:root {
    --bg: #f3f7fc;
    --surface: #ffffff;
    --surface-soft: #e9f1fb;
    --ink: #24324a;
    --muted: #65728a;
    --line: #c9d6e7;
    --accent: #5b57d9;
    --accent-2: #117f9f;
    --accent-soft: #e6e8ff;
    --focus: #d15b93;
    --max: 1180px;
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    line-height: 1.7;
}

a {
    color: var(--accent);
    text-decoration-thickness: 1px;
    text-underline-offset: 0.18em;
}

a:hover {
    color: var(--accent-2);
}

a:active {
    transform: translateY(1px);
}

a:focus-visible,
button:focus-visible {
    outline: 3px solid var(--focus);
    outline-offset: 4px;
}

.site-header {
    position: sticky;
    top: 0;
    z-index: 20;
    border-bottom: 1px solid rgba(201, 214, 231, 0.9);
    background: rgba(243, 247, 252, 0.94);
    backdrop-filter: blur(12px);
}

.header-inner {
    width: min(calc(100% - 40px), var(--max));
    min-height: 74px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 12px;
    color: var(--ink);
    font-weight: 800;
    letter-spacing: 0.04em;
    text-decoration: none;
    white-space: nowrap;
}

.brand-mark {
    width: 38px;
    height: 38px;
    display: grid;
    place-items: center;
    border: 1px solid var(--accent);
    background: var(--accent-soft);
    color: var(--accent);
    font-size: 13px;
    letter-spacing: 0.08em;
}

.main-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: 8px 18px;
}

.main-nav a {
    color: var(--muted);
    font-size: 14px;
    font-weight: 700;
    text-decoration: none;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
    color: var(--accent);
}

main {
    overflow: hidden;
}

.hero {
    position: relative;
    border-bottom: 1px solid var(--line);
    background:
        linear-gradient(90deg, rgba(91, 87, 217, 0.09) 1px, transparent 1px),
        linear-gradient(rgba(17, 127, 159, 0.07) 1px, transparent 1px),
        var(--surface);
    background-size: 42px 42px;
}

.hero::after {
    content: "";
    position: absolute;
    right: -120px;
    top: 54px;
    width: 380px;
    height: 380px;
    border: 1px solid rgba(91, 87, 217, 0.35);
    border-radius: 50%;
    box-shadow: inset 0 0 0 68px rgba(17, 127, 159, 0.04), inset 0 0 0 136px rgba(91, 87, 217, 0.035);
    pointer-events: none;
}

.hero-inner {
    position: relative;
    z-index: 1;
    width: min(calc(100% - 40px), var(--max));
    min-height: 520px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: minmax(0, 1.45fr) minmax(260px, 0.55fr);
    gap: 64px;
    align-items: end;
    padding: 94px 0 82px;
}

.kicker {
    margin: 0 0 18px;
    color: var(--accent-2);
    font-size: 13px;
    font-weight: 800;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}

h1,
h2,
h3,
p {
    overflow-wrap: anywhere;
}

h1 {
    max-width: 900px;
    margin: 0;
    font-size: 40px;
    line-height: 1.06;
    letter-spacing: -0.035em;
}

h2 {
    margin: 0 0 22px;
    font-size: 28px;
    line-height: 1.18;
    letter-spacing: -0.02em;
}

h3 {
    margin: 0 0 12px;
    font-size: 20px;
    line-height: 1.25;
}

p {
    margin: 0 0 18px;
    font-size: 16px;
}

.hero-lead {
    max-width: 760px;
    margin-top: 28px;
    color: var(--muted);
    font-size: 19px;
    line-height: 1.65;
}

.hero-index {
    align-self: end;
    border-top: 2px solid var(--accent);
    padding-top: 18px;
}

.hero-index span {
    display: block;
    color: var(--muted);
    font-size: 12px;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.hero-index strong {
    display: block;
    margin-top: 5px;
    font-size: 18px;
}

.layout {
    width: min(calc(100% - 40px), var(--max));
    margin: 0 auto;
    display: grid;
    grid-template-columns: 180px minmax(0, 1fr);
    gap: 64px;
    padding: 78px 0 96px;
}

.section-rail {
    position: relative;
}

.rail-sticky {
    position: sticky;
    top: 112px;
    display: grid;
    gap: 10px;
}

.rail-label {
    color: var(--muted);
    font-size: 12px;
    font-weight: 800;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.rail-line {
    width: 100%;
    height: 1px;
    background: var(--line);
}

.rail-code {
    color: var(--accent);
    font-size: 38px;
    line-height: 1;
    font-weight: 800;
    letter-spacing: -0.05em;
}

.content {
    min-width: 0;
}

.intro-block {
    max-width: 790px;
    margin-bottom: 64px;
}

.article-section {
    display: grid;
    grid-template-columns: minmax(220px, 0.38fr) minmax(0, 0.62fr);
    gap: 44px;
    padding: 44px 0;
    border-top: 1px solid var(--line);
}

.article-section p {
    color: var(--muted);
}

.article-section p:last-child,
.intro-block p:last-child {
    margin-bottom: 0;
}

.atlas {
    border-top: 1px solid var(--line);
    padding: 64px 0 0;
}

.atlas-head {
    max-width: 680px;
    margin-bottom: 26px;
}

.atlas-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1px;
    background: var(--line);
    border: 1px solid var(--line);
}

.atlas-card {
    min-height: 185px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    gap: 28px;
    padding: 28px;
    background: var(--surface);
    color: var(--ink);
    text-decoration: none;
}

.atlas-card:hover {
    background: var(--surface-soft);
    color: var(--ink);
}

.card-no {
    color: var(--accent-2);
    font-size: 12px;
    font-weight: 800;
    letter-spacing: 0.12em;
}

.atlas-card strong {
    display: block;
    margin-bottom: 8px;
    font-size: 20px;
}

.atlas-card p {
    margin: 0;
    color: var(--muted);
    font-size: 15px;
}

.glossary {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 1px;
    margin-top: 34px;
    border: 1px solid var(--line);
    background: var(--line);
}

.glossary article {
    min-height: 170px;
    padding: 26px;
    background: var(--surface);
}

.glossary article p {
    color: var(--muted);
    margin-bottom: 0;
}

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

.footer-inner {
    width: min(calc(100% - 40px), var(--max));
    min-height: 150px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 30px;
    align-items: center;
}

.footer-title {
    margin: 0;
    font-size: 17px;
    font-weight: 800;
}

.footer-note {
    margin: 5px 0 0;
    color: var(--muted);
    font-size: 14px;
}

.footer-link {
    font-weight: 800;
}

@media (max-width: 900px) {
    .header-inner {
        align-items: flex-start;
        flex-direction: column;
        padding: 16px 0;
    }

    .main-nav {
        justify-content: flex-start;
    }

    .hero-inner {
        min-height: auto;
        grid-template-columns: 1fr;
        gap: 48px;
        padding: 74px 0 60px;
    }

    .hero::after {
        right: -220px;
    }

    .layout {
        grid-template-columns: 1fr;
        gap: 28px;
        padding-top: 54px;
    }

    .section-rail {
        display: none;
    }
}

@media (max-width: 680px) {
    .header-inner,
    .hero-inner,
    .layout,
    .footer-inner {
        width: min(calc(100% - 28px), var(--max));
    }

    .brand-text {
        white-space: normal;
    }

    .main-nav {
        gap: 8px 14px;
    }

    h1 {
        font-size: 40px;
    }

    h2 {
        font-size: 28px;
    }

    p {
        font-size: 16px;
    }

    .hero-lead {
        font-size: 17px;
    }

    .article-section {
        grid-template-columns: 1fr;
        gap: 16px;
        padding: 34px 0;
    }

    .atlas-grid,
    .glossary {
        grid-template-columns: 1fr;
    }

    .footer-inner {
        grid-template-columns: 1fr;
        padding: 34px 0;
    }
}

@media (max-width: 420px) {
    .brand {
        align-items: flex-start;
    }

    .brand-mark {
        flex: 0 0 auto;
    }

    .main-nav a {
        font-size: 13px;
    }

    .hero-inner {
        padding-top: 56px;
    }
}