* { box-sizing: border-box; margin: 0; padding: 0; }

  :root {
    --bg-deep: #0A0E27;
    --bg-mid: #141A3A;
    --bg-surface: rgba(255, 255, 255, 0.04);
    --bg-surface-hover: rgba(255, 255, 255, 0.08);
    --border: rgba(255, 255, 255, 0.1);
    --border-bright: rgba(255, 255, 255, 0.2);
    --text: #E8F0FF;
    --text-soft: #8A98B8;
    --text-dim: #5A6888;
    --accent: #00D4FF;
    --accent-glow: rgba(0, 212, 255, 0.4);
    --accent-soft: rgba(0, 212, 255, 0.15);
    --grid-color: rgba(0, 212, 255, 0.06);
    /* единая скорость анимации интерфейса */
    --t: 0.45s;
    --ease: cubic-bezier(.2,.8,.2,1);
  }

  html, body {
    background: var(--bg-deep);
    color: var(--text);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Inter", Roboto, sans-serif;
    font-size: 15px;
    -webkit-font-smoothing: antialiased;
    transition: background var(--t) var(--ease);
  }

  /* ===== ФОН ===== */
  #particles {
    position: fixed;
    inset: 0;
    z-index: 0;
    opacity: 0.6;
    pointer-events: none;
  }

  .bg-grid {
    position: fixed;
    inset: 0;
    z-index: 0;
    background-image:
      linear-gradient(var(--grid-color) 1px, transparent 1px),
      linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
    background-size: 50px 50px;
    mask-image: radial-gradient(ellipse at center, black 30%, transparent 80%);
    -webkit-mask-image: radial-gradient(ellipse at center, black 30%, transparent 80%);
    pointer-events: none;
  }

  .bg-glow {
    position: fixed;
    inset: 0;
    z-index: 0;
    background: radial-gradient(circle at 50% 30%, var(--accent-soft) 0%, transparent 50%);
    pointer-events: none;
    transition: background var(--t) var(--ease);
  }

  /* ===== ОСНОВНОЙ КОНТЕНТ ===== */
  .app {
    position: relative;
    z-index: 1;
    opacity: 0;
    transition: opacity 0.8s ease;
  }
  .app.visible {
    opacity: 1;
  }

  .container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 22px 32px 60px;
  }

  /* ===== ВЕРХНЯЯ СТРОКА ===== */
  .topbar {
    display: flex;
    align-items: center;
    gap: 24px;
    margin-bottom: 40px;
	justify-content: space-between;
  }

  .brand {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
    font-size: 18px;
    letter-spacing: 1px;
    color: var(--text);
    white-space: nowrap;
  }
  .brand-logo {
    width: 38px; height: 38px;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--accent), rgba(255,255,255,0.2));
    display: grid;
    place-items: center;
    box-shadow: 0 0 20px var(--accent-glow);
    position: relative;
    overflow: hidden;
    transition: box-shadow var(--t) var(--ease), background var(--t) var(--ease);
  }
  .brand-logo::before {
    content: "";
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent, rgba(255,255,255,0.3));
    animation: shine 3s ease-in-out infinite;
  }
  @keyframes shine {
    0%, 100% { transform: translateX(-100%); }
    50% { transform: translateX(100%); }
  }
  .brand-logo svg {
    position: relative;
    z-index: 1;
    color: var(--bg-deep);
    transition: color var(--t) var(--ease);
  }
  .brand-sub {
    font-size: 10px;
    color: var(--text-soft);
    /*letter-spacing: 2px;*/
    text-transform: uppercase;
    font-weight: 500;
  }

  .subject-switcher {
    display: flex;
    gap: 4px;
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 6px;
    border-radius: 14px;
    border: 1px solid var(--border);
	position: relative;
  }
  /* Плавающая подложка активной кнопки */
  .switcher-pill {
    position: absolute;
    left: 0; top: 0;
    width: 0; height: 0;                 /* размеры задаёт JS */
    border-radius: 10px;
    background: var(--accent);
    box-shadow: 0 0 20px var(--accent-glow);
    z-index: 0;
    pointer-events: none;
    transition: transform var(--t) var(--ease),
                width var(--t) var(--ease),
                height var(--t) var(--ease),
                background var(--t) var(--ease),
                box-shadow var(--t) var(--ease);
  }
  /* при первой отрисовке пилюля должна встать на место без анимации */
  .switcher-pill.no-anim { transition: none; }
  .subject-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
	position: relative;
    z-index: 1;
    border: none;
    background: transparent;
    border-radius: 10px;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-soft);
    cursor: pointer;
    transition: all var(--t) var(--ease);
    white-space: nowrap;
  }
  .subject-btn:hover { color: var(--text); }
  .subject-btn.active {
    color: var(--bg-deep);
  }
  .subject-btn svg {
    width: 16px; height: 16px;
    transition: transform var(--t) var(--ease);
  }
  .subject-btn.active svg {
    animation: iconPulse 2s ease-in-out infinite;
  }
  @keyframes iconPulse {
    0%, 100% { transform: scale(1) rotate(0deg); }
    50% { transform: scale(1.1) rotate(5deg); }
  }

  .search {
    flex: 1;
    max-width: 275px;
    position: relative;
    display: flex;
    align-items: center;
  }
  .search input {
    width: 100%;
    height: 50px;
    padding: 0 44px 0 44px;
    border: 1px solid var(--border);
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: 12px;
    font-size: 13.5px;
    color: var(--text);
    outline: none;
    transition: all var(--t) var(--ease);
  }
  .search input::placeholder { color: var(--text-dim); }
  .search input:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 3px var(--accent-soft), 0 0 20px var(--accent-soft);
  }
  .search svg {
    position: absolute;
    left: 14px; top: 50%;
    transform: translateY(-50%);
    color: var(--text-dim);
    transition: color var(--t) var(--ease);
  }
  .search input:focus + svg { color: var(--accent); }

  /* Кнопка очистки поля */
  .search-clear {
    position: absolute;
    right: 8px; top: 50%;
    transform: translateY(-50%) scale(0.8);
    width: 28px; height: 28px;
    border: none;
    border-radius: 8px;
    background: transparent;
    color: var(--text-dim);
    display: grid;
    place-items: center;
    cursor: pointer;
    opacity: 0;
    pointer-events: none;
    transition: all var(--t) var(--ease);
  }
  .search-clear svg { width: 14px; height: 14px; left: 8px; }
  .search-clear:hover {
    color: var(--accent);
    background: var(--accent-soft);
  }
  .search.filled .search-clear {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(-50%) scale(1);
  }

  /* Бургер-меню */
  .burger {
    display: none;
    width: 38px; height: 38px;
    border-radius: 10px;
    border: 1px solid var(--border);
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    color: var(--text);
    cursor: pointer;
    place-items: center;
    transition: all var(--t) var(--ease);
  }
  .burger:hover { border-color: var(--accent); color: var(--accent); }
  .burger span {
    display: block;
    width: 20px; height: 2px;
    background: currentColor;
    border-radius: 2px;
    transition: all var(--t) var(--ease);
  }
  .burger span + span { margin-top: 5px; }
  .topbar.open .burger span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .topbar.open .burger span:nth-child(2) { opacity: 0; }
  .topbar.open .burger span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

  /* Обёртка «переключатель + поиск» */
  .tools { display: contents; }

  /* ===== СЕКЦИИ ===== */
  .section {
    margin-bottom: 50px;
    animation: sectionFadeIn 0.8s ease both;
  }
  .section:nth-child(2) { animation-delay: 0.1s; }
  .section:nth-child(3) { animation-delay: 0.2s; }
  .section:nth-child(4) { animation-delay: 0.3s; }

  @keyframes sectionFadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .section-header {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 20px;
    padding-bottom: 14px;
    border-bottom: 1px solid var(--border);
  }
  .section-icon {
    width: 36px; height: 36px;
    border-radius: 10px;
    background: var(--accent-soft);
    border: 1px solid var(--accent-soft);
    display: grid;
    place-items: center;
    color: var(--accent);
    transition: all var(--t) var(--ease);
  }
  .section-icon svg {
    width: 18px; height: 18px;
  }
  .section-title {
    font-size: 20px;
    font-weight: 700;
    letter-spacing: -0.3px;
    color: var(--text);
  }
  .section-subtitle {
    font-size: 11px;
    color: var(--text-soft);
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-top: 2px;
  }

  /* ===== ГОРИЗОНТАЛЬНАЯ ПРОКРУТКА ===== */
  .h-scroll {
    display: flex;
    gap: 16px;
    overflow-x: auto;
    overflow-y: hidden;
    scroll-snap-type: x proximity;
    padding: 10px 2px 14px;
    scrollbar-width: thin;
    scrollbar-color: var(--accent-soft) transparent;
    -webkit-overflow-scrolling: touch;
  }
  .h-scroll > * {
    flex: 0 0 calc((100% - (var(--vis) - 0.5) * 16px) / var(--vis));
    scroll-snap-align: start;
  }
  .h-scroll::-webkit-scrollbar { height: 6px; }
  .h-scroll::-webkit-scrollbar-track {
    background: rgba(255,255,255,0.04);
    border-radius: 10px;
  }
  .h-scroll::-webkit-scrollbar-thumb {
    background: var(--accent-soft);
    border: 1px solid var(--border);
    border-radius: 10px;
    transition: background var(--t) var(--ease);
  }
  .h-scroll::-webkit-scrollbar-thumb:hover { background: var(--accent); }

  .no-results {
    flex: 1 1 100%;
    grid-column: 1 / -1;
    text-align: center;
    color: var(--text-dim);
    font-size: 12px;
    font-style: italic;
    padding: 24px 0;
    display: none;
  }
  .no-results.show { display: block; }
  .card-hidden { display: none !important; }

  /* ===== БЛОК КЛАССОВ ===== */
  .classes { --vis: 3.5; }

  .class-col {
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 18px 16px 16px;
    display: flex;
    flex-direction: column;
    gap: 10px;
    transition: all var(--t) var(--ease);
    position: relative;
    overflow: hidden;
  }

  .class-col::before {
    content: "";
    position: absolute;
    top: 0; left: 20%; right: 20%;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent), transparent);
    opacity: 0;
    transition: opacity var(--t) var(--ease), background var(--t) var(--ease);
  }
  .class-col:hover::before { opacity: 1; }

  .class-col:hover {
    background: var(--bg-surface-hover);
    border-color: var(--accent);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3), 0 0 30px var(--accent-soft);
    transform: translateY(-4px);
  }

  .class-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
  }
  .class-num {
    font-size: 28px;
    font-weight: 800;
    letter-spacing: -0.5px;
    color: var(--accent);
    text-shadow: 0 0 20px var(--accent-glow);
    transition: color var(--t) var(--ease), text-shadow var(--t) var(--ease);
  }
  .class-label {
    font-size: 10px;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--text-soft);
    font-weight: 600;
    margin-top: 2px;
  }
  .class-badge {
    font-size: 10px;
    color: var(--accent);
    background: var(--accent-soft);
    padding: 4px 10px;
    border-radius: 20px;
    font-weight: 700;
    letter-spacing: 0.5px;
    border: 1px solid var(--accent-soft);
    transition: all var(--t) var(--ease);
  }

  .topics {
    display: flex;
    flex-direction: column;
    gap: 7px;
    flex: 1;
  }

  .topic {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 9px 11px;
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid transparent;
    border-radius: 10px;
    cursor: pointer;
    text-decoration: none;
    color: var(--text);
    font-size: 12.5px;
    font-weight: 500;
    transition: all var(--t) var(--ease);
  }
  .topic .idx {
    flex-shrink: 0;
    width: 22px; height: 22px;
    border-radius: 6px;
    background: var(--accent-soft);
    color: var(--accent);
    display: grid; place-items: center;
    font-size: 11px;
    font-weight: 700;
    transition: all var(--t) var(--ease);
    border: 1px solid var(--accent-soft);
  }
  .topic .title {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .topic .arrow {
    opacity: 0;
    transform: translateX(-6px);
    transition: all var(--t) var(--ease);
    color: var(--accent);
    font-size: 14px;
  }

  .topic:hover {
    background: var(--accent-soft);
    border-color: var(--accent);
    transform: translateX(4px);
  }
  .topic:hover .idx {
    background: var(--accent);
    color: var(--bg-deep);
    transform: scale(1.1) rotate(-5deg);
    box-shadow: 0 0 12px var(--accent-glow);
  }
  .topic.ready .idx {
    background: var(--accent);
    color: var(--bg-deep);
    border-color: var(--accent);
  }
  .topic:hover .arrow {
    opacity: 1;
    transform: translateX(0);
  }

  .topic.hidden {
    opacity: 0;
    max-height: 0;
    padding-top: 0; padding-bottom: 0;
    margin: 0;
    border-width: 0;
    pointer-events: none;
    transition: all var(--t) var(--ease);
  }
  .topic:not(.hidden) {
    max-height: 60px;
    transition: all var(--t) var(--ease);
  }

  mark {
    transition: background var(--t) var(--ease), box-shadow var(--t) var(--ease);
  }
  .topic mark, .test-card mark, .news-card mark {
    background: var(--accent);
    color: var(--bg-deep);
    padding: 0 3px;
    border-radius: 3px;
    font-weight: 700;
    box-shadow: 0 0 8px var(--accent-glow);
  }

  .class-col.empty .topics::after {
    content: "Нет совпадений";
    display: block;
    text-align: center;
    color: var(--text-dim);
    font-size: 11px;
    padding: 20px 0;
    font-style: italic;
  }

  /* ===== БЛОК ТЕСТОВ ===== */
  .tests-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 16px;
  }

  .test-card {
    display: block;
    text-decoration: none;
    color: inherit;
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 18px;
    transition: all var(--t) var(--ease);
    cursor: pointer;
    position: relative;
    overflow: hidden;
  }

  .test-card::before {
    content: "";
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), transparent);
    opacity: 0.5;
    transition: opacity var(--t) var(--ease), background var(--t) var(--ease);
  }

  .test-card:hover {
    background: var(--bg-surface-hover);
    border-color: var(--accent);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3), 0 0 30px var(--accent-soft);
    transform: translateY(-4px);
  }
  .test-card:hover::before { opacity: 1; }

  .test-class {
    font-size: 12px;
    color: var(--accent);
    font-weight: 700;
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 10px;
    transition: color var(--t) var(--ease);
  }

  .test-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text);
    margin-bottom: 8px;
    line-height: 1.3;
  }

  .test-meta {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 11px;
    color: var(--text-soft);
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border);
  }

  .test-meta-item {
    display: flex;
    align-items: center;
    gap: 4px;
  }

  .test-meta-item svg {
    width: 12px; height: 12px;
    color: var(--accent);
    transition: color var(--t) var(--ease);
  }

  /* ===== БЛОК НОВОСТЕЙ ===== */
  .news-grid { --vis: 4.5; }
  /* ===== БЛОК ОЛИМПИАД ===== */
  .olymp-grid { --vis: 5.5; }

  .news-card {
    display: block;
    text-decoration: none;
    color: inherit;
    background: var(--bg-surface);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border);
    border-radius: 14px;
    overflow: hidden;
    transition: all var(--t) var(--ease);
    cursor: pointer;
  }

  .news-card:hover {
    background: var(--bg-surface-hover);
    border-color: var(--accent);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3), 0 0 30px var(--accent-soft);
    transform: translateY(-4px);
  }

  .news-image {
    width: 100%;
    height: 140px;
    background: linear-gradient(135deg, var(--accent-soft), var(--bg-mid));
    display: grid;
    place-items: center;
    color: var(--accent);
    transition: all var(--t) var(--ease);
    overflow: hidden; 
  }
  .news-image svg {
    width: 40px; height: 40px;
    opacity: 0.5;
  }
  .news-image img {
    object-fit: cover;
    display: block;
    width: 100%;
    height: 100%;
  }

  .news-content {
    padding: 16px;
  }

  .news-date {
    font-size: 10px;
    color: var(--text-dim);
    letter-spacing: 1px;
    text-transform: uppercase;
    margin-bottom: 8px;
  }

  .news-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--text);
    line-height: 1.4;
    margin-bottom: 8px;
  }

  .news-excerpt {
    font-size: 12px;
    color: var(--text-soft);
    line-height: 1.5;
  }

  /* ===== АДАПТИВ ===== */
  @media (max-width: 1200px) {
    .tests-grid { grid-template-columns: repeat(3, 1fr); }
    .classes, .news-grid, .olymp-grid { --vis: 2.5; }
  }
  /* Поиск переносится на отдельную строку */
  @media (max-width: 1000px) {
    .topbar { flex-wrap: wrap; }
    .search {
      order: 3;
      flex: 1 1 100%;
      max-width: none;
    }
  }

  /* Бургер-меню */
  @media (max-width: 786px) {
    .topbar { position: relative; }
    .burger { display: grid; align-content: center; }
    .tools {
      display: none;
      position: absolute;
      top: calc(100% + 12px);
      left: 0; right: 0;
      z-index: 60;
      flex-direction: column;
      gap: 12px;
      padding: 14px;
      background: var(--bg-mid);
      border: 1px solid var(--border);
      border-radius: 16px;
      box-shadow: 0 20px 50px rgba(0,0,0,0.5);
    }
    .topbar.open .tools { display: flex; }
    .subject-switcher {
      width: 100%;
      flex-wrap: wrap;
      justify-content: center;
    }
    .subject-btn { flex: 1 1 auto; justify-content: center; }
    .search {
      order: 0;
      flex: 1 1 auto;
      width: 100%;
      max-width: none;
    }
  }

  @media (max-width: 700px) {
    .tests-grid { grid-template-columns: repeat(2, 1fr); }
    .classes, .news-grid, .olymp-grid { --vis: 1.1; }
    .container { padding: 16px; }
  }
  @media (max-width: 430px) {
	.brand { font-size: 16px; }
	.brand-sub { font-size: 8px; }
	.subject-btn { padding: 10px 12px; }
  }
  @media (max-width: 390px) {
	.brand { font-size: 14px; }
	.brand-sub { font-size: 6.5px; }
	.subject-btn { padding: 10px 6px; }
  }