-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 20px 10px 16px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  text-align: center;
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.class-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--c-primary);
}

.class-num {
  font-size: 32px;
  font-weight: 800;
  color: var(--c-primary);
  line-height: 1.1;
}
.class-label { font-size: 13px; color: var(--c-text-soft); }
.class-count {
  margin-top: 8px;
  font-size: 12px;
  color: var(--c-text-soft);
  background: var(--c-surface-2);
  border-radius: 999px;
  padding: 2px 9px;
}

/* Карточка экзамена */
.exam-card {
  display: block;
  padding: 24px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.exam-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--c-accent);
  color: var(--c-text);
}
.exam-badge {
  display: inline-block;
  background: var(--c-accent-soft);
  color: var(--c-accent);
  font-size: 13px;
  font-weight: 700;
  border-radius: 999px;
  padding: 3px 12px;
  margin-bottom: 10px;
}
.exam-card h3 { margin: 0 0 8px; font-size: 19px; }
.exam-card p { margin: 0 0 12px; color: var(--c-text-soft); font-size: 15px; }
.exam-more { color: var(--c-accent); font-weight: 600; font-size: 14px; }

/* Карточка инструмента */
.tool-card {
  display: block;
  padding: 24px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.tool-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--c-warn);
  color: var(--c-text);
}
.tool-icon {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  color: var(--c-warn);
  margin-bottom: 8px;
}
.tool-card h3 { margin: 0 0 8px; font-size: 18px; }
.tool-card p { margin: 0; color: var(--c-text-soft); font-size: 15px; }

/* Карточка урока (популярное, поиск) */
.lesson-card {
  display: block;
  padding: 20px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  transition: transform .15s, box-shadow .15s, border-color .15s;
}
.lesson-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--c-primary);
  color: var(--c-text);
}
.lesson-card h3 { margin: 8px 0 6px; font-size: 16px; }
.lesson-card p { margin: 0; color: var(--c-text-soft); font-size: 14px; }

.lesson-card-badge {
  display: inline-block;
  background: var(--c-primary-soft);
  color: var(--c-primary);
  font-size: 12px;
  font-weight: 700;
  border-radius: 999px;
  padding: 2px 10px;
}

/* ---------- Страница раздела ---------- */
.breadcrumbs {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  font-size: 14px;
  color: var(--c-text-soft);
  padding: 18px 0 4px;
}
.breadcrumbs a { color: var(--c-text-soft); text-decoration: none; }
.breadcrumbs a:hover { color: var(--c-primary); }

.page-header { padding: 8px 0 18px; }
.page-header h1 {
  font-size: clamp(26px, 3.5vw, 34px);
  margin: 0 0 8px;
  letter-spacing: -.02em;
}
.page-lead { color: var(--c-text-soft); font-size: 17px; margin: 0 0 6px; max-width: 70ch; }
.page-meta { color: var(--c-text-soft); font-size: 14px; margin: 0; }

.lesson-list {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.lesson-list-item a {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 18px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  transition: border-color .15s, box-shadow .15s;
}
.lesson-list-item a:hover {
  border-color: var(--c-primary);
  box-shadow: var(--shadow);
}

.lesson-num {
  flex-shrink: 0;
  width: 34px; height: 34px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--c-primary-soft);
  color: var(--c-primary);
  border-radius: 50%;
  font-weight: 700;
  font-size: 14px;
}

.lesson-title-wrap { display: flex; flex-direction: column; gap: 2px; min-width: 0; }
.lesson-title { font-weight: 600; }
.lesson-summary { font-size: 13.5px; color: var(--c-text-soft); }

.lesson-arrow { margin-left: auto; color: var(--c-text-soft); flex-shrink: 0; }
.lesson-list-item a:hover .lesson-arrow { color: var(--c-primary); }

/* ---------- Страница урока ---------- */
.lesson-header { padding: 8px 0 6px; }
.lesson-header h1 {
  font-size: clamp(26px, 3.5vw, 34px);
  margin: 0 0 8px;
  letter-spacing: -.02em;
}
.lesson-meta { color: var(--c-text-soft); font-size: 14px; margin: 0 0 10px; }

.lesson-content {
  font-size: 16.5px;
  line-height: 1.75;
}

.lesson-content h2 {
  font-size: 23px;
  margin: 36px 0 12px;
  padding-top: 8px;
}
.lesson-content h3 { font-size: 19px; margin: 28px 0 10px; }
.lesson-content p { margin: 0 0 14px; }
.lesson-content ul, .lesson-content ol { margin: 0 0 14px; padding-left: 26px; }
.lesson-content li { margin-bottom: 6px; }
.lesson-content img {
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow);
  margin: 10px 0;
}
.lesson-content blockquote {
  margin: 16px 0;
  padding: 12px 18px;
  border-left: 4px solid var(--c-primary);
  background: var(--c-surface);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

/* Таблицы контента */
.lesson-content table {
  border-collapse: collapse;
  margin: 16px 0;
  width: 100%;
  background: var(--c-surface);
  border-radius: var(--radius-sm);
  overflow: hidden;
  font-size: 15px;
}
.lesson-content th, .lesson-content td {
  border: 1px solid var(--c-border);
  padding: 8px 12px;
  text-align: left;
}
.lesson-content th { background: var(--c-surface-2); font-weight: 600; }

/* Код в контенте */
.lesson-content code {
  font-family: var(--font-mono);
  font-size: .92em;
  background: var(--c-surface-2);
  border-radius: 5px;
  padding: 2px 6px;
}

.lesson-content pre {
  background: var(--c-code-bg);
  color: var(--c-code-text);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
  overflow-x: auto;
  margin: 16px 0;
  font-size: 14.5px;
  line-height: 1.6;
}
.lesson-content pre code {
  background: none;
  padding: 0;
  font-size: inherit;
  color: inherit;
}

/* Подсветка кода (highlight.js, своя палитра под обе темы) */
.hljs-keyword, .hljs-literal { color: #c084fc; }
.hljs-string { color: #86efac; }
.hljs-number { color: #fbbf24; }
.hljs-comment { color: #64748b; font-style: italic; }
.hljs-title, .hljs-function { color: #7dd3fc; }
.hljs-built_in, .hljs-type { color: #5eead4; }
.hljs-operator, .hljs-punctuation { color: #cbd5e1; }
.hljs-variable, .hljs-params { color: #e2e8f0; }

/* Подсказка про инструмент */
.tool-hint {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 14px 0;
  padding: 13px 16px;
  background: var(--c-surface);
  border: 1px solid var(--c-warn);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  font-size: 15px;
}
.tool-hint:hover { box-shadow: var(--shadow); color: var(--c-text); }
.tool-hint-icon { font-size: 18px; }
.tool-hint-arrow { margin-left: auto; color: var(--c-warn); font-weight: 700; }

/* Навигация между уроками */
.lesson-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 36px 0 8px;
}

.lesson-nav-link {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 14px 16px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  transition: border-color .15s;
}
.lesson-nav-link:hover { border-color: var(--c-primary); }
.lesson-nav-next { text-align: right; }
.lesson-nav-dir { font-size: 13px; color: var(--c-text-soft); }
.lesson-nav-title { font-size: 14.5px; font-weight: 600; color: var(--c-text); }

/* ---------- Тест «Проверь себя» ---------- */
.quiz {
  margin: 40px 0 10px;
  padding: 24px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
}

.quiz-title { margin: 0 0 6px; font-size: 22px; }
.quiz-intro { margin: 0 0 18px; color: var(--c-text-soft); font-size: 15px; }

.quiz-q {
  padding: 16px 0;
  border-top: 1px solid var(--c-border);
}

.quiz-q-title {
  font-weight: 600;
  margin: 0 0 12px;
  display: flex;
  gap: 10px;
}
.quiz-q-num { color: var(--c-primary); flex-shrink: 0; }

.quiz-options { display: flex; flex-direction: column; gap: 8px; }

.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 14px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color .12s, background .12s;
  font-size: 15px;
}
.quiz-option:hover { border-color: var(--c-primary); }
.quiz-option input { margin-top: 3px; accent-color: var(--c-primary); }

.quiz-option.is-correct {
  border-color: var(--c-ok);
  background: var(--c-ok-soft);
}
.quiz-option.is-wrong {
  border-color: var(--c-err);
  background: var(--c-err-soft);
}

.quiz-input {
  width: 100%;
  max-width: 320px;
  padding: 10px 14px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-bg);
  color: var(--c-text);
  font-size: 15px;
}
.quiz-input:focus { outline: none; border-color: var(--c-primary); }
.quiz-input.is-correct { border-color: var(--c-ok); background: var(--c-ok-soft); }
.quiz-input.is-wrong { border-color: var(--c-err); background: var(--c-err-soft); }

.quiz-check {
  margin-top: 12px;
  padding: 8px 18px;
  font-size: 14px;
}

.quiz-feedback {
  margin-top: 10px;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 14.5px;
  display: none;
}
.quiz-feedback.is-ok { display: block; background: var(--c-ok-soft); color: var(--c-ok); }
.quiz-feedback.is-err { display: block; background: var(--c-err-soft); color: var(--c-err); }
.quiz-feedback .quiz-explain { color: var(--c-text-soft); display: block; margin-top: 4px; }

.quiz-summary {
  margin-top: 18px;
  padding: 14px 18px;
  background: var(--c-primary-soft);
  color: var(--c-primary);
  border-radius: var(--radius-sm);
  font-weight: 600;
  display: none;
}
.quiz-summary.visible { display: block; }

/* ---------- Инструменты ---------- */
.tool-panel {
  padding: 24px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  margin-bottom: 26px;
}

.tool-row {
  display: flex;
  gap: 14px;
  align-items: flex-end;
  flex-wrap: wrap;
}

.tool-field {
  display: flex;
  flex-direction: column;
  gap: 5px;
  font-size: 13.5px;
  color: var(--c-text-soft);
  font-weight: 600;
}
.tool-field--grow { flex: 1; min-width: 220px; }

.tool-field input, .tool-field select {
  padding: 10px 13px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-bg);
  color: var(--c-text);
  font-size: 15px;
  font-family: var(--font-mono);
  min-width: 150px;
}
.tool-field input:focus, .tool-field select:focus {
  outline: none;
  border-color: var(--c-primary);
}

.tool-ops { display: flex; gap: 8px; margin-top: 12px; flex-wrap: wrap; }

.tool-op {
  width: 40px; height: 36px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-surface-2);
  color: var(--c-text);
  font-family: var(--font-mono);
  font-size: 16px;
  cursor: pointer;
}
.tool-op:hover { border-color: var(--c-primary); color: var(--c-primary); }

.tool-note { font-size: 13.5px; color: var(--c-text-soft); margin: 10px 0 0; }
.tool-note code {
  font-family: var(--font-mono);
  background: var(--c-surface-2);
  border-radius: 4px;
  padding: 1px 6px;
}

.tool-result { margin-top: 20px; }

.tool-answer {
  font-size: 19px;
  font-weight: 700;
  font-family: var(--font-mono);
  margin: 0 0 12px;
  padding: 12px 16px;
  background: var(--c-ok-soft);
  color: var(--c-ok);
  border-radius: var(--radius-sm);
  overflow-x: auto;
}

.tool-steps summary {
  cursor: pointer;
  font-weight: 600;
  color: var(--c-primary);
  margin-bottom: 8px;
}
.tool-steps div {
  font-family: var(--font-mono);
  font-size: 14.5px;
  line-height: 1.9;
  overflow-x: auto;
}

.tool-error {
  margin-top: 14px;
  padding: 10px 14px;
  background: var(--c-err-soft);
  color: var(--c-err);
  border-radius: var(--radius-sm);
  font-size: 14.5px;
}

.tool-about { margin-top: 8px; }

.table-scroll { overflow-x: auto; }

.truth-table {
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: 14.5px;
  background: var(--c-surface);
}
.truth-table th, .truth-table td {
  border: 1px solid var(--c-border);
  padding: 7px 14px;
  text-align: center;
}
.truth-table th { background: var(--c-surface-2); }
.truth-table td.tt-result { font-weight: 700; color: var(--c-primary); background: var(--c-primary-soft); }

/* ---------- Поиск ---------- */
.search-form {
  display: flex;
  gap: 12px;
  margin: 10px 0 24px;
}
.search-form input {
  flex: 1;
  padding: 12px 16px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-surface);
  color: var(--c-text);
  font-size: 16px;
}
.search-form input:focus { outline: none; border-color: var(--c-primary); }

.search-count { color: var(--c-text-soft); font-size: 14px; }

.search-results {
  list-style: none;
  margin: 0; padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.search-result {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 14px 18px;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--c-text);
  transition: border-color .15s;
}
.search-result:hover { border-color: var(--c-primary); color: var(--c-text); }
.search-result-title { font-weight: 600; }
.search-result-summary { font-size: 14px; color: var(--c-text-soft); }
.search-result .lesson-card-badge { align-self: flex-start; }

.search-empty { color: var(--c-text-soft); }

/* ---------- Реклама ---------- */
.ad-slot { margin: 18px 0; min-height: 0; }

/* ---------- Ошибки ---------- */
.error-page {
  text-align: center;
  padding: 80px 20px;
}
.error-code {
  font-size: 84px;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--c-primary);
  margin: 0;
  line-height: 1;
}
.error-page h1 { margin: 12px 0 8px; }
.error-page p { color: var(--c-text-soft); }

/* ---------- Подвал ---------- */
.site-footer {
  background: var(--c-surface);
  border-top: 1px solid var(--c-border);
  margin-top: 40px;
}

.footer-inner {
  display: grid;
  grid-template-columns: 1.1fr 2fr;
  gap: 40px;
  padding: 36px 20px 28px;
}

.footer-tagline {
  font-size: 14px;
  color: var(--c-text-soft);
  margin: 12px 0;
  max-width: 34ch;
}

.footer-social { display: flex; gap: 14px; }
.footer-social a {
  font-size: 14px;
  color: var(--c-text-soft);
  text-decoration: none;
}
.footer-social a:hover { color: var(--c-primary); }

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.footer-col { display: flex; flex-direction: column; gap: 7px; }
.footer-col h4 {
  margin: 0 0 4px;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--c-text-soft);
}
.footer-col a {
  font-size: 14px;
  color: var(--c-text);
  text-decoration: none;
}
.footer-col a:hover { color: var(--c-primary); }

.footer-bottom {
  border-top: 1px solid var(--c-border);
  padding: 14px 0;
  font-size: 13px;
  color: var(--c-text-soft);
}
.footer-bottom p { margin: 0; }

/* ---------- Адаптив ---------- */
@media (max-width: 960px) {
  .grid-classes { grid-template-columns: repeat(4, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .hero-inner { grid-template-columns: 1fr; }
  .hero-art { display: none; }
}

@media (max-width: 680px) {
  .header-search { display: none; }

  .nav-toggle { display: flex; margin-left: auto; }
  .theme-toggle { margin-left: auto; }
  .header-inner { gap: 10px; }
  .nav-toggle { margin-left: 0; }

  .site-nav { display: none; }
  .site-nav.open { display: block; }
  .nav-inner { flex-wrap: wrap; }

  .grid-2, .grid-3 { grid-template-columns: 1fr; }
  .grid-classes { grid-template-columns: repeat(3, 1fr); }

  .lesson-nav { grid-template-columns: 1fr; }
  .lesson-nav-next { text-align: left; }

  .footer-inner { grid-template-columns: 1fr; gap: 24px; }
  .footer-links { grid-template-columns: 1fr 1fr; }

  .hero { padding: 36px 0; }
}