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

:root {
    --accent: #1769aa;
    --text: #222;
    --muted: #666;
    --border: #e5e5e5;
    --soft-bg: #f7f8fa;
    --content-width: 1100px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.65;
    color: var(--text);
    background: #fff;
}

.skip-link {
    position: absolute;
    left: 16px;
    top: -80px;
    z-index: 100;
    padding: 10px 14px;
    border-radius: 4px;
    background: #111;
    color: #fff;
}

.skip-link:focus {
    top: 12px;
}

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

a:hover {
    text-decoration: underline;
}

a:focus-visible {
    outline: 3px solid #f0a500;
    outline-offset: 3px;
    border-radius: 2px;
}

header {
    border-bottom: 1px solid var(--border);
    background: #fff;
}

.nav {
    max-width: var(--content-width);
    margin: auto;
    padding: 18px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav nav {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: flex-end;
    gap: 10px 24px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    color: #111;
}

.logo span {
    color: var(--accent);
}

.nav nav a {
    font-size: 0.95rem;
    color: #444;
}

.nav nav a[aria-current="page"] {
    color: #111;
    font-weight: 700;
}

.hero {
    max-width: var(--content-width);
    margin: auto;
    padding: 90px 24px 75px;
}

.hero h1 {
    font-size: 3.2rem;
    line-height: 1.15;
    max-width: 800px;
    letter-spacing: -1.5px;
    margin-bottom: 22px;
}

.hero h1 span {
    color: var(--accent);
}

.hero p {
    max-width: 750px;
    font-size: 1.15rem;
    color: #555;
    margin-bottom: 30px;
}

.hero-proof {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 18px;
    margin-top: 28px;
    color: #555;
    font-size: 0.88rem;
}

.hero-proof span::before {
    content: "✓";
    margin-right: 6px;
    color: var(--accent);
    font-weight: 700;
}

a.button-primary,
a.button-secondary {
    display: inline-block;
    padding: 11px 20px;
    border: 1px solid var(--accent);
    border-radius: 5px;
    font-size: 0.95rem;
}

.buttons a {
    margin-right: 10px;
}

.button-primary {
    background: var(--accent);
    color: white;
}

.button-secondary {
    color: var(--accent);
}

section {
    max-width: var(--content-width);
    margin: auto;
    padding: 65px 24px;
}

.section-soft {
    max-width: none;
    padding-left: max(24px, calc((100% - var(--content-width)) / 2 + 24px));
    padding-right: max(24px, calc((100% - var(--content-width)) / 2 + 24px));
    background: var(--soft-bg);
}

section h2 {
    font-size: 1.8rem;
    margin-bottom: 12px;
    color: #111;
}

.section-intro {
    color: var(--muted);
    max-width: 760px;
    margin-bottom: 35px;
}

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

.feature-grid {
    grid-template-columns: repeat(2, 1fr);
}

.card {
    border: 1px solid #e4e4e4;
    border-radius: 7px;
    padding: 25px;
    background: #fff;
    display: flex;
    flex-direction: column;
}

.card h3 {
    font-size: 1.1rem;
    margin-bottom: 10px;
    color: #111;
}

.card p {
    color: var(--muted);
    font-size: 0.95rem;
}

.card > a {
    display: inline-block;
    margin-top: auto;
    padding-top: 15px;
    font-size: 0.9rem;
}

.evidence-tag {
    display: inline-flex;
    align-self: flex-start;
    margin-bottom: 13px;
    padding: 4px 9px;
    border: 1px solid #bdd6ea;
    border-radius: 999px;
    background: #f4f9fd;
    color: #285f89;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.01em;
}

.evidence-panel {
    max-width: var(--content-width);
    margin: 45px auto 70px;
    padding: 34px;
    border: 1px solid #bdd6ea;
    border-left: 5px solid var(--accent);
    border-radius: 8px;
    background: #f4f9fd;
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 35px;
}

.evidence-panel h2 {
    margin-bottom: 8px;
}

.evidence-panel p {
    max-width: 760px;
    color: #475b6b;
}

.evidence-panel > a {
    white-space: nowrap;
    border-color: #8ab8da;
}

.about {
    background: var(--soft-bg);
    max-width: none;
}

.about-content {
    max-width: var(--content-width);
    margin: auto;
    padding: 65px 24px;
}

.about-content p {
    max-width: 800px;
    color: #555;
}

.about-link {
    margin-top: 16px;
}

footer {
    border-top: 1px solid var(--border);
    padding: 30px 24px;
    text-align: center;
    color: var(--muted);
    font-size: 0.9rem;
}

/* Topic landing pages */
.topic-hero {
    padding-bottom: 35px;
}

.topic-label {
    color: var(--accent);
    font-weight: 700;
    font-size: 0.85rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 10px;
}

.about-grid {
    display: grid;
    grid-template-columns: minmax(0, 1.45fr) minmax(280px, 0.85fr);
    gap: 55px;
    align-items: start;
}

.about-grid p + p {
    margin-top: 18px;
}

.principles-card {
    padding: 25px;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--soft-bg);
}

.principles-card h2 {
    font-size: 1.25rem;
}

.principles-card ul {
    padding-left: 20px;
}

.principles-card li + li {
    margin-top: 8px;
}

.table-wrap {
    overflow-x: auto;
}

.evidence-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.94rem;
}

.evidence-table th,
.evidence-table td {
    padding: 13px 15px;
    border: 1px solid var(--border);
    text-align: left;
    vertical-align: top;
}

.evidence-table th {
    background: var(--soft-bg);
}

.numbered-principles {
    max-width: 850px;
    padding-left: 24px;
}

.numbered-principles li + li {
    margin-top: 12px;
}

.compact-buttons {
    margin-top: 25px;
}

/* Research article layout */
.article-shell {
    max-width: 1260px;
    margin: auto;
    display: grid;
    grid-template-columns: 250px minmax(0, 820px);
    gap: 55px;
    padding: 50px 24px 80px;
}

.article-sidebar {
    position: sticky;
    top: 24px;
    align-self: start;
    border-right: 1px solid var(--border);
    padding-right: 24px;
}

.article-sidebar h3 {
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 18px;
}

.sidebar-group {
    margin-bottom: 22px;
}

.sidebar-group strong {
    display: block;
    font-size: 0.82rem;
    color: #555;
    margin-bottom: 7px;
}

.sidebar-group a {
    display: block;
    padding: 5px 0;
    font-size: 0.92rem;
}

.sidebar-group a.active {
    font-weight: 700;
    color: #111;
}

.article-content {
    min-width: 0;
}

.breadcrumbs {
    font-size: 0.88rem;
    color: var(--muted);
    margin-bottom: 22px;
}

.article-content h1 {
    font-size: 2.6rem;
    line-height: 1.15;
    letter-spacing: -1px;
    margin-bottom: 14px;
}

.article-deck {
    color: #555;
    font-size: 1.08rem;
    margin-bottom: 22px;
}

.article-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px 16px;
    margin-bottom: 24px;
    color: #666;
    font-size: 0.84rem;
}

.article-meta .evidence-tag {
    margin-bottom: 0;
}

.article-meta > span:not(:last-child)::after {
    content: "·";
    margin-left: 16px;
    color: #aaa;
}

.article-meta > .evidence-tag::after {
    content: none;
}

.article-toc {
    margin: 26px 0;
    padding: 20px 22px;
    border: 1px solid var(--border);
    border-radius: 7px;
    background: var(--soft-bg);
}

.article-toc h2 {
    margin: 0 0 10px;
    font-size: 1rem;
}

.article-toc ol {
    columns: 2;
    column-gap: 36px;
    padding-left: 20px;
    font-size: 0.9rem;
}

.article-toc li {
    break-inside: avoid;
    margin-bottom: 5px;
}

.article-toc .toc-subitem {
    margin-left: 16px;
    font-size: 0.86rem;
}

.article-scope {
    margin: 24px 0 34px;
    padding: 14px 16px;
    border-left: 3px solid #8ab8da;
    background: #f8fbfd;
    color: #4f5f6b;
    font-size: 0.9rem;
}

.article-body h2 {
    font-size: 1.65rem;
    margin: 42px 0 14px;
}

.article-body h3 {
    font-size: 1.25rem;
    margin: 32px 0 10px;
}

.article-body p,
.article-body ul,
.article-body ol,
.article-body blockquote,
.article-body pre,
.article-body table {
    margin-bottom: 18px;
}

.article-body table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.94rem;
}

.atlas-page .article-shell {
    max-width: 1500px;
    grid-template-columns: 230px minmax(0, 1fr);
    gap: 42px;
}

.atlas-page .article-body table,
.radar-page .article-body table {
    display: block;
    max-width: 100%;
    overflow-x: auto;
}

.atlas-page .article-body th,
.atlas-page .article-body td {
    min-width: 165px;
}

.atlas-page .article-body th:first-child,
.atlas-page .article-body td:first-child {
    min-width: 145px;
}

.article-body th,
.article-body td {
    padding: 10px 12px;
    border: 1px solid var(--border);
    text-align: left;
    vertical-align: top;
}

.article-body th {
    background: var(--soft-bg);
}

.article-body code {
    overflow-wrap: anywhere;
}

.article-body ul,
.article-body ol {
    padding-left: 24px;
}

.article-body blockquote {
    border-left: 3px solid var(--accent);
    padding: 8px 0 8px 18px;
    color: #444;
}

.article-body .mermaid {
    margin: 26px 0;
    padding: 18px;
    overflow-x: auto;
    border: 1px solid var(--border);
    border-radius: 7px;
    background: #fff;
    text-align: center;
}

.article-body .technical-callout {
    margin: 24px 0;
    padding: 18px 20px;
    border: 1px solid #bdd6ea;
    border-left: 4px solid var(--accent);
    border-radius: 6px;
    background: #f4f9fd;
}

.article-body .technical-callout p:last-child {
    margin-bottom: 0;
}

.article-body .geometry-diagram {
    display: block;
    width: 100%;
    max-width: 760px;
    height: auto;
    margin: 24px auto;
    border: 1px solid var(--border);
    border-radius: 7px;
    background: #fbfcfe;
}

.article-body pre {
    overflow-x: auto;
    padding: 18px;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--soft-bg);
}

.article-nav {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
    margin-top: 55px;
    padding-top: 25px;
    border-top: 1px solid var(--border);
}

.article-nav a {
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 16px;
}

.article-nav .next {
    text-align: right;
}

@media (max-width: 800px) {
    .nav {
        flex-direction: column;
        gap: 12px;
    }

    .nav nav {
        justify-content: center;
        gap: 8px 16px;
    }

    .hero {
        padding-top: 60px;
    }

    .hero h1 {
        font-size: 2.3rem;
    }

    .grid {
        grid-template-columns: 1fr;
    }

    .feature-grid {
        grid-template-columns: 1fr;
    }

    .evidence-panel {
        margin-left: 18px;
        margin-right: 18px;
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .evidence-panel > a {
        white-space: normal;
    }

    .about-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .article-shell {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .atlas-page .article-shell {
        grid-template-columns: 1fr;
        gap: 30px;
    }

    .article-sidebar {
        position: static;
        border-right: 0;
        border-bottom: 1px solid var(--border);
        padding: 0 0 20px;
    }

    .article-content h1 {
        font-size: 2.1rem;
    }

    .article-meta > span::after {
        content: none !important;
    }

    .article-toc ol {
        columns: 1;
    }

    .article-body {
        overflow-x: auto;
    }
}