:root {
    --bg: #f4f6fc;
    --surface: #ffffff;
    --surface-2: #eef1fa;
    --fg: #0e1330;
    --muted: #4d5588;
    --subtle: #7a82ad;
    --line: #dde1f2;
    --accent: #0a6fd6;
    --accent-soft: #e3effc;
    --good: #117a3e;
    --good-soft: #e3f4ea;
    --code-bg: #0e1330;
    --code-fg: #dce3ff;
    --radius: 20px;
    --font: Rubik, system-ui, -apple-system, "Segoe UI", sans-serif;
    --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
    margin: 0;
    font-family: var(--font);
    font-size: 16px;
    line-height: 1.55;
    color: var(--fg);
    background: var(--bg);
}

a { color: var(--accent); text-decoration: none; }

h1, h2, h3, p { margin: 0; }

.wrap {
    max-width: 1160px;
    margin: 0 auto;
    padding: 0 24px;
}

.accent { color: var(--accent); }
.muted { color: var(--muted); }
.small { font-size: 14px; }

.eyebrow {
    margin: 0 0 10px;
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    color: var(--accent);
}

h1 {
    font-size: clamp(36px, 5vw, 56px);
    line-height: 1.06;
    letter-spacing: -0.03em;
    font-weight: 700;
}

.h2 {
    font-size: clamp(26px, 3.2vw, 36px);
    line-height: 1.15;
    letter-spacing: -0.02em;
    font-weight: 700;
}

h2, h3 { font-size: 18px; line-height: 1.3; font-weight: 600; }

.lead {
    margin-top: 18px;
    font-size: 18px;
    color: var(--muted);
    max-width: 36em;
}

.card {
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius);
}

.pill {
    display: inline-flex;
    align-items: center;
    font-size: 12px;
    font-weight: 600;
    padding: 4px 10px;
    border-radius: 999px;
    background: var(--surface-2);
    color: var(--muted);
}

.pill-accent {
    background: var(--accent-soft);
    color: var(--accent);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 13px 22px;
    border-radius: 999px;
    background: var(--accent);
    color: #fff;
    font-weight: 600;
    font-size: 15px;
    line-height: 1;
    transition: background 0.2s, transform 0.2s;
}

.btn:hover, .btn:focus-visible {
    background: #085bb0;
    color: #fff;
    transform: translateY(-1px);
}

.btn-sm { padding: 9px 16px; font-size: 14px; }

.cloud { width: 22px; height: 16px; }

.bar {
    position: sticky;
    top: 0;
    z-index: 10;
    background: #fff;
    border-bottom: 1px solid var(--line);
}

.bar-inner {
    display: flex;
    align-items: center;
    height: 68px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    color: var(--fg);
    font-weight: 700;
}

.brand:hover { color: var(--fg); }

.mark { width: 28px; height: 18px; color: var(--accent); }

.brand-name { font-size: 18px; letter-spacing: -0.02em; }

.bar .btn { margin-left: auto; }

.stage {
    position: relative;
    overflow: hidden;
    padding: 72px 0 36px;
    background:
        radial-gradient(900px 420px at 85% 0%, rgba(10, 111, 214, 0.1), transparent 60%),
        radial-gradient(700px 380px at 0% 100%, rgba(201, 106, 0, 0.07), transparent 60%),
        var(--bg);
}

.field {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.hero-grid, .areas, .section, .cta-band { position: relative; z-index: 1; }

.hero-grid {
    display: grid;
    grid-template-columns: 1.05fr 1fr;
    gap: 56px;
    align-items: center;
}

.hero-copy .pill { margin-bottom: 20px; }

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 16px;
    margin-top: 28px;
}

.facts {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
    gap: 28px;
    margin: 40px 0 0;
    padding: 24px 0 0;
    border-top: 1px solid var(--line);
    font-size: 14px;
    color: var(--muted);
}

.facts strong { color: var(--fg); }

.mock {
    background: var(--code-bg);
    border-radius: var(--radius);
    box-shadow: 0 30px 60px rgba(14, 19, 48, 0.22);
    color: var(--code-fg);
    overflow: hidden;
}

.mock-bar {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 14px 18px;
    background: rgba(255, 255, 255, 0.04);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}

.mock-bar span {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.18);
}

.mock-bar p {
    margin-left: 10px;
    font-size: 13px;
    color: rgba(220, 227, 255, 0.7);
}

.mock-problem {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    padding: 18px 20px 0;
}

.mock-title { font-size: 16px; font-weight: 600; color: #fff; }

.mock-code {
    margin: 0;
    padding: 18px 20px;
    font-family: var(--mono);
    font-size: 13px;
    line-height: 1.7;
    overflow-x: auto;
    color: var(--code-fg);
}

.mock-code .k { color: #7cc4ff; }

.mock-result {
    display: flex;
    gap: 12px;
    align-items: center;
    margin: 0 16px 16px;
    padding: 14px 16px;
    border-radius: 12px;
    background: rgba(17, 122, 62, 0.22);
    border: 1px solid rgba(76, 200, 128, 0.35);
}

.tick {
    width: 28px;
    height: 28px;
    flex: none;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: #1f9d55;
    color: #fff;
    font-weight: 700;
}

.mock-result-title { font-size: 14px; font-weight: 600; color: #fff; }
.mock-result-sub { font-size: 13px; color: rgba(220, 227, 255, 0.75); }

.areas {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-top: 56px;
}

.area {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 20px;
    color: var(--fg);
    transition: border-color 0.2s, transform 0.2s;
}

.area:hover, .area:focus-visible {
    color: var(--fg);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.area p { flex: 1; }

.kicker {
    font-size: 12px;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--accent);
}

.go { margin-top: 8px; font-size: 14px; font-weight: 600; color: var(--accent); }

.section { padding: 80px 0; background: var(--surface); }
.section-alt { background: var(--bg); }

.steps, .tracks {
    display: grid;
    gap: 16px;
    margin-top: 36px;
}

.steps { grid-template-columns: repeat(3, 1fr); gap: 20px; }
.tracks { grid-template-columns: repeat(4, 1fr); }

.step, .track {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding: 28px;
}

.track { padding: 22px; }
.step p, .track p { flex: 1; }

.step-num {
    display: inline-grid;
    place-items: center;
    width: 40px;
    height: 40px;
    margin-bottom: 8px;
    border-radius: 12px;
    background: var(--accent-soft);
    color: var(--accent);
    font-weight: 700;
    font-size: 14px;
}

.track-top {
    width: 100%;
    display: flex;
    justify-content: space-between;
    gap: 12px;
}

.lock {
    width: 28px;
    height: 28px;
    display: grid;
    place-items: center;
    border-radius: 8px;
    background: var(--surface-2);
    color: var(--subtle);
}

.lock svg { width: 14px; height: 14px; }

.access-grid {
    display: grid;
    grid-template-columns: 1fr 1.1fr;
    gap: 48px;
    align-items: center;
}

.access { list-style: none; margin: 0; padding: 8px 24px; }

.access li {
    display: flex;
    gap: 12px;
    padding: 16px 0;
    border-bottom: 1px solid var(--line);
}

.access li:last-child { border-bottom: 0; }

.check {
    flex: none;
    width: 24px;
    height: 24px;
    display: grid;
    place-items: center;
    border-radius: 50%;
    background: var(--good-soft);
    color: var(--good);
    font-size: 13px;
    font-weight: 700;
}

.cta-band { background: var(--code-bg); padding: 56px 0; }

.cta-inner {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 24px;
}

.cta-title {
    margin-bottom: 6px;
    font-size: 28px;
    font-weight: 700;
    letter-spacing: -0.02em;
    color: #fff;
}

.cta-sub { color: rgba(220, 227, 255, 0.75); }

.cta-btn, .cta-btn:hover, .cta-btn:focus-visible {
    background: #fff;
    color: var(--fg);
}

.cta-btn:hover, .cta-btn:focus-visible { background: var(--accent-soft); }

.footer {
    background: var(--surface);
    border-top: 1px solid var(--line);
    padding: 28px 0;
}

.footer-inner {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 16px;
}

.footer .brand-name { margin-bottom: 2px; font-size: 16px; font-weight: 700; }

.meta {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 2px;
}

.meta a { color: var(--fg); font-weight: 500; }
.meta a:hover { color: var(--accent); }

@media (max-width: 1000px) {
    .hero-grid, .access-grid { grid-template-columns: 1fr; }
    .areas, .tracks { grid-template-columns: repeat(2, 1fr); }
    .access-grid { gap: 24px; }
}

.nav { display: flex; gap: 4px; margin-left: 12px; }
.nav-link { padding: 8px 12px; border-radius: 999px; color: var(--muted); font-weight: 500; }
.nav-link.is-active, .nav-link:hover { color: var(--accent); background: var(--accent-soft); }
.session-side { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.points-pill, .who { font-size: 14px; font-weight: 600; }
.narrow { max-width: 40rem; }
.editor-layout { display: grid; grid-template-columns: 280px minmax(0, 1fr); gap: 24px; align-items: start; }
.problem-list, .lesson-nav { display: flex; flex-direction: column; gap: 8px; }
.problem-btn, .option {
    display: flex; gap: 10px; width: 100%; text-align: left; padding: 12px 14px;
    border: 1px solid var(--line); border-radius: 12px; background: #fff; color: var(--fg);
    font: inherit; cursor: pointer;
}
.problem-btn.is-on, .option.is-on { border-color: var(--accent); background: var(--accent-soft); }
.option.is-right { border-color: var(--good); background: var(--good-soft); }
.option.is-wrong { border-color: #c22a4b; background: #fbe6eb; }
.problem-card { padding: 24px; display: flex; flex-direction: column; gap: 12px; }
.problem-card .h2, .problem-card h2 { font-size: 28px; }
.editor-box { height: 420px; margin-top: 16px; border-radius: 16px; overflow: hidden; }
.run-row { display: flex; gap: 16px; align-items: center; margin-top: 12px; }
.result { margin: 0; white-space: pre-wrap; }
.back { font-weight: 600; }
.lesson-code { background: var(--code-bg); color: var(--code-fg); padding: 16px; border-radius: 12px; overflow: auto; }
.why { min-height: 1.4em; }
.map-tabs { display: flex; gap: 8px; margin: 12px 0; }
.map-frame { width: 100%; height: 640px; border: 0; border-radius: 16px; background: #fff; }
.board-list { list-style: none; padding: 0; }
.board-list li { display: flex; justify-content: space-between; padding: 12px 0; border-bottom: 1px solid var(--line); }
.options { display: flex; flex-direction: column; gap: 8px; margin: 12px 0; }

@media (max-width: 900px) {
    .editor-layout, .nav { display: block; }
    .session-side { margin: 8px 0 12px; }
}

@media (max-width: 700px) {
    .stage { padding: 48px 0 28px; }
    .section { padding: 56px 0; }
    .areas, .steps, .tracks { grid-template-columns: 1fr; }
    .meta { align-items: flex-start; }
}