:root {
    --bg-dark: #102029;
    --bg-mid: #16313e;
    --surface: rgba(251, 249, 244, 0.92);
    --surface-strong: rgba(255, 255, 255, 0.98);
    --surface-soft: rgba(236, 242, 248, 0.9);
    --ink: #1b2a34;
    --muted: #667783;
    --line: rgba(27, 42, 52, 0.12);
    --accent: #1d77a4;
    --accent-strong: #0f577f;
    --accent-soft: #d6eef7;
    --copper: #d27a32;
    --copper-strong: #9b4f14;
    --success: #1f8f61;
    --danger: #c94757;
    --purple: #7c48d3;
    --shadow: 0 30px 72px rgba(10, 21, 28, 0.22);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    min-height: 100vh;
    color: var(--ink);
    font-family: "IBM Plex Sans JP", sans-serif;
    background:
        radial-gradient(circle at 12% 10%, rgba(210, 122, 50, 0.16), transparent 20%),
        radial-gradient(circle at 84% 14%, rgba(29, 119, 164, 0.2), transparent 20%),
        linear-gradient(180deg, #0a151d 0%, #16313e 18%, #efe7de 18.1%, #f7f2eb 100%);
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    pointer-events: none;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.024) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.024) 1px, transparent 1px),
        radial-gradient(circle at 18% 22%, rgba(255, 255, 255, 0.14) 0 1px, transparent 1.8px),
        radial-gradient(circle at 78% 14%, rgba(255, 255, 255, 0.1) 0 1px, transparent 1.8px);
    background-size: 48px 48px, 48px 48px, 320px 320px, 280px 280px;
    mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.84), rgba(0, 0, 0, 0.1));
}

a {
    color: inherit;
    text-decoration: none;
}

button,
input,
select {
    font: inherit;
}

canvas {
    display: block;
    width: 100%;
    height: 100%;
    touch-action: none;
}

.page-shell {
    width: min(1180px, calc(100% - 32px));
    margin: 0 auto;
    padding-bottom: 82px;
}

.site-header {
    position: sticky;
    top: 14px;
    z-index: 20;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
    margin: 18px 0 20px;
    padding: 16px 22px;
    border-radius: 999px;
    background: rgba(10, 21, 29, 0.82);
    border: 1px solid rgba(255, 255, 255, 0.11);
    backdrop-filter: blur(18px);
    box-shadow: 0 16px 38px rgba(0, 0, 0, 0.24);
}

.brand,
h1,
h2,
h3,
.signal-main,
.footer-title,
.formula-line {
    font-family: "Shippori Mincho", serif;
}

.brand {
    color: #f7efe1;
    font-size: 1.14rem;
    letter-spacing: 0.08em;
}

.site-nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-end;
    gap: 18px;
    color: rgba(247, 239, 225, 0.84);
    font-size: 0.95rem;
}

.site-nav a:hover,
.site-nav a:focus-visible,
.footer-links a:hover,
.footer-links a:focus-visible {
    color: white;
}

.section,
.signal-strip,
.site-footer {
    opacity: 0;
    transform: translateY(26px);
    transition: opacity 520ms ease, transform 520ms ease;
}

.reveal.is-visible,
.site-footer.is-visible {
    opacity: 1;
    transform: translateY(0);
}

.stage {
    display: grid;
    gap: 20px;
    padding: 34px 0 22px;
}

.stage-copy,
.control-panel,
.canvas-card,
.status-card,
.principle-card,
.formula-card,
.model-card,
.related-card,
.signal-strip,
.site-footer,
.metric-card,
.formula-box,
.legend-box {
    border: 1px solid rgba(255, 255, 255, 0.62);
    background: var(--surface);
    box-shadow: var(--shadow);
    backdrop-filter: blur(14px);
}

.stage-copy {
    padding: 30px 30px 26px;
    border-radius: 34px;
    position: relative;
    overflow: hidden;
}

.stage-copy::after {
    content: "";
    position: absolute;
    inset: auto -66px -118px auto;
    width: 310px;
    height: 310px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(210, 122, 50, 0.34), rgba(210, 122, 50, 0));
}

.eyebrow,
.card-label,
.signal-kicker {
    margin: 0 0 12px;
    color: var(--accent-strong);
    font-size: 0.84rem;
    font-weight: 700;
    letter-spacing: 0.2em;
    text-transform: uppercase;
}

h1,
h2,
h3,
.brand {
    line-height: 1.14;
}

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

h1 {
    margin-bottom: 0;
    font-size: clamp(2.7rem, 5vw, 4.6rem);
    letter-spacing: -0.04em;
}

h2 {
    margin-bottom: 0;
    font-size: clamp(1.86rem, 3.6vw, 2.92rem);
    letter-spacing: -0.03em;
}

h3 {
    margin-bottom: 10px;
    font-size: 1.28rem;
}

.stage-lead,
.panel-header p,
.section-heading p,
.principle-card p,
.formula-card p,
.model-card p,
.related-card p,
.signal-sub,
.site-footer p,
.status-card p,
.metric-card span,
.legend-list,
.formula-box p,
.control-group label,
.legend-box p,
.hint-box p {
    color: var(--muted);
}

.stage-lead {
    margin: 18px 0 0;
    max-width: 860px;
    font-size: 1.04rem;
    line-height: 1.84;
}

.stage-tags,
.footer-links,
.legend-list {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.stage-tags {
    margin-top: 22px;
    position: relative;
    z-index: 1;
}

.stage-tags span {
    padding: 10px 14px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.78);
    border: 1px solid rgba(16, 36, 59, 0.12);
    color: var(--accent-strong);
    font-weight: 600;
}

.playground-grid {
    order: -1;
    display: grid;
    grid-template-columns: 338px minmax(0, 1fr);
    gap: 18px;
    align-items: start;
}

.control-panel {
    padding: 22px 20px;
    border-radius: 32px;
    background: linear-gradient(180deg, rgba(255, 252, 248, 0.96), rgba(238, 244, 249, 0.92));
}

.panel-header h2 {
    font-size: 1.4rem;
}

.panel-header p {
    margin: 10px 0 0;
    line-height: 1.76;
}

.control-group + .control-group,
.formula-box,
.legend-box {
    margin-top: 18px;
}

.control-group {
    padding-top: 16px;
    border-top: 1px solid var(--line);
}

.control-group:first-of-type {
    padding-top: 0;
    border-top: 0;
}

.control-group h3 {
    margin-bottom: 12px;
    font-size: 1.08rem;
}

.control-group label {
    display: block;
    margin: 11px 0 6px;
    font-size: 0.95rem;
}

.range-value {
    font-weight: 700;
    color: var(--accent-strong);
}

input[type="range"] {
    width: 100%;
    accent-color: var(--accent);
}

select,
button {
    width: 100%;
    min-height: 46px;
    padding: 0 14px;
    border-radius: 14px;
    border: 1px solid rgba(26, 41, 52, 0.12);
    background: rgba(255, 255, 255, 0.94);
    color: var(--ink);
}

button {
    border: 0;
    cursor: pointer;
    font-weight: 700;
    color: #fffdf7;
    background: linear-gradient(135deg, var(--accent-strong), var(--accent));
    box-shadow: 0 14px 28px rgba(15, 87, 127, 0.22);
    transition: transform 180ms ease, box-shadow 180ms ease, opacity 180ms ease;
}

button:hover,
button:focus-visible {
    transform: translateY(-1px);
}

button.secondary {
    color: var(--ink);
    background: rgba(255, 255, 255, 0.94);
    border: 1px solid rgba(26, 41, 52, 0.12);
    box-shadow: none;
}

.button-grid {
    display: grid;
    gap: 10px;
    margin-top: 12px;
}

.dual-buttons {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.hint-box,
.formula-box,
.legend-box {
    padding: 16px 16px 14px;
    border-radius: 24px;
    background: rgba(255, 255, 255, 0.82);
}

.hint-box {
    border: 1px solid rgba(27, 42, 52, 0.08);
}

.hint-box p,
.formula-box p,
.legend-box p {
    margin-bottom: 8px;
}

.hint-box p:last-child,
.formula-box p:last-child,
.legend-box p:last-child {
    margin-bottom: 0;
}

.legend-list {
    gap: 8px 14px;
    font-size: 0.95rem;
}

.dot {
    display: inline-block;
    width: 11px;
    height: 11px;
    margin-right: 6px;
    border-radius: 50%;
    vertical-align: -1px;
}

.red { background: #ef4444; }
.blue { background: #2563eb; }
.green { background: #16a34a; }
.orange { background: #f97316; }
.purple { background: #9333ea; }

.display-column {
    display: grid;
    gap: 16px;
}

.canvas-card {
    padding: 16px;
    border-radius: 34px;
    background: linear-gradient(180deg, rgba(246, 249, 255, 0.96), rgba(229, 237, 247, 0.94));
}

.canvas-stage {
    height: clamp(430px, 58vh, 720px);
    border-radius: 28px;
    overflow: hidden;
    border: 1px solid rgba(255, 255, 255, 0.18);
    box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.08), 0 22px 46px rgba(4, 11, 20, 0.22);
    background: linear-gradient(180deg, #eaf0f8 0%, #d9e4f0 100%);
}

#eddyCurrentCanvas {
    width: 100%;
    height: 100%;
}

.metric-grid,
.status-grid,
.principle-grid,
.formula-strip,
.model-grid,
.related-grid {
    display: grid;
    gap: 14px;
}

.metric-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    margin-top: 14px;
}

.metric-card {
    padding: 16px 14px;
    border-radius: 22px;
    background: rgba(255, 255, 255, 0.82);
}

.metric-card span {
    display: block;
    font-size: 0.88rem;
    margin-bottom: 8px;
}

.metric-card strong {
    display: block;
    font-size: 1.04rem;
    color: var(--ink);
    line-height: 1.4;
}

.status-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
}

.status-card,
.principle-card,
.formula-card,
.model-card,
.related-card {
    padding: 22px 20px;
    border-radius: 30px;
}

.status-card h2 {
    font-size: 1.4rem;
}

.signal-strip {
    margin: 14px 0 30px;
    padding: 22px 28px;
    border-radius: 30px;
    text-align: center;
}

.signal-main {
    margin: 0;
    font-size: clamp(1.34rem, 2.6vw, 1.9rem);
}

.signal-sub {
    margin: 10px auto 0;
    max-width: 760px;
    line-height: 1.8;
}

.section + .section {
    margin-top: 20px;
}

.section-heading {
    max-width: 820px;
    margin-bottom: 20px;
}

.section-heading p {
    margin-bottom: 0;
    line-height: 1.8;
}

.principle-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
}

.formula-strip {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    margin-top: 16px;
}

.model-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
}

.related-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
}

.formula-line {
    font-size: 1.06rem;
    color: var(--ink);
    line-height: 1.6;
}

.formula-line span {
    font-family: "IBM Plex Sans JP", sans-serif;
    font-weight: 600;
}

.strong-card,
.feature-card {
    background: linear-gradient(180deg, rgba(219, 241, 249, 0.94), rgba(255, 255, 255, 0.95));
}

.warm-card {
    background: linear-gradient(180deg, rgba(250, 238, 217, 0.94), rgba(255, 255, 255, 0.96));
}

.night-card {
    background: linear-gradient(180deg, rgba(231, 237, 246, 0.94), rgba(255, 255, 255, 0.96));
}

.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 48px;
    padding: 0 20px;
    border-radius: 999px;
    font-weight: 700;
    transition: transform 180ms ease, box-shadow 180ms ease;
}

.button:hover,
.button:focus-visible {
    transform: translateY(-1px);
}

.button-primary {
    color: #fffdf7;
    background: linear-gradient(135deg, var(--accent-strong), var(--accent));
    box-shadow: 0 16px 32px rgba(15, 87, 127, 0.22);
}

.button-secondary {
    color: var(--ink);
    background: rgba(255, 255, 255, 0.92);
    border: 1px solid rgba(26, 41, 52, 0.12);
}

.related-card {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.related-card .button {
    margin-top: auto;
}

.site-footer {
    margin-top: 42px;
    padding: 28px 30px;
    border-radius: 32px;
    background: rgba(10, 21, 29, 0.92);
    border: 1px solid rgba(255, 255, 255, 0.12);
    box-shadow: 0 20px 48px rgba(8, 16, 24, 0.28);
}

.footer-title {
    margin-bottom: 8px;
    color: #f8f0e6;
    font-size: 1.16rem;
}

.site-footer p {
    color: rgba(239, 245, 251, 0.86);
}

.footer-links {
    margin-top: 16px;
    color: rgba(239, 245, 251, 0.82);
}

@media (max-width: 1180px) {
    .principle-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .related-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 1080px) {
    .playground-grid {
        grid-template-columns: 1fr;
    }

    .metric-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }

    .status-grid,
    .model-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 860px) {
    .page-shell {
        width: min(100%, calc(100% - 22px));
    }

    .site-header {
        align-items: flex-start;
        border-radius: 30px;
        padding: 16px 18px;
    }

    .site-nav {
        justify-content: flex-start;
        gap: 12px 16px;
    }

    .formula-strip,
    .model-grid,
    .related-grid {
        grid-template-columns: 1fr;
    }

    .canvas-card,
    .stage-copy,
    .control-panel,
    .status-card,
    .principle-card,
    .formula-card,
    .model-card,
    .related-card,
    .signal-strip {
        border-radius: 26px;
    }
}

@media (max-width: 680px) {
    .page-shell {
        width: min(100%, calc(100% - 18px));
    }

    .stage-copy,
    .control-panel,
    .canvas-card,
    .status-card,
    .principle-card,
    .formula-card,
    .model-card,
    .related-card,
    .signal-strip,
    .site-footer,
    .metric-card,
    .formula-box,
    .legend-box,
    .hint-box {
        padding-left: 16px;
        padding-right: 16px;
    }

    .metric-grid,
    .status-grid,
    .principle-grid,
    .dual-buttons {
        grid-template-columns: 1fr;
    }

    .canvas-stage {
        height: 420px;
    }

    .button,
    .button-grid button {
        width: 100%;
    }

    .footer-links {
        flex-direction: column;
        gap: 10px;
    }
}