:root {
    color-scheme: dark;
    --bg: #080914;
    --panel: #111327;
    --panel-strong: #171a32;
    --text: #f4f7fb;
    --muted: #a5adbd;
    --line: rgba(255, 255, 255, 0.1);
    --cyan: #00ddff;
    --violet: #8b5cf6;
    --pink: #ec4899;
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    background:
        radial-gradient(circle at 20% 0%, rgba(0, 221, 255, 0.12), transparent 28rem),
        radial-gradient(circle at 90% 10%, rgba(236, 72, 153, 0.12), transparent 28rem),
        var(--bg);
    color: var(--text);
    font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

a {
    color: inherit;
}

.sp-header {
    position: sticky;
    top: 0;
    z-index: 20;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    min-height: 64px;
    padding: 0 28px;
    border-bottom: 1px solid var(--line);
    background: rgba(8, 9, 20, 0.86);
    backdrop-filter: blur(16px);
}

.sp-logo {
    color: var(--cyan);
    font-weight: 700;
    text-decoration: none;
    white-space: nowrap;
}

.sp-nav {
    display: flex;
    align-items: center;
    gap: 6px;
}

.sp-nav a,
.sp-menu summary {
    display: inline-flex;
    min-height: 36px;
    align-items: center;
    border-radius: 8px;
    padding: 0 12px;
    color: var(--muted);
    font-size: 0.92rem;
    text-decoration: none;
}

.sp-nav a:hover,
.sp-menu summary:hover {
    background: rgba(255, 255, 255, 0.07);
    color: var(--text);
}

.sp-menu {
    position: relative;
}

.sp-menu summary {
    cursor: pointer;
    list-style: none;
}

.sp-menu summary::-webkit-details-marker {
    display: none;
}

.sp-menu-panel {
    position: absolute;
    right: 0;
    top: calc(100% + 8px);
    display: grid;
    width: 230px;
    padding: 8px;
    border: 1px solid var(--line);
    border-radius: 10px;
    background: #111327;
    box-shadow: 0 18px 50px rgba(0, 0, 0, 0.34);
}

.sp-main {
    width: min(1160px, calc(100% - 32px));
    margin: 0 auto;
}

.sp-hero {
    min-height: calc(100vh - 64px);
    display: grid;
    align-content: center;
    gap: 24px;
    padding: 64px 0;
    text-align: center;
}

.sp-kicker {
    color: var(--cyan);
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.sp-hero h1,
.sp-page-head h1 {
    max-width: 900px;
    margin: 0 auto;
    font-size: clamp(2.4rem, 8vw, 5.8rem);
    line-height: 1;
}

.sp-hero p,
.sp-page-head p {
    max-width: 760px;
    margin: 0 auto;
    color: var(--muted);
    font-size: 1.08rem;
    line-height: 1.7;
}

.sp-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 12px;
}

.sp-button,
.icon-button {
    display: inline-flex;
    min-height: 42px;
    align-items: center;
    justify-content: center;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.05);
    color: var(--text);
    padding: 0 16px;
    font: inherit;
    text-decoration: none;
    cursor: pointer;
}

.sp-button.primary {
    border-color: rgba(0, 221, 255, 0.32);
    background: rgba(0, 221, 255, 0.14);
    color: var(--cyan);
}

.sp-grid-section,
.theory-layout,
.paper-list,
.sp-split,
.sp-band {
    margin: 34px 0 72px;
}

.sp-section-heading {
    margin-bottom: 22px;
}

.sp-section-heading span {
    color: var(--cyan);
    font-size: 0.76rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
}

.sp-section-heading h2,
.sp-split h2,
.sp-band h2 {
    margin: 8px 0 0;
    font-size: clamp(1.6rem, 4vw, 2.4rem);
}

.explorer-grid,
.theory-layout {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 16px;
}

.explorer-card,
.theory-panel,
.paper-card,
.sp-callout,
.sp-band {
    border: 1px solid var(--line);
    border-radius: 8px;
    background: linear-gradient(180deg, rgba(255, 255, 255, 0.055), rgba(255, 255, 255, 0.025));
}

.explorer-card {
    min-height: 230px;
    display: grid;
    align-content: end;
    padding: 20px;
    text-decoration: none;
    transition: transform 180ms ease, border-color 180ms ease;
}

.explorer-card:hover {
    border-color: color-mix(in srgb, var(--accent) 55%, white 10%);
    transform: translateY(-3px);
}

.card-symbol {
    color: var(--accent);
    font-size: 2.5rem;
    font-weight: 800;
}

.explorer-card h3,
.theory-panel h2,
.paper-card h2 {
    margin: 14px 0 8px;
}

.explorer-card p,
.theory-panel p,
.paper-card p,
.sp-split p,
.sp-band p {
    color: var(--muted);
    line-height: 1.65;
}

.explorer-card span,
.invariant-pill {
    width: fit-content;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.07);
    color: var(--muted);
    padding: 6px 10px;
    font-size: 0.8rem;
}

.sp-page-head {
    display: grid;
    gap: 18px;
    padding: 84px 0 34px;
    text-align: center;
}

.theory-panel,
.paper-card,
.sp-callout,
.sp-band {
    padding: 22px;
}

.sp-split {
    display: grid;
    grid-template-columns: 1.4fr 1fr;
    gap: 16px;
    align-items: start;
}

.paper-list {
    display: grid;
    gap: 16px;
}

.paper-card {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 18px;
}

.paper-missing {
    color: #fca5a5;
}

.explorer-shell {
    display: grid;
    grid-template-columns: minmax(280px, 380px) 1fr;
    gap: 18px;
    min-height: calc(100vh - 120px);
    padding: 28px 0;
}

.explorer-info,
.viewer-panel {
    border: 1px solid var(--line);
    border-radius: 8px;
    background: rgba(17, 19, 39, 0.76);
}

.explorer-info {
    display: grid;
    align-content: start;
    gap: 16px;
    padding: 22px;
}

.explorer-info h1 {
    margin: 0;
    font-size: clamp(2rem, 4vw, 3.4rem);
}

.explorer-info p {
    color: var(--muted);
    line-height: 1.65;
}

.back-link {
    color: var(--muted);
    font-size: 0.9rem;
    text-decoration: none;
}

.control-panel {
    display: grid;
    gap: 12px;
    margin-top: 8px;
}

.range-control,
.check-control {
    display: grid;
    gap: 8px;
    color: var(--muted);
    font-size: 0.9rem;
}

.range-control input {
    width: 100%;
    accent-color: var(--accent);
}

.check-control {
    grid-template-columns: auto 1fr;
    align-items: center;
}

.viewer-panel {
    position: relative;
    overflow: hidden;
    border: 0;
    border-radius: 0;
    background: transparent;
    min-height: 620px;
}

.topology-viewer {
    width: 100%;
    height: 100%;
    min-height: 620px;
}

.viewer-status {
    position: absolute;
    left: 14px;
    bottom: 14px;
    max-width: calc(100% - 28px);
    border: 1px solid var(--line);
    border-radius: 8px;
    background: rgba(8, 9, 20, 0.72);
    color: var(--muted);
    padding: 8px 10px;
    font-size: 0.86rem;
}

.sp-footer {
    display: flex;
    justify-content: center;
    gap: 14px;
    padding: 30px 16px;
    border-top: 1px solid var(--line);
    color: var(--muted);
    font-size: 0.9rem;
}

@media (max-width: 860px) {
    .sp-header,
    .sp-nav,
    .sp-footer {
        flex-wrap: wrap;
        justify-content: center;
    }

    .explorer-grid,
    .theory-layout,
    .sp-split,
    .explorer-shell {
        grid-template-columns: 1fr;
    }

    .paper-card {
        align-items: start;
        flex-direction: column;
    }

    .viewer-panel {
        order: -1;
    }

    .viewer-panel,
    .topology-viewer {
        min-height: 62vh;
    }
}