/* ============================================================
   Курс по нейросетям — нейтральный учебный стиль (этап 1)
   ============================================================ */

:root {
  --bg: #f4f6fb;
  --card: #ffffff;
  --line: #e3e8f2;
  --ink: #232a3b;
  --body: #333b4f;
  --muted: #66707f;
  --accent: #2f5bff;
  --accent-dark: #1e41c9;
  --soft: #eaf0ff;
  --soft-line: #cdd9fb;
  --ok: #0f8a5f;
  --ok-soft: #e6f6ef;
  --ok-line: #cdebe0;
  --warn: #a8450f;
  --warn-soft: #fdf0e7;
  --warn-line: #f3d9c8;
  --radius: 18px;
  --shadow: 0 1px 2px rgba(20, 30, 60, .06), 0 14px 34px -20px rgba(20, 30, 60, .3);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, "Roboto", Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
}

.hidden { display: none !important; }

/* Полоса прогресса чтения */
#progressbar {
  position: fixed;
  top: 0; left: 0;
  height: 4px;
  width: 0;
  background: linear-gradient(90deg, var(--accent), #7aa0ff);
  z-index: 60;
  transition: width .08s linear;
}

/* ---------------- Экран «Доступ закрыт» ---------------- */

.locked {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background:
    radial-gradient(700px 320px at 15% 0%, rgba(47, 91, 255, .10), transparent 60%),
    radial-gradient(700px 320px at 85% 100%, rgba(122, 160, 255, .12), transparent 60%),
    var(--bg);
}

.locked-card {
  max-width: 540px;
  text-align: center;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 46px 34px;
  box-shadow: var(--shadow);
}

.locked-card .ico { font-size: 54px; }
.locked-card h1 { margin: 14px 0 10px; font-size: 30px; }
.locked-card p { margin: 0 0 10px; color: var(--body); font-size: 16.5px; }
.locked-card .muted { color: var(--muted); }
.locked-card .hint {
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px dashed var(--line);
  color: var(--muted);
  font-size: 14px;
}

.small { font-size: 14px; }

/* ---------------- Шапка и навигация ---------------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}

.topbar-inner {
  max-width: 1040px;
  margin: 0 auto;
  padding: 10px 20px;
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 15.5px;
  white-space: nowrap;
}

.brand .dot {
  width: 30px; height: 30px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), #7aa0ff);
  display: grid;
  place-items: center;
  font-size: 16px;
  color: #fff;
  box-shadow: 0 4px 12px -4px rgba(47, 91, 255, .6);
}

.nav {
  display: flex;
  gap: 2px;
  flex-wrap: wrap;
  margin-left: auto;
}

.nav a {
  text-decoration: none;
  color: var(--muted);
  font-size: 13.5px;
  padding: 6px 11px;
  border-radius: 999px;
  transition: background .15s, color .15s;
}

.nav a:hover { background: var(--soft); color: var(--accent); }
.nav a.active { background: var(--accent); color: #fff; }

/* ---------------- Общие элементы ---------------- */

.wrap {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Герой */
.hero {
  text-align: center;
  padding: 64px 0 58px;
  background:
    radial-gradient(900px 340px at 18% -12%, rgba(47, 91, 255, .11), transparent 62%),
    radial-gradient(820px 320px at 85% -6%, rgba(122, 160, 255, .15), transparent 62%),
    var(--bg);
}

.badge {
  display: inline-block;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 16px;
  font-size: 14px;
  color: var(--muted);
  box-shadow: 0 4px 14px -10px rgba(20, 30, 60, .35);
}

.hero h1 {
  margin: 20px 0 12px;
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1.15;
  letter-spacing: -.5px;
}

.hero .lead {
  max-width: 700px;
  margin: 0 auto;
  font-size: 19px;
  color: var(--body);
}

.chips {
  margin-top: 24px;
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
}

.chip {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 15px;
  font-size: 14.5px;
  color: var(--ink);
}

/* Карточки уроков */
.lesson { margin: 24px auto; }

.lesson-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 34px clamp(20px, 4.4vw, 46px);
  box-shadow: var(--shadow);
}

.step-head {
  display: flex;
  align-items: flex-start;
  gap: 18px;
  margin-bottom: 16px;
}

.step-num {
  flex: none;
  width: 54px; height: 54px;
  border-radius: 16px;
  background: var(--soft);
  color: var(--accent);
  font-weight: 800;
  font-size: 21px;
  display: grid;
  place-items: center;
}

.lesson h2 { margin: 0 0 4px; font-size: clamp(23px, 3vw, 31px); line-height: 1.2; }
.lesson .sub { margin: 0; color: var(--muted); font-size: 16px; }
.lesson .body p { color: var(--body); }

.body h3 {
  margin: 26px 0 12px;
  font-size: 18px;
}

/* Карточки-умения */
.skills {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 14px;
  margin: 22px 0;
}

.skill {
  background: #f8fafd;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
}

.skill b { display: block; font-size: 16px; margin-bottom: 4px; }
.skill p { margin: 0; font-size: 14.5px; color: var(--muted); }

/* Заметки */
.note {
  border-radius: 14px;
  padding: 16px 18px;
  margin: 20px 0;
}

.note strong { display: block; margin-bottom: 4px; }
.note .nt { margin: 0; font-size: 15.5px; }

.note.warn { background: var(--warn-soft); border: 1px solid var(--warn-line); }
.note.warn strong { color: var(--warn); }
.note.tip  { background: var(--ok-soft); border: 1px solid var(--ok-line); }
.note.tip strong { color: var(--ok); }
.note.info { background: var(--soft); border: 1px solid var(--soft-line); }
.note.info strong { color: var(--accent-dark); }

/* Словарик */
.terms {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 12px;
  margin-top: 10px;
}

.term {
  background: #fff;
  border: 1px dashed var(--line);
  border-radius: 12px;
  padding: 14px 16px;
}

.term b { display: block; font-size: 15px; margin-bottom: 2px; }
.term span { color: var(--muted); font-size: 14.5px; }

/* Шаги */
.steps {
  list-style: none;
  counter-reset: step;
  padding: 0;
  margin: 20px 0;
  display: grid;
  gap: 12px;
}

.steps li {
  position: relative;
  background: #f8fafd;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 16px 18px 16px 66px;
  color: var(--body);
  counter-increment: step;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 18px; top: 16px;
  width: 32px; height: 32px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-weight: 700;
  font-size: 16px;
  display: grid;
  place-items: center;
}

.steps b { display: block; color: var(--ink); margin-bottom: 2px; }

/* Чат-диалог */
.chat {
  max-width: 680px;
  margin: 26px auto;
  display: grid;
  gap: 14px;
}

.bubble {
  max-width: 86%;
  padding: 13px 17px;
  border-radius: 17px;
  font-size: 15.5px;
  white-space: pre-line;
}

.bubble.user {
  justify-self: end;
  background: var(--accent);
  color: #fff;
  border-bottom-right-radius: 5px;
}

.bubble.bot {
  justify-self: start;
  background: #f2f4f9;
  border: 1px solid var(--line);
  border-bottom-left-radius: 5px;
}

.chat-cap {
  max-width: 680px;
  margin: 4px auto 0;
  text-align: center;
  color: var(--muted);
  font-size: 13.5px;
}

/* Заготовки разделов следующего этапа */
.lesson-card.soon {
  border: 2px dashed #c9d4ea;
  background: #fbfcff;
  box-shadow: none;
}

.soon-note { margin: 6px 0; }

.soon ul {
  margin: 6px 0 0;
  padding-left: 20px;
  color: var(--muted);
}

.soon li { margin: 4px 0; }

/* Подвал */
.footer {
  margin-top: 42px;
  border-top: 1px solid var(--line);
  background: #fff;
  padding: 26px 20px 32px;
  text-align: center;
  color: var(--muted);
  font-size: 14.5px;
}

.footer p { margin: 4px 0; }

/* ---------------- Урок 4: карточки с запросами ---------------- */

.prompts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(330px, 1fr));
  gap: 16px;
  margin: 22px 0 8px;
}

.prompt-card {
  background: #f8fafd;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.prompt-head {
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.p-ico {
  flex: none;
  width: 40px; height: 40px;
  border-radius: 11px;
  background: var(--soft);
  color: var(--accent);
  display: grid;
  place-items: center;
  font-size: 17px;
}

.p-title b { display: block; font-size: 16px; }
.p-title > span { color: var(--muted); font-size: 13.5px; }

.prompt-text {
  background: #fff;
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: 10px;
  padding: 11px 14px;
  font-size: 14.5px;
  color: var(--body);
}

.copy-btn {
  align-self: flex-start;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 14px;
  font: inherit;
  font-size: 13.5px;
  font-weight: 600;
  color: var(--accent-dark);
  cursor: pointer;
  transition: background .15s, color .15s, border-color .15s;
}

.copy-btn:hover { background: var(--soft); border-color: var(--soft-line); }
.copy-btn.copied { background: var(--ok-soft); border-color: var(--ok-line); color: var(--ok); }

/* ---------------- Урок 5: сравнение запросов ---------------- */

.vs {
  display: grid;
  grid-template-columns: 1fr 1.3fr;
  gap: 14px;
  margin: 14px 0 8px;
}

.vs-card {
  border-radius: 14px;
  padding: 16px 18px;
  font-size: 15px;
}

.vs-card.bad {
  background: var(--warn-soft);
  border: 1px solid var(--warn-line);
}

.vs-card.good {
  background: var(--ok-soft);
  border: 1px solid var(--ok-line);
}

.vs-head {
  font-weight: 700;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 7px;
}

.vs-card.bad .vs-head { color: var(--warn); }
.vs-card.good .vs-head { color: var(--ok); }

.vs-q {
  font-style: italic;
  margin-bottom: 8px;
}

.vs-card p { margin: 0; color: var(--muted); font-size: 13.5px; }

.mini-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 10px;
}

.mini-chips span {
  background: #fff;
  border: 1px solid var(--ok-line);
  border-radius: 999px;
  padding: 5px 12px;
  font-size: 13px;
  color: var(--ok);
}

/* ---------------- Приложения для телефона (Урок 6) ---------------- */

.store-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 14px 0 6px;
}

.store-btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  text-decoration: none;
  color: #fff;
  border-radius: 12px;
  padding: 11px 18px;
  font-weight: 600;
  font-size: 14.5px;
  transition: filter .15s, transform .15s, box-shadow .15s;
}

.store-btn:hover {
  transform: translateY(-1px);
  filter: brightness(1.08);
}

.store-btn .fa-google-play,
.store-btn .fa-apple {
  color: #fff;
  font-size: 19px;
}

.store-btn.gp {
  background: linear-gradient(135deg, #0f9d58, #0bb268);
  box-shadow: 0 8px 18px -12px rgba(15, 157, 88, .6);
}

.store-btn.ap {
  background: linear-gradient(135deg, #0d0d0d, #2b2b2b);
  box-shadow: 0 8px 18px -12px rgba(0, 0, 0, .5);
}

.store-note {
  margin-top: 12px;
  color: var(--muted);
  font-size: 13.5px;
  display: flex;
  align-items: flex-start;
  gap: 7px;
}

.store-note i { margin-top: 3px; color: var(--accent); }

/* ---------------- Урок 6–7: чек-листы ---------------- */

.linkrow {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 6px 0 18px;
}

.extlink {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  background: var(--soft);
  color: var(--accent-dark);
  border: 1px solid var(--soft-line);
  border-radius: 999px;
  padding: 8px 16px;
  font-weight: 600;
  font-size: 14.5px;
  transition: background .15s;
}

.extlink:hover { background: #dde7ff; }

.checklist {
  background: #f8fafd;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
  margin: 0 0 18px;
}

.checklist-head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.checklist-head b { font-size: 16px; }
.checklist-progress { color: var(--muted); font-size: 13.5px; font-weight: 600; }

.check {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 10px 8px;
  border-top: 1px solid var(--line);
  cursor: pointer;
}

.check input[type="checkbox"] {
  flex: none;
  width: 19px; height: 19px;
  margin-top: 3px;
  accent-color: var(--accent);
  cursor: pointer;
}

.check-body { display: block; }
.check-body b { display: block; font-size: 15.5px; margin-bottom: 2px; }
.check-body > span { color: var(--body); font-size: 14.5px; }

.check-body .hint {
  display: block;
  color: var(--muted);
  font-size: 13.5px;
  font-style: normal;
  margin-top: 3px;
}

.check a { color: var(--accent); }
.check:has(input:checked) .check-body > span { color: var(--muted); }
.check:has(input:checked) .check-body b { color: var(--muted); text-decoration: line-through; }

.done-banner {
  margin-top: 12px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
  background: var(--ok-soft);
  border: 1px solid var(--ok-line);
  color: var(--ok);
  border-radius: 12px;
  padding: 12px 16px;
  font-weight: 600;
  font-size: 15px;
}

.done-banner i { margin-top: 3px; }

/* ---------------- FAQ: аккордеон ---------------- */

.faq-list {
  display: grid;
  gap: 10px;
  margin-top: 8px;
}

.faq-item {
  background: #f8fafd;
  border: 1px solid var(--line);
  border-radius: 12px;
  overflow: hidden;
}

.faq-q {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 18px;
  background: none;
  border: none;
  font: inherit;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--ink);
  text-align: left;
  cursor: pointer;
}

.faq-q:hover { background: var(--soft); }
.faq-q i { color: var(--muted); transition: transform .2s; font-size: 14px; }
.faq-q[aria-expanded="true"] i { transform: rotate(180deg); }

.faq-a { display: none; }

.faq-a.open {
  display: block;
  padding: 0 18px 16px;
  border-top: 1px dashed var(--line);
}

.faq-a p { margin: 12px 0 0; color: var(--body); font-size: 15px; }

/* ---------------- Чего не стоит делать ---------------- */

.rules {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 14px;
  margin: 10px 0;
}

.rule {
  background: var(--warn-soft);
  border: 1px solid var(--warn-line);
  border-radius: 14px;
  padding: 18px;
}

.r-ico {
  display: grid;
  place-items: center;
  width: 40px; height: 40px;
  border-radius: 11px;
  background: #fff;
  color: var(--warn);
  font-size: 17px;
  margin-bottom: 10px;
}

.rule b { display: block; font-size: 15.5px; margin-bottom: 4px; }
.rule p { margin: 0; color: var(--body); font-size: 14.5px; }

/* ---------------- Иконки Font Awesome ---------------- */

.locked-card .ico i { font-size: 44px; color: var(--accent); }
.brand .dot i { font-size: 15px; color: #fff; }
.nav a i { margin-right: 5px; font-size: .95em; }
.chip i { margin-right: 7px; color: var(--accent); }
.skill b i { margin-right: 7px; color: var(--accent); }
.note strong i { margin-right: 8px; }
.step-num i { font-size: 22px; }
.soon-note i { margin-right: 6px; color: var(--muted); }
.footer .fa-heart { color: #e2557d; margin: 0 3px; }

/* ---------------- Адаптив ---------------- */

@media (max-width: 760px) {
  .nav { margin-left: 0; width: 100%; }
  .hero { padding: 44px 0 40px; }
  .step-head { gap: 14px; }
}