/* ================= Базовые переменные и сброс ================= */
:root {
  --bg: #0b0e14;
  --bg-soft: #111624;
  --card: #151b2b;
  --card-2: #1a2134;
  --line: #26304a;
  --text: #e8edf7;
  --muted: #9aa6c0;
  --accent: #facc15;
  --accent-2: #22c55e;
  --danger: #ef4444;
  --blue: #3b82f6;
  --orange: #fb923c;
  --radius: 16px;
  --shadow: 0 18px 40px rgba(0, 0, 0, .45);
  --maxw: 1500px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 20px; }

body {
  margin: 0;
  background:
    radial-gradient(1100px 600px at 82% -10%, rgba(250, 204, 21, .10), transparent 60%),
    radial-gradient(900px 500px at 5% 0%, rgba(34, 197, 94, .09), transparent 55%),
    var(--bg);
  color: var(--text);
  font: 16px/1.65 "Segoe UI", Inter, system-ui, -apple-system, Roboto, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 { line-height: 1.22; margin: 0 0 .5em; font-weight: 750; letter-spacing: -.01em; }
h1 { font-size: clamp(30px, 4.6vw, 52px); }
h2 { font-size: clamp(23px, 2.9vw, 34px); }
h3 { font-size: clamp(18px, 2vw, 22px); }
h4 { font-size: 16px; }
p  { margin: 0 0 1em; }
a  { color: var(--accent); }
ul, ol { margin: 0 0 1em; padding-left: 1.25em; }
li { margin: .35em 0; }
strong { color: #fff; }

/* ================= Шапка ================= */
.topbar {
  position: sticky; top: 0; z-index: 60;
  backdrop-filter: blur(14px);
  background: rgba(11, 14, 20, .82);
  border-bottom: 1px solid var(--line);
}
.topbar__in {
  max-width: var(--maxw); margin: 0 auto; padding: 10px 20px;
  display: flex; align-items: center; gap: 14px;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 800; letter-spacing: -.02em; }
.brand__logo {
  width: 30px; height: 30px; border-radius: 8px; display: grid;
  grid-template-columns: repeat(3, 1fr); grid-template-rows: repeat(3, 1fr);
  gap: 2px; padding: 3px; background: #0d1120; border: 1px solid var(--line);
}
.brand__logo i { border-radius: 2px; display: block; }
.topbar__spacer { flex: 1; }
.topbar__hint { color: var(--muted); font-size: 13px; }
@media (max-width: 900px) { .topbar__hint { display: none; } }

/* ================= Раскладка ================= */
.layout {
  max-width: var(--maxw); margin: 0 auto; padding: 22px 20px 80px;
  display: grid; grid-template-columns: 230px minmax(0, 1fr) 380px; gap: 26px;
  align-items: start;
}
@media (max-width: 1280px) { .layout { grid-template-columns: minmax(0,1fr) 350px; } .sidenav { display: none; } }
@media (max-width: 980px)  { .layout { grid-template-columns: minmax(0,1fr); gap: 18px; } }

/* --- левое меню --- */
.sidenav { position: sticky; top: 74px; }
.sidenav ol { list-style: none; margin: 0; padding: 0; }
.sidenav a {
  display: flex; gap: 10px; align-items: center;
  padding: 8px 12px; border-radius: 10px; color: var(--muted);
  text-decoration: none; font-size: 14.5px; border: 1px solid transparent;
}
.sidenav a:hover { color: var(--text); background: var(--card); }
.sidenav a.active { color: #0b0e14; background: var(--accent); font-weight: 700; border-color: var(--accent); }
.sidenav .num {
  width: 22px; height: 22px; flex: none; display: grid; place-items: center;
  border-radius: 6px; background: #1d2437; font-size: 12px; font-weight: 700; color: var(--muted);
}
.sidenav a.active .num { background: rgba(0,0,0,.18); color: #0b0e14; }
.sidenav .sep { margin: 12px 0 6px; padding-left: 12px; font-size: 11px;
  letter-spacing: .14em; text-transform: uppercase; color: #5f6c8c; }

/* ================= Панель с кубиком ================= */
.cubepanel { position: sticky; top: 74px; }
.cubepanel__box {
  background: linear-gradient(180deg, var(--card), #10151f);
  border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); overflow: hidden;
}
.cubepanel__head {
  display: flex; align-items: center; gap: 8px; width: 100%;
  padding: 10px 14px; border: 0; border-bottom: 1px solid var(--line);
  background: transparent; font: inherit; font-size: 13px; color: var(--muted);
  text-align: left; cursor: default;
}
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--accent-2); flex: none; }
.cubepanel__title { flex: none; }
.cubepanel__peek, .cubepanel__chev, .grabber { display: none; }

.cube-stage { display: block; }
.cube-scene {
  height: 320px; display: grid; place-items: center;
  perspective: 1700px; cursor: grab; touch-action: none; user-select: none;
  background:
    radial-gradient(420px 220px at 50% 115%, rgba(250,204,21,.08), transparent 70%);
}
.cube-scene.grabbing { cursor: grabbing; }
.cube-world { position: relative; width: 0; height: 0; transform-style: preserve-3d; }
.cubie { position: absolute; transform-style: preserve-3d; will-change: transform; }

/* Наклейки: чёткая заливка + тонкий тёмный кант. Никаких размытых внутренних
   свечений — именно они делали картинку «мыльной». */
.sticker {
  position: absolute; inset: 0;
  border-radius: 9px;
  border: 3px solid #0a0d14;
  box-shadow: none;
}
.sticker.painted { border-color: rgba(4, 6, 10, .92); }
/* лёгкое затемнение боковых граней — объём без размытия */
.sticker.painted[data-face="R"],
.sticker.painted[data-face="L"] { filter: brightness(.88); }
.sticker.painted[data-face="F"],
.sticker.painted[data-face="B"] { filter: brightness(.95); }
.sticker.painted[data-face="D"] { filter: brightness(.82); }

.cubepanel__moves {
  padding: 10px 12px; border-top: 1px solid var(--line);
  min-height: 46px; display: flex; flex-wrap: wrap; gap: 6px; align-items: center;
}
.mv {
  font: 600 13px/1 ui-monospace, "Cascadia Code", Consolas, monospace;
  padding: 6px 8px; border-radius: 7px; background: #1d2437; color: var(--muted);
  border: 1px solid transparent;
}
.mv.done { color: var(--text); }
.mv.now { background: var(--accent); color: #0b0e14; border-color: #fde68a; transform: translateY(-1px); }
.cubepanel__label { font-size: 12.5px; color: var(--muted); padding: 0 14px 10px; }

.pad { padding: 12px; display: grid; gap: 10px; border-top: 1px solid var(--line); }
.pad__row { display: flex; flex-wrap: wrap; gap: 6px; }
.keycap {
  font: 700 13px/1 ui-monospace, Consolas, monospace;
  padding: 9px 11px; border-radius: 9px; cursor: pointer;
  background: #1d2437; color: var(--text); border: 1px solid var(--line);
}
.keycap:hover { background: #26304a; }
.keycap:active { transform: translateY(1px); }
.keycap.ghost { background: transparent; color: var(--muted); }
.keycap.wide { flex: 1; text-align: center; }

.slider { display: flex; align-items: center; gap: 10px; font-size: 12.5px; color: var(--muted); }
.slider input { flex: 1; accent-color: var(--accent); }

/* ================= БОКОВОЕ МЕНЮ-ШТОРКА (планшет и телефон) ================= */
.nav-toggle { display: none; }
.nav-backdrop { display: none; }
.sidenav__head { display: none; }

@media (max-width: 1280px) {
  .nav-toggle {
    display: inline-flex; flex-direction: column; justify-content: center; gap: 4px;
    width: 40px; height: 40px; padding: 0 9px; flex: none;
    background: #1b2233; border: 1px solid var(--line); border-radius: 10px; cursor: pointer;
  }
  .nav-toggle span { display: block; height: 2px; border-radius: 2px; background: var(--text); }

  .nav-backdrop {
    display: block; position: fixed; inset: 0; z-index: 90;
    background: rgba(4, 6, 10, .65); opacity: 0; pointer-events: none;
    transition: opacity .25s ease;
  }
  body.nav-open .nav-backdrop { opacity: 1; pointer-events: auto; }
  body.nav-open { overflow: hidden; }

  .sidenav {
    display: block; position: fixed; top: 0; left: 0; bottom: 0;
    width: 86%; max-width: 330px; z-index: 95;
    background: var(--bg-soft); border-right: 1px solid var(--line);
    padding: 12px 12px 40px; overflow-y: auto; overscroll-behavior: contain;
    transform: translateX(-102%); transition: transform .28s cubic-bezier(.22,.9,.3,1);
  }
  body.nav-open .sidenav { transform: none; box-shadow: 0 0 50px rgba(0,0,0,.7); }

  .sidenav__head {
    display: flex; align-items: center; justify-content: space-between;
    padding: 6px 8px 12px; margin-bottom: 6px; border-bottom: 1px solid var(--line);
    font-weight: 700; color: var(--text);
  }
  .sidenav__close {
    width: 36px; height: 36px; border-radius: 9px; cursor: pointer;
    background: #1d2437; border: 1px solid var(--line); color: var(--text); font-size: 15px;
  }
  .sidenav a { padding: 11px 12px; font-size: 15px; }
}

/* ================= КУБИК КАК ШТОРКА СНИЗУ (телефон) ================= */
@media (max-width: 980px) {
  .cubepanel {
    position: fixed; left: 0; right: 0; bottom: 0; top: auto; z-index: 80;
    transform: translateY(calc(100% - var(--sheet-peek, 56px)));
    transition: transform .3s cubic-bezier(.22, .9, .3, 1);
    will-change: transform;
  }
  .cubepanel.open { transform: none; }

  .cubepanel__box {
    border-radius: 18px 18px 0 0; border-bottom: 0;
    max-height: 86vh; display: flex; flex-direction: column;
    box-shadow: 0 -14px 40px rgba(0, 0, 0, .65);
  }

  .cubepanel__head {
    position: relative; height: var(--sheet-peek, 56px); flex: none;
    padding: 14px 14px 10px; cursor: pointer; font-size: 13.5px;
  }
  .grabber {
    display: block; position: absolute; top: 6px; left: 50%; transform: translateX(-50%);
    width: 40px; height: 4px; border-radius: 99px; background: #39435f;
  }
  .cubepanel__peek {
    display: block; flex: 1; min-width: 0; color: var(--muted); font-size: 12.5px;
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
  }
  .cubepanel__chev {
    display: block; flex: none; color: var(--muted); font-size: 12px;
    transition: transform .3s ease;
  }
  .cubepanel.open .cubepanel__chev { transform: rotate(180deg); }

  .cubepanel__body { overflow-y: auto; overscroll-behavior: contain; }

  .cube-scene { height: 34vh; min-height: 200px; max-height: 300px; }
  .cubepanel__moves { padding: 8px 12px; flex-wrap: nowrap; overflow-x: auto; }
  /* подпись уже видна в шапке шторки — второй раз не повторяем */
  .cubepanel__label { display: none; }
  .keycap { padding: 12px 13px; font-size: 14px; }
  .pad { padding: 10px 12px 18px; gap: 8px; }
  /* «Ещё раз / Перемешать / Собрать» — самые нужные кнопки, поднимаем их наверх */
  .pad > .pad__row:last-child { order: -1; }
  .slider { order: 1; }
  .keycap.wide { white-space: nowrap; font-size: 13px; padding: 13px 6px; }

  /* чтобы свёрнутая шторка не закрывала конец страницы */
  footer.site { padding-bottom: 90px; }
}

/* ================= Контент ================= */
.hero {
  background: linear-gradient(135deg, rgba(250,204,21,.12), rgba(34,197,94,.08) 45%, transparent 75%), var(--card);
  border: 1px solid var(--line); border-radius: 22px; padding: 30px; margin-bottom: 26px;
}
.hero p.lead { font-size: 18px; color: #c6d0e5; max-width: 62ch; }
.badges { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.badge {
  font-size: 13px; padding: 6px 11px; border-radius: 999px;
  background: #1b2233; border: 1px solid var(--line); color: var(--muted);
}
.badge b { color: var(--accent); }

section.step, section.block {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px; margin-bottom: 22px; scroll-margin-top: 80px;
}
section.step { border-left: 3px solid var(--accent); }

.step__top { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 6px; }
.step__num {
  width: 34px; height: 34px; border-radius: 10px; display: grid; place-items: center;
  background: var(--accent); color: #0b0e14; font-weight: 800; flex: none;
}
.step__goal {
  display: flex; gap: 12px; padding: 14px 16px; border-radius: 12px;
  background: rgba(34,197,94,.08); border: 1px solid rgba(34,197,94,.28); margin: 14px 0 18px;
}
.step__goal b { color: var(--accent-2); }

.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 760px) { .grid2 { grid-template-columns: 1fr; } }

.note, .warn, .tip {
  border-radius: 12px; padding: 13px 16px; margin: 14px 0; font-size: 15px;
  border: 1px solid var(--line); background: var(--card-2);
}
.note  { border-left: 3px solid var(--blue); }
.warn  { border-left: 3px solid var(--danger); background: rgba(239,68,68,.07); }
.tip   { border-left: 3px solid var(--accent-2); background: rgba(34,197,94,.06); }
/* блочным делаем только заголовок подсказки — первый <b>;
   буквы ходов внутри текста должны оставаться строчными */
.note > b:first-child,
.warn > b:first-child,
.tip  > b:first-child { display: block; margin-bottom: 3px; }

/* --- карточка ситуации --- */
.case {
  background: var(--card-2); border: 1px solid var(--line); border-radius: 14px;
  padding: 16px; display: flex; flex-direction: column; gap: 10px;
}
.case__title { display: flex; align-items: center; gap: 9px; font-weight: 700; font-size: 16px; }
.case__tag {
  font-size: 11px; letter-spacing: .08em; text-transform: uppercase; color: #0b0e14;
  background: var(--accent); padding: 3px 7px; border-radius: 5px; font-weight: 800;
}
.case p { margin: 0; font-size: 14.6px; color: #c3cde2; }
.case .look { font-size: 14px; color: var(--muted); }
.case .look b { color: var(--accent); }
.case__foot { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; margin-top: auto; }

.alg {
  font: 700 15px/1.4 ui-monospace, "Cascadia Code", Consolas, monospace;
  background: #0d1120; border: 1px solid var(--line); color: var(--accent);
  padding: 9px 12px; border-radius: 10px; display: inline-block; letter-spacing: .04em;
}
.alg.small { font-size: 13.5px; padding: 7px 10px; }

button.demo {
  border: 0; cursor: pointer; font-weight: 700; font-size: 14px;
  padding: 10px 15px; border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), #f59e0b); color: #0b0e14;
  display: inline-flex; align-items: center; gap: 7px;
}
button.demo:hover { filter: brightness(1.08); }
button.demo:active { transform: translateY(1px); }
button.demo.secondary { background: #253052; color: var(--text); }

/* --- схемы --- */
.diagram { display: inline-block; }
.diagram svg { display: block; }
.diagrams { display: flex; flex-wrap: wrap; gap: 18px; align-items: flex-start; margin: 8px 0; }
.dgm-item { text-align: center; font-size: 13px; color: var(--muted); }
.dgm-item .cap { margin-top: 6px; display: block; }

/* --- переключатель обозначений --- */
.switcher {
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px;
  margin: 16px 0; font-size: 14px; color: var(--muted);
}
.seg {
  font: 600 13.5px/1 inherit; padding: 9px 13px; border-radius: 10px; cursor: pointer;
  background: #1d2437; color: var(--text); border: 1px solid var(--line);
}
.seg:hover { border-color: var(--accent); }
.seg.active { background: var(--accent); color: #0b0e14; border-color: var(--accent); font-weight: 800; }
.pad .seg { flex: 1; }
.pad__hint { font-size: 12.5px; color: var(--muted); align-self: center; margin-right: 2px; }

/* --- таблица граней --- */
.nt { width: 100%; border-collapse: collapse; margin: 6px 0 18px; font-size: 14.5px; }
.nt th {
  text-align: left; padding: 9px 12px; color: var(--muted); font-size: 12px;
  text-transform: uppercase; letter-spacing: .08em; border-bottom: 1px solid var(--line);
}
.nt td { padding: 10px 12px; border-bottom: 1px solid #1d2437; }
.nt tr:last-child td { border-bottom: 0; }
.ntl, .ntr {
  font: 800 17px/1 ui-monospace, Consolas, monospace; color: var(--accent);
}
.muted { color: var(--muted); font-size: 13px; }
@media (max-width: 620px) {
  .nt th:nth-child(4), .nt td:nth-child(4) { display: none; }
}

/* --- словарик --- */
.gloss { display: grid; gap: 10px; }
.gloss__item {
  background: var(--card-2); border: 1px solid var(--line); border-radius: 12px; padding: 13px 16px;
}
.gloss__item b { color: var(--accent); }
.gloss__item .en { color: var(--muted); font-size: 13px; font-style: italic; }
.gloss__item p { margin: 5px 0 0; font-size: 14.6px; color: #c3cde2; }

/* --- таблица нотации --- */
.notation { display: grid; grid-template-columns: repeat(auto-fill, minmax(155px, 1fr)); gap: 10px; }
.nkey {
  background: var(--card-2); border: 1px solid var(--line); border-radius: 12px;
  padding: 12px; cursor: pointer; text-align: left; color: var(--text);
}
.nkey:hover { border-color: var(--accent); }
.nkey b { font: 800 19px/1 ui-monospace, Consolas, monospace; color: var(--accent); }
.nkey span { display: block; font-size: 13px; color: var(--muted); margin-top: 5px; }

/* --- чек-лист прогресса --- */
.progress { display: flex; align-items: center; gap: 10px; margin-top: 14px; font-size: 14px; color: var(--muted); }
.progress input { width: 18px; height: 18px; accent-color: var(--accent-2); }

.track { height: 6px; border-radius: 99px; background: #1d2437; overflow: hidden; margin-top: 10px; }
.track i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent-2), var(--accent)); transition: width .4s ease; }

/* --- FAQ --- */
details {
  background: var(--card-2); border: 1px solid var(--line);
  border-radius: 12px; padding: 12px 16px; margin-bottom: 10px;
}
details[open] { border-color: #33405f; }
summary { cursor: pointer; font-weight: 650; }
summary::marker { color: var(--accent); }
details p { margin: 10px 0 2px; color: #c3cde2; font-size: 15px; }

kbd {
  font: 600 12px/1 ui-monospace, Consolas, monospace; padding: 3px 6px;
  border-radius: 5px; background: #1d2437; border: 1px solid var(--line); color: var(--text);
}

footer.site {
  max-width: var(--maxw); margin: 0 auto; padding: 0 20px 60px;
  color: var(--muted); font-size: 14px;
}

/* --- анимации появления --- */
.reveal { opacity: 0; transform: translateY(14px); transition: opacity .5s ease, transform .5s ease; }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

.pulse { animation: pulse 1.1s ease; }
@keyframes pulse { 0% { box-shadow: 0 0 0 0 rgba(250,204,21,.55); } 100% { box-shadow: 0 0 0 20px rgba(250,204,21,0); } }

/* ================= ТЕЛЕФОН: плотнее текст, крупнее кнопки ================= */
@media (max-width: 680px) {
  body { font-size: 15.5px; line-height: 1.6; }
  html { scroll-padding-top: 62px; }

  .layout { padding: 14px 12px 40px; gap: 14px; }
  .topbar__in { padding: 8px 12px; gap: 10px; }

  .hero { padding: 20px 16px; border-radius: 18px; margin-bottom: 16px; }
  .hero h1 { font-size: 26px; }
  .hero p.lead { font-size: 16px; }

  section.step, section.block { padding: 18px 16px; margin-bottom: 14px; border-radius: 14px; }
  section.step { border-left-width: 3px; }
  h2 { font-size: 22px; }
  h3 { font-size: 17.5px; margin-top: 18px; }

  ul, ol { padding-left: 1.1em; }
  li { margin: .45em 0; }

  .case { padding: 14px; border-radius: 12px; }
  .case__title { font-size: 15.5px; }
  .case p { font-size: 14.5px; }
  .case__foot { gap: 8px; }
  .case__foot button.demo { flex: 1; justify-content: center; min-height: 44px; }
  .alg { font-size: 14px; padding: 8px 10px; }
  .alg.small { font-size: 13px; }

  .note, .warn, .tip { padding: 12px 14px; font-size: 14.5px; }
  .step__goal { padding: 12px 14px; }
  .badges { gap: 6px; }
  .badge { font-size: 12px; padding: 5px 9px; }

  .notation { grid-template-columns: repeat(auto-fill, minmax(128px, 1fr)); gap: 8px; }
  .nkey { padding: 10px; min-height: 62px; }
  .nkey b { font-size: 17px; }
  .nkey span { font-size: 12px; }

  .diagrams { gap: 12px; justify-content: center; }
  .switcher { gap: 6px; }
  .switcher .seg { flex: 1; min-width: 132px; min-height: 44px; }

  details { padding: 11px 14px; }
  .gloss__item { padding: 12px 14px; }
  .nt td, .nt th { padding: 8px 8px; }

  footer.site { padding-left: 12px; padding-right: 12px; font-size: 13px; }
}

/* совсем узкие экраны */
@media (max-width: 380px) {
  .hero h1 { font-size: 23px; }
  .keycap { padding: 11px 10px; font-size: 13px; }
  .notation { grid-template-columns: 1fr 1fr; }
}