/*
 * Компоненты поверх токенов design-system.css.
 *
 * Принцип яркости (docs/design-system.md):
 *   навигация и discovery  -> ярко (тёмный navy, lime-акценты)
 *   чтение и понимание     -> чисто (светлый фон, спокойная типографика)
 *   интерактив и тесты     -> выразительно
 *   учительские материалы  -> структурно
 */

/* ============================================================ Header */

.s5-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--s5-navy);
  color: var(--s5-text-on-dark);
}

.s5-header__bar {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  min-height: var(--s5-header-height);
}

.s5-logo {
  display: inline-flex;
  align-items: baseline;
  gap: 0.28em;
  flex-shrink: 0;
  font-size: 1.0625rem;
  font-weight: 900;
  letter-spacing: -0.02em;
  color: var(--s5-text-on-dark);
  text-decoration: none;
  white-space: nowrap;
}

.s5-logo__mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.65em;
  height: 1.65em;
  border-radius: var(--s5-radius-sm);
  background: var(--s5-lime);
  color: var(--s5-text-on-lime);
  font-weight: 900;
  font-size: 0.9em;
  transform: rotate(-4deg);
}

.s5-logo__text small {
  display: block;
  font-size: 0.62em;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--s5-text-on-dark-muted);
}

.s5-header__nav {
  display: none;
  align-items: center;
  gap: var(--s5-space-1);
  margin-left: var(--s5-space-3);
}

.s5-header__nav a {
  padding: var(--s5-space-2) var(--s5-space-3);
  border-radius: var(--s5-radius-pill);
  color: var(--s5-text-on-dark-muted);
  font-size: var(--s5-text-sm);
  font-weight: 600;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--s5-transition), background var(--s5-transition);
}

.s5-header__nav a:hover,
.s5-header__nav a:focus-visible {
  color: var(--s5-text-on-dark);
  background: rgba(255, 255, 255, 0.09);
}

.s5-header__nav a[aria-current='page'] {
  color: var(--s5-lime);
  background: rgba(198, 244, 50, 0.12);
}

.s5-header__search {
  flex: 1;
  min-width: 0;
  max-width: 340px;
  margin-left: auto;
  display: none;
}

.s5-header__actions {
  display: flex;
  align-items: center;
  gap: var(--s5-space-2);
  margin-left: auto;
}

.s5-header__teacher {
  display: none;
  align-items: center;
  gap: var(--s5-space-2);
  padding: var(--s5-space-2) var(--s5-space-4);
  border-radius: var(--s5-radius-pill);
  border: 1px solid rgba(255, 255, 255, 0.22);
  color: var(--s5-text-on-dark);
  font-size: var(--s5-text-sm);
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
  transition: border-color var(--s5-transition), background var(--s5-transition);
}

.s5-header__teacher:hover {
  border-color: var(--s5-lime);
  background: rgba(198, 244, 50, 0.1);
}

.s5-icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  flex-shrink: 0;
  border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: var(--s5-radius-sm);
  background: transparent;
  color: var(--s5-text-on-dark);
  cursor: pointer;
}

.s5-icon-btn:hover {
  border-color: var(--s5-lime);
}

@media (min-width: 900px) {
  .s5-header__nav,
  .s5-header__search,
  .s5-header__teacher {
    display: flex;
  }

  .s5-header__menu-toggle {
    display: none;
  }
}

/* Мобильное меню */

.s5-mobile-menu {
  display: block;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  background: var(--s5-navy);
  overflow: hidden;
}

.s5-mobile-menu[hidden] {
  display: none;
}

.s5-mobile-menu__inner {
  display: grid;
  gap: var(--s5-space-2);
  padding: var(--s5-space-4) 0 var(--s5-space-5);
}

.s5-mobile-menu a {
  padding: var(--s5-space-3) var(--s5-space-4);
  border-radius: var(--s5-radius-md);
  background: rgba(255, 255, 255, 0.06);
  color: var(--s5-text-on-dark);
  font-weight: 700;
  text-decoration: none;
}

.s5-mobile-menu a:hover {
  background: rgba(198, 244, 50, 0.14);
}

@media (min-width: 900px) {
  .s5-mobile-menu {
    display: none !important;
  }
}

/* ============================================================ Search */

.s5-search {
  display: flex;
  align-items: center;
  gap: var(--s5-space-2);
  width: 100%;
  padding: var(--s5-space-2) var(--s5-space-3);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-pill);
  background: var(--s5-surface);
}

.s5-search__icon {
  flex-shrink: 0;
  color: var(--s5-text-faint);
}

.s5-search input[type='search'] {
  flex: 1;
  min-width: 0;
  border: 0;
  background: transparent;
  outline: none;
  font-size: var(--s5-text-sm);
}

.s5-search input[type='search']::placeholder {
  color: var(--s5-text-faint);
}

.s5-search__submit {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  border: 0;
  border-radius: var(--s5-radius-pill);
  background: var(--s5-violet);
  color: #fff;
  cursor: pointer;
  transition: background var(--s5-transition);
}

.s5-search__submit:hover {
  background: var(--s5-violet-dark);
}

/* На тёмном фоне */
.s5-search--on-dark {
  border-color: rgba(255, 255, 255, 0.18);
  background: rgba(255, 255, 255, 0.09);
}

.s5-search--on-dark input[type='search'] {
  color: #fff;
}

.s5-search--on-dark input[type='search']::placeholder {
  color: var(--s5-text-on-dark-muted);
}

.s5-search--on-dark .s5-search__icon {
  color: var(--s5-text-on-dark-muted);
}

/* Крупный поиск на главной */
.s5-search--hero {
  max-width: 620px;
  padding: var(--s5-space-3) var(--s5-space-3) var(--s5-space-3) var(--s5-space-5);
  background: #fff;
  border-color: transparent;
  box-shadow: var(--s5-shadow-lg);
}

.s5-search--hero input[type='search'] {
  font-size: var(--s5-text-lg);
  color: var(--s5-text);
}

.s5-search--hero .s5-search__submit {
  width: 46px;
  height: 46px;
  background: var(--s5-lime);
  color: var(--s5-text-on-lime);
}

.s5-search--hero .s5-search__submit:hover {
  background: var(--s5-lime-dark);
}

/* ============================================================ Buttons */

.s5-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--s5-space-2);
  min-height: 44px;
  padding: var(--s5-space-3) var(--s5-space-5);
  border: 2px solid transparent;
  border-radius: var(--s5-radius-pill);
  font-size: var(--s5-text-sm);
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--s5-transition), background var(--s5-transition),
    border-color var(--s5-transition), box-shadow var(--s5-transition);
}

.s5-btn:hover {
  transform: translateY(-1px);
}

.s5-btn--primary {
  background: var(--s5-violet);
  color: #fff;
}

.s5-btn--primary:hover {
  background: var(--s5-violet-dark);
}

.s5-btn--lime {
  background: var(--s5-lime);
  color: var(--s5-text-on-lime);
  box-shadow: var(--s5-shadow-lime);
}

.s5-btn--lime:hover {
  background: var(--s5-lime-dark);
}

.s5-btn--ghost {
  background: transparent;
  border-color: var(--s5-border-strong);
  color: var(--s5-text);
}

.s5-btn--ghost:hover {
  border-color: var(--subject-color, var(--s5-violet));
  color: var(--subject-color, var(--s5-violet-dark));
}

.s5-btn--on-dark {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.24);
  color: #fff;
}

.s5-btn--on-dark:hover {
  border-color: var(--s5-lime);
  background: rgba(198, 244, 50, 0.14);
}

/* ============================================================ Badges */

.s5-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-1);
  padding: 0.28em 0.8em;
  border-radius: var(--s5-radius-pill);
  background: var(--s5-surface-sunken);
  color: var(--s5-text-muted);
  font-size: var(--s5-text-xs);
  font-weight: 700;
  line-height: 1.4;
  white-space: nowrap;
}

.s5-badge--subject {
  background: var(--subject-color-soft);
  color: var(--subject-color);
}

.s5-badge--lime {
  background: var(--s5-lime);
  color: var(--s5-text-on-lime);
}

.s5-badge--outline-dark {
  background: rgba(255, 255, 255, 0.08);
  color: var(--s5-text-on-dark);
}

.s5-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-2);
  margin-bottom: var(--s5-space-3);
  font-size: var(--s5-text-sm);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--s5-lime);
}

/* ============================================================= Layout */

.s5-section {
  padding: var(--s5-space-7) 0;
}

.s5-section--tight {
  padding: var(--s5-space-6) 0;
}

.s5-section--soft {
  background: var(--s5-surface-soft);
}

.s5-section__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--s5-space-4);
  margin-bottom: var(--s5-space-5);
  flex-wrap: wrap;
}

.s5-section__head h2 {
  margin: 0;
}

.s5-section__link {
  font-size: var(--s5-text-sm);
  font-weight: 700;
  white-space: nowrap;
}

.s5-grid {
  display: grid;
  gap: var(--s5-space-4);
  grid-template-columns: 1fr;
}

@media (min-width: 560px) {
  .s5-grid--2,
  .s5-grid--3,
  .s5-grid--4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .s5-grid--3 {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .s5-grid--4 {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ============================================================== Cards */

.s5-card {
  display: block;
  padding: var(--s5-space-5);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface);
  color: inherit;
  text-decoration: none;
  transition: transform var(--s5-transition), box-shadow var(--s5-transition),
    border-color var(--s5-transition);
}

a.s5-card:hover,
a.s5-card:focus-visible {
  transform: translateY(-3px);
  border-color: var(--subject-color, var(--s5-violet));
  box-shadow: var(--s5-shadow-md);
}

.s5-card__title {
  margin: var(--s5-space-3) 0 var(--s5-space-2);
  font-size: var(--s5-text-lg);
  font-weight: 800;
  line-height: var(--s5-leading-snug);
  letter-spacing: -0.015em;
}

.s5-card__meta {
  margin: 0;
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
  line-height: var(--s5-leading-snug);
}

/* Карточка предмета — крупная, с визуальным символом */

.s5-subject-card {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--s5-space-2);
  min-height: 148px;
  padding: var(--s5-space-5);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface);
  color: inherit;
  text-decoration: none;
  overflow: hidden;
  transition: transform var(--s5-transition), box-shadow var(--s5-transition),
    border-color var(--s5-transition);
}

.s5-subject-card::before {
  content: '';
  position: absolute;
  inset: 0 0 auto 0;
  height: 5px;
  background: var(--subject-color);
}

.s5-subject-card:hover,
.s5-subject-card:focus-visible {
  transform: translateY(-3px);
  border-color: var(--subject-color);
  box-shadow: var(--s5-shadow-md);
}

.s5-subject-card__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--s5-radius-md);
  background: var(--subject-color-soft);
  color: var(--subject-color);
}

.s5-subject-card__icon svg {
  width: 28px;
  height: 28px;
}

.s5-subject-card__name {
  font-size: var(--s5-text-lg);
  font-weight: 800;
  letter-spacing: -0.015em;
}

.s5-subject-card__count {
  margin-top: auto;
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
  font-weight: 600;
}

/* ============================================================== Hero */

.s5-hero {
  position: relative;
  background: var(--s5-navy);
  color: var(--s5-text-on-dark);
  overflow: hidden;
}

/* Мягкое свечение — декоративный слой, не мешает читаемости */
.s5-hero::before {
  content: '';
  position: absolute;
  top: -30%;
  right: -10%;
  width: 60%;
  height: 140%;
  background: radial-gradient(circle at center, rgba(109, 91, 255, 0.35), transparent 62%);
  pointer-events: none;
}

.s5-hero::after {
  content: '';
  position: absolute;
  bottom: -40%;
  left: -12%;
  width: 55%;
  height: 120%;
  background: radial-gradient(circle at center, rgba(198, 244, 50, 0.18), transparent 60%);
  pointer-events: none;
}

.s5-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: var(--s5-space-6);
  padding: var(--s5-space-7) 0 var(--s5-space-8);
  grid-template-columns: 1fr;
  align-items: center;
}

.s5-hero h1 {
  color: #fff;
  margin-bottom: var(--s5-space-4);
  /* Чуть меньше глобального h1: в двухколоночном hero заголовок делит
     ширину с иллюстрацией и на 1440px иначе наезжает на неё. */
  font-size: clamp(1.875rem, 1.4rem + 1.9vw, 2.9rem);
}

.s5-hero h1 em {
  font-style: normal;
  color: var(--s5-lime);
}

.s5-hero__lead {
  max-width: 42ch;
  margin-bottom: var(--s5-space-6);
  color: var(--s5-text-on-dark-muted);
  font-size: var(--s5-text-lg);
}

.s5-hero__actions {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  flex-wrap: wrap;
  margin-top: var(--s5-space-5);
}

.s5-hero__actions-label {
  color: var(--s5-text-on-dark-muted);
  font-size: var(--s5-text-sm);
  font-weight: 600;
}

.s5-hero__art {
  display: none;
}

@media (min-width: 960px) {
  .s5-hero__inner {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: var(--s5-space-7);
  }

  .s5-hero__art {
    display: block;
  }
}

/* Компактный hero для внутренних страниц */

.s5-page-hero {
  position: relative;
  padding: var(--s5-space-6) 0;
  background: var(--s5-navy);
  color: var(--s5-text-on-dark);
  overflow: hidden;
}

.s5-page-hero::after {
  content: '';
  position: absolute;
  top: -60%;
  right: -6%;
  width: 42%;
  height: 200%;
  background: radial-gradient(circle at center, var(--subject-color, var(--s5-violet)), transparent 62%);
  opacity: 0.4;
  pointer-events: none;
}

.s5-page-hero__inner {
  position: relative;
  z-index: 1;
}

.s5-page-hero h1 {
  color: #fff;
  margin-bottom: var(--s5-space-3);
}

.s5-page-hero__lead {
  max-width: 52ch;
  margin-bottom: var(--s5-space-5);
  color: var(--s5-text-on-dark-muted);
}

.s5-page-hero__search {
  max-width: 520px;
}

.s5-page-hero__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  margin-bottom: var(--s5-space-4);
  border-radius: var(--s5-radius-md);
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
}

.s5-page-hero__icon svg {
  width: 32px;
  height: 32px;
}

/* Выбор класса */

.s5-grade-picker {
  display: flex;
  gap: var(--s5-space-3);
  flex-wrap: wrap;
}

.s5-grade-chip {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-2);
  padding: var(--s5-space-3) var(--s5-space-5);
  border: 2px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--s5-radius-pill);
  color: #fff;
  font-size: var(--s5-text-lg);
  font-weight: 800;
  text-decoration: none;
  transition: transform var(--s5-transition), border-color var(--s5-transition),
    background var(--s5-transition);
}

.s5-grade-chip:hover,
.s5-grade-chip:focus-visible {
  transform: translateY(-2px);
  border-color: var(--s5-lime);
  background: rgba(198, 244, 50, 0.14);
}

.s5-grade-picker--light .s5-grade-chip {
  border-color: var(--s5-border-strong);
  color: var(--s5-text);
}

.s5-grade-picker--light .s5-grade-chip:hover {
  border-color: var(--s5-violet);
  background: var(--s5-violet-soft);
}

/* ======================================================= Breadcrumbs */

.s5-breadcrumbs {
  padding: var(--s5-space-4) 0 0;
}

.s5-breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s5-space-2);
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: var(--s5-text-sm);
  color: var(--s5-text-muted);
}

.s5-breadcrumbs li {
  display: flex;
  align-items: center;
  gap: var(--s5-space-2);
}

.s5-breadcrumbs li:not(:last-child)::after {
  content: '';
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--s5-border-strong);
}

.s5-breadcrumbs a {
  color: var(--s5-text-muted);
  text-decoration: none;
}

.s5-breadcrumbs a:hover {
  color: var(--subject-color, var(--s5-violet-dark));
  text-decoration: underline;
}

.s5-breadcrumbs [aria-current='page'] {
  color: var(--s5-text);
  font-weight: 600;
}

/* ========================================================= Topic page */

.s5-topic {
  padding-bottom: var(--s5-space-8);
}

.s5-topic__header {
  padding: var(--s5-space-5) 0 var(--s5-space-6);
}

.s5-topic__kicker {
  display: flex;
  align-items: center;
  gap: var(--s5-space-2);
  flex-wrap: wrap;
  margin-bottom: var(--s5-space-4);
  font-size: var(--s5-text-sm);
  font-weight: 700;
  color: var(--s5-text-muted);
}

.s5-topic__kicker .s5-badge {
  font-size: var(--s5-text-xs);
}

.s5-topic__title {
  display: flex;
  align-items: flex-start;
  gap: var(--s5-space-4);
}

.s5-topic__title h1 {
  margin: 0;
  font-size: clamp(1.7rem, 1.35rem + 1.7vw, 2.6rem);
}

.s5-topic__sign {
  display: none;
  flex-shrink: 0;
  align-items: center;
  justify-content: center;
  width: 68px;
  height: 68px;
  border-radius: var(--s5-radius-lg);
  background: var(--subject-color-soft);
  color: var(--subject-color);
}

.s5-topic__sign svg {
  width: 40px;
  height: 40px;
}

@media (min-width: 720px) {
  .s5-topic__sign {
    display: inline-flex;
  }
}

.s5-topic__mapping {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s5-space-2);
  margin-top: var(--s5-space-4);
}

.s5-topic__mapping-item {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-2);
  padding: var(--s5-space-2) var(--s5-space-3);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-pill);
  background: var(--s5-surface-soft);
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
}

.s5-topic__mapping-item strong {
  color: var(--s5-text);
}

.s5-topic__layout {
  display: grid;
  gap: var(--s5-space-6);
  grid-template-columns: 1fr;
}

@media (min-width: 1000px) {
  .s5-topic__layout {
    grid-template-columns: minmax(0, 1fr) 312px;
    align-items: start;
  }

  .s5-topic__aside {
    position: sticky;
    top: calc(var(--s5-header-height) + var(--s5-space-4));
  }
}

/* Учебные блоки: спокойный ритм, читаемая ширина */

.s5-block {
  padding: var(--s5-space-6) 0;
  border-top: 1px solid var(--s5-border);
}

.s5-block:first-child {
  border-top: 0;
  padding-top: 0;
}

.s5-block h2 {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  margin-bottom: var(--s5-space-4);
}

.s5-block h2 svg {
  width: 22px;
  height: 22px;
  flex-shrink: 0;
  color: var(--subject-color);
}

.s5-block__body {
  max-width: var(--s5-max-reading);
}

/* «Главное за минуту» — ключевой GEO/UX блок */

.s5-answer {
  position: relative;
  padding: var(--s5-space-5) var(--s5-space-5) var(--s5-space-5) var(--s5-space-6);
  border-radius: var(--s5-radius-lg);
  background: var(--subject-color-soft);
  border-left: 5px solid var(--subject-color);
}

.s5-answer__label {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-2);
  margin-bottom: var(--s5-space-2);
  color: var(--subject-color);
  font-size: var(--s5-text-xs);
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.s5-answer__label svg {
  width: 16px;
  height: 16px;
}

.s5-answer p {
  margin: 0;
  font-size: var(--s5-text-lg);
  line-height: var(--s5-leading-snug);
}

/* Ключевые пункты */

.s5-points {
  display: grid;
  gap: var(--s5-space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}

.s5-points li {
  position: relative;
  padding: var(--s5-space-3) var(--s5-space-4) var(--s5-space-3) var(--s5-space-7);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface-soft);
}

.s5-points li::before {
  content: counter(list-item);
  position: absolute;
  left: var(--s5-space-3);
  top: var(--s5-space-3);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--subject-color);
  color: #fff;
  font-size: var(--s5-text-xs);
  font-weight: 800;
}

.s5-points li {
  counter-increment: list-item;
}

/* Определения */

.s5-definitions {
  display: grid;
  gap: var(--s5-space-3);
}

.s5-definition {
  padding: var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface);
}

.s5-definition__term {
  display: block;
  margin-bottom: var(--s5-space-1);
  font-weight: 800;
  color: var(--subject-color);
}

.s5-definition__note {
  margin: var(--s5-space-2) 0 0;
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
}

/* Формула как самостоятельный учебный объект */

.s5-formula {
  margin-bottom: var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface);
  overflow: hidden;
}

.s5-formula__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--s5-space-3);
  padding: var(--s5-space-3) var(--s5-space-4);
  background: var(--s5-surface-soft);
  border-bottom: 1px solid var(--s5-border);
}

.s5-formula__name {
  font-size: var(--s5-text-sm);
  font-weight: 800;
}

/* Место под будущий KaTeX: до его подключения выводим текст,
   но НЕ картинку — формула должна оставаться текстом (ADR-0024). */
.s5-formula__expression {
  padding: var(--s5-space-5) var(--s5-space-4);
  overflow-x: auto;
  font-family: var(--s5-font-mono);
  font-size: 1.3rem;
  text-align: center;
  color: var(--s5-text);
}

.s5-formula__vars {
  display: grid;
  gap: var(--s5-space-2);
  margin: 0;
  padding: var(--s5-space-4);
  border-top: 1px solid var(--s5-border);
  list-style: none;
  font-size: var(--s5-text-sm);
}

.s5-formula__vars li {
  display: flex;
  gap: var(--s5-space-3);
  align-items: baseline;
}

.s5-formula__symbol {
  flex-shrink: 0;
  min-width: 2.6em;
  padding: 0.1em 0.5em;
  border-radius: var(--s5-radius-sm);
  background: var(--subject-color-soft);
  color: var(--subject-color);
  font-family: var(--s5-font-mono);
  font-weight: 700;
  text-align: center;
}

.s5-formula__unit {
  color: var(--s5-text-faint);
}

/* Механизмы и причинные связи */

.s5-mechanism {
  margin-bottom: var(--s5-space-4);
  padding: var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
}

.s5-mechanism__title {
  margin-bottom: var(--s5-space-3);
  font-weight: 800;
}

.s5-mechanism ol {
  margin: 0;
  padding-left: 1.3em;
}

.s5-chain {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  gap: var(--s5-space-2);
  margin-bottom: var(--s5-space-3);
}

.s5-chain__step {
  flex: 1 1 190px;
  padding: var(--s5-space-3) var(--s5-space-4);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface-soft);
  border-left: 3px solid var(--subject-color);
  font-size: var(--s5-text-sm);
}

.s5-chain__arrow {
  display: flex;
  align-items: center;
  color: var(--subject-color);
  font-weight: 800;
}

/* Инфографика */

.s5-figure {
  margin: 0;
}

.s5-figure img {
  width: 100%;
  border-radius: var(--s5-radius-lg);
  border: 1px solid var(--s5-border);
}

.s5-figure figcaption {
  margin-top: var(--s5-space-3);
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
}

/* ============================================================== Video */

.s5-video {
  position: relative;
  border-radius: var(--s5-radius-lg);
  overflow: hidden;
  background: var(--s5-navy-deep);
  aspect-ratio: 16 / 9;
}

.s5-video img,
.s5-video iframe {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border: 0;
}

.s5-video__facade {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: flex-end;
  justify-content: flex-start;
  padding: var(--s5-space-5);
  border: 0;
  background: linear-gradient(to top, rgba(12, 17, 41, 0.85), rgba(12, 17, 41, 0.1) 55%);
  color: #fff;
  cursor: pointer;
  text-align: left;
}

.s5-video__play {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-3);
  font-weight: 700;
}

.s5-video__play-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 52px;
  height: 52px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--s5-lime);
  color: var(--s5-text-on-lime);
  transition: transform var(--s5-transition);
}

.s5-video__facade:hover .s5-video__play-icon {
  transform: scale(1.07);
}

.s5-video__play-icon svg {
  width: 22px;
  height: 22px;
  margin-left: 3px;
}

.s5-video__duration {
  position: absolute;
  top: var(--s5-space-3);
  right: var(--s5-space-3);
  padding: 0.2em 0.6em;
  border-radius: var(--s5-radius-sm);
  background: rgba(12, 17, 41, 0.82);
  color: #fff;
  font-size: var(--s5-text-xs);
  font-weight: 700;
}

/* =========================================================== Self-check */

.s5-quiz {
  display: grid;
  gap: var(--s5-space-4);
}

.s5-quiz__q {
  padding: var(--s5-space-5);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface);
}

.s5-quiz__num {
  display: inline-block;
  margin-bottom: var(--s5-space-2);
  color: var(--s5-text-faint);
  font-size: var(--s5-text-xs);
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.s5-quiz__text {
  margin: 0 0 var(--s5-space-4);
  font-size: var(--s5-text-lg);
  font-weight: 700;
  line-height: var(--s5-leading-snug);
}

.s5-quiz__options {
  display: grid;
  gap: var(--s5-space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}

.s5-quiz__option {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  width: 100%;
  min-height: 48px;
  padding: var(--s5-space-3) var(--s5-space-4);
  border: 2px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface);
  text-align: left;
  cursor: pointer;
  transition: border-color var(--s5-transition), background var(--s5-transition);
}

.s5-quiz__option:hover:not([disabled]) {
  border-color: var(--subject-color);
  background: var(--subject-color-soft);
}

.s5-quiz__marker {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  flex-shrink: 0;
  border: 2px solid var(--s5-border-strong);
  border-radius: 50%;
  font-size: var(--s5-text-xs);
  font-weight: 800;
  color: var(--s5-text-muted);
}

.s5-quiz__marker svg {
  width: 14px;
  height: 14px;
}

/* Состояния ответа: цвет НЕ единственный индикатор — добавлены
   иконка (✓/✕) и подпись, чтобы блок читался при дальтонизме. */
.s5-quiz__option[data-state='correct'] {
  border-color: var(--s5-success);
  background: var(--s5-success-soft);
}

.s5-quiz__option[data-state='correct'] .s5-quiz__marker {
  border-color: var(--s5-success);
  background: var(--s5-success);
  color: #fff;
}

.s5-quiz__option[data-state='incorrect'] {
  border-color: var(--s5-error);
  background: var(--s5-error-soft);
}

.s5-quiz__option[data-state='incorrect'] .s5-quiz__marker {
  border-color: var(--s5-error);
  background: var(--s5-error);
  color: #fff;
}

.s5-quiz__option[disabled] {
  cursor: default;
}

.s5-quiz__verdict {
  display: none;
  align-items: center;
  gap: var(--s5-space-2);
  margin-top: var(--s5-space-4);
  padding: var(--s5-space-3) var(--s5-space-4);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface-soft);
  font-size: var(--s5-text-sm);
}

.s5-quiz__verdict[data-visible='true'] {
  display: flex;
}

.s5-quiz__verdict strong {
  flex-shrink: 0;
}

/* ======================================================= Teacher block */

.s5-teacher-box {
  padding: var(--s5-space-5);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface-soft);
}

.s5-teacher-box__head {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  margin-bottom: var(--s5-space-4);
}

.s5-teacher-box__head h3 {
  margin: 0;
  font-size: var(--s5-text-lg);
}

.s5-teacher-box__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  flex-shrink: 0;
  border-radius: var(--s5-radius-sm);
  background: var(--s5-navy);
  color: var(--s5-lime);
}

.s5-teacher-box__icon svg {
  width: 20px;
  height: 20px;
}

.s5-resources {
  display: grid;
  gap: var(--s5-space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}

.s5-resource {
  display: flex;
  align-items: center;
  gap: var(--s5-space-3);
  min-height: 48px;
  padding: var(--s5-space-3) var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface);
  color: var(--s5-text);
  text-decoration: none;
  transition: border-color var(--s5-transition), transform var(--s5-transition);
}

.s5-resource:hover {
  transform: translateX(2px);
  border-color: var(--s5-violet);
}

.s5-resource__icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  flex-shrink: 0;
  border-radius: var(--s5-radius-sm);
  background: var(--s5-violet-soft);
  color: var(--s5-violet-dark);
}

.s5-resource__icon svg {
  width: 18px;
  height: 18px;
}

.s5-resource__label {
  flex: 1;
  min-width: 0;
  font-size: var(--s5-text-sm);
  font-weight: 600;
  line-height: var(--s5-leading-snug);
}

.s5-resource__size {
  flex-shrink: 0;
  color: var(--s5-text-faint);
  font-size: var(--s5-text-xs);
  font-weight: 600;
}

.s5-provenance {
  margin-top: var(--s5-space-4);
  padding: var(--s5-space-4);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface-soft);
  color: var(--s5-text-muted);
  font-size: var(--s5-text-xs);
  line-height: var(--s5-leading-snug);
}

/* ======================================================== Topic rows */

.s5-topic-rows {
  display: grid;
  gap: var(--s5-space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}

.s5-topic-row {
  display: flex;
  align-items: center;
  gap: var(--s5-space-4);
  padding: var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
  background: var(--s5-surface);
  color: inherit;
  text-decoration: none;
  transition: border-color var(--s5-transition), transform var(--s5-transition),
    box-shadow var(--s5-transition);
}

.s5-topic-row:hover,
.s5-topic-row:focus-visible {
  transform: translateX(3px);
  border-color: var(--subject-color);
  box-shadow: var(--s5-shadow-sm);
}

.s5-topic-row__para {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  padding: var(--s5-space-2);
  flex-shrink: 0;
  border-radius: var(--s5-radius-sm);
  background: var(--subject-color-soft);
  color: var(--subject-color);
  font-size: var(--s5-text-sm);
  font-weight: 800;
}

.s5-topic-row__body {
  flex: 1;
  min-width: 0;
}

.s5-topic-row__title {
  font-weight: 700;
  line-height: var(--s5-leading-snug);
}

.s5-topic-row__excerpt {
  margin: var(--s5-space-1) 0 0;
  color: var(--s5-text-muted);
  font-size: var(--s5-text-sm);
  line-height: var(--s5-leading-snug);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.s5-topic-row__chevron {
  flex-shrink: 0;
  color: var(--s5-text-faint);
}

/* ========================================================== Prev/next */

.s5-nav-pair {
  display: grid;
  gap: var(--s5-space-3);
  grid-template-columns: 1fr;
}

@media (min-width: 640px) {
  .s5-nav-pair {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.s5-nav-pair a {
  display: block;
  padding: var(--s5-space-4);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-md);
  color: var(--s5-text);
  text-decoration: none;
  transition: border-color var(--s5-transition);
}

.s5-nav-pair a:hover {
  border-color: var(--subject-color);
}

.s5-nav-pair small {
  display: block;
  margin-bottom: var(--s5-space-1);
  color: var(--s5-text-faint);
  font-size: var(--s5-text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.s5-nav-pair span {
  font-weight: 700;
  line-height: var(--s5-leading-snug);
}

.s5-nav-pair a:last-child {
  text-align: right;
}

/* ======================================================== Teacher page */

.s5-filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s5-space-2);
}

.s5-filter {
  display: inline-flex;
  align-items: center;
  gap: var(--s5-space-2);
  min-height: 44px;
  padding: var(--s5-space-2) var(--s5-space-4);
  border: 1px solid var(--s5-border-strong);
  border-radius: var(--s5-radius-pill);
  background: var(--s5-surface);
  font-size: var(--s5-text-sm);
  font-weight: 600;
  cursor: pointer;
  transition: border-color var(--s5-transition), background var(--s5-transition),
    color var(--s5-transition);
}

.s5-filter svg {
  width: 16px;
  height: 16px;
}

.s5-filter:hover {
  border-color: var(--s5-violet);
}

.s5-filter[aria-pressed='true'] {
  background: var(--s5-navy);
  border-color: var(--s5-navy);
  color: #fff;
}

.s5-teacher-topic {
  padding: var(--s5-space-5);
  border: 1px solid var(--s5-border);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface);
}

.s5-teacher-topic__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--s5-space-4);
  margin-bottom: var(--s5-space-4);
  flex-wrap: wrap;
}

.s5-teacher-topic__head h3 {
  margin: 0;
}

.s5-empty {
  padding: var(--s5-space-6);
  border: 1px dashed var(--s5-border-strong);
  border-radius: var(--s5-radius-lg);
  background: var(--s5-surface-soft);
  color: var(--s5-text-muted);
  text-align: center;
}

/* ============================================================== Ads */
/* Рекламный слой полностью отделён от контентных компонентов. */

.s5-ad {
  margin: var(--s5-space-6) 0;
  text-align: center;
}

.s5-ad--placeholder {
  min-height: 90px;
  border: 1px dashed var(--s5-border-strong);
  border-radius: var(--s5-radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--s5-text-faint);
  font-size: var(--s5-text-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  opacity: 0.55;
}

.s5-ad--placeholder::before {
  content: attr(data-slot);
}

/* ============================================================ Footer */

.s5-footer {
  margin-top: var(--s5-space-8);
  padding: var(--s5-space-7) 0;
  background: var(--s5-navy);
  color: var(--s5-text-on-dark-muted);
  font-size: var(--s5-text-sm);
}

.s5-footer__grid {
  display: grid;
  gap: var(--s5-space-5);
  grid-template-columns: 1fr;
}

@media (min-width: 720px) {
  .s5-footer__grid {
    grid-template-columns: 1.4fr 1fr 1fr;
  }
}

.s5-footer h4 {
  margin: 0 0 var(--s5-space-3);
  color: #fff;
  font-size: var(--s5-text-sm);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.s5-footer ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--s5-space-2);
}

.s5-footer a {
  color: var(--s5-text-on-dark-muted);
  text-decoration: none;
}

.s5-footer a:hover {
  color: var(--s5-lime);
}

.s5-footer__bottom {
  margin-top: var(--s5-space-6);
  padding-top: var(--s5-space-4);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--s5-text-faint);
  font-size: var(--s5-text-xs);
}

/* ============================================================= Search */

.s5-results-count {
  margin-bottom: var(--s5-space-5);
  color: var(--s5-text-muted);
}

/* ============================================================ Doodles */
/* Небольшие декоративные штрихи в духе референса. Всегда aria-hidden
   и всегда позади контента — не мешают чтению. */

.s5-doodle {
  position: absolute;
  color: var(--s5-lime);
  opacity: 0.5;
  pointer-events: none;
}