:root {
    color-scheme: dark;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    --panel-bg: rgba(22, 25, 34, 0.82);
    --panel-border: rgba(255, 255, 255, 0.08);
    --text: rgba(255, 255, 255, 0.9);
    --text-dim: rgba(255, 255, 255, 0.62);
    --accent: #7fe0ff;
    --arc-a: #7fe0ff;
    --arc-b: #ffa94d;
    --arc-free: rgba(255, 255, 255, 0.25);
    --body1: #ff5f6d;
    --body2: #ffd166;
    --body3: #5ee7df;
}

* {
    box-sizing: border-box;
}

html,
body {
    margin: 0;
    height: 100%;
    overflow: hidden;
    background: radial-gradient(circle at top, #262640, #0e0e15 62%);
    color: var(--text);
}

/* ---------- layout ---------- */
#layout {
    display: flex;
    height: 100%;
    width: 100%;
}

#views {
    flex: 1;
    min-width: 0;
    display: grid;
    grid-template-columns: 1.25fr 1fr;
    grid-template-rows: 1fr 1fr;
    gap: 10px;
    padding: 10px;
    padding-top: 58px;
}

.view {
    position: relative;
    min-width: 0;
    min-height: 0;
    border-radius: 14px;
    border: 1px solid var(--panel-border);
    background: rgba(12, 14, 20, 0.55);
    overflow: hidden;
}

#view-real {
    grid-row: 1 / 3;
}

.view canvas,
.view #sphereHost {
    display: block;
    width: 100%;
    height: 100%;
}

.view-label {
    position: absolute;
    top: 8px;
    left: 12px;
    z-index: 3;
    font-size: 0.72rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--text-dim);
    pointer-events: none;
}

.view-label .hint {
    text-transform: none;
    letter-spacing: 0;
    opacity: 0.6;
    margin-left: 6px;
}

/* ---------- back link ---------- */
.back-link {
    position: fixed;
    top: 14px;
    left: 14px;
    z-index: 20;
    padding: 7px 13px;
    border-radius: 999px;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    color: var(--text-dim);
    text-decoration: none;
    font-size: 0.82rem;
    backdrop-filter: blur(10px);
    transition: color 140ms ease, border-color 140ms ease;
}

.back-link:hover {
    color: var(--text);
    border-color: rgba(255, 255, 255, 0.25);
}

/* ---------- UI panel ---------- */
#ui-container {
    flex: 0 0 312px;
    max-height: calc(100% - 20px);
    overflow-y: auto;
    padding: 16px;
    margin: 10px 10px 10px 0;
    border-radius: 16px;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(12px);
    display: flex;
    flex-direction: column;
    gap: 13px;
}

body.ui-collapsed #ui-container {
    display: none;
}

#ui-toggle {
    position: fixed;
    top: 14px;
    right: 14px;
    z-index: 21;
    display: none;
}

body.ui-collapsed #ui-toggle {
    display: block;
}

.ui-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
}

.ui-header h1 {
    margin: 0;
    font-size: 1.1rem;
    letter-spacing: 0.03em;
}

.header-controls {
    display: flex;
    gap: 6px;
}

.subtitle {
    font-size: 0.78rem;
    line-height: 1.5;
    color: var(--text-dim);
}

.subtitle a,
.modal-content a {
    color: var(--accent);
}

/* ---------- controls ---------- */
.control-group {
    display: flex;
    flex-direction: column;
    gap: 7px;
}

.control-group>label {
    font-size: 0.78rem;
    color: var(--text-dim);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 8px;
}

.value-badge {
    font-variant-numeric: tabular-nums;
    font-size: 0.72rem;
    padding: 1px 7px;
    border-radius: 999px;
    background: rgba(255, 255, 255, 0.07);
    color: var(--text);
}

select {
    width: 100%;
    padding: 8px 10px;
    border-radius: 9px;
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--panel-border);
    color: var(--text);
    font-size: 0.85rem;
    font-family: inherit;
}

select optgroup {
    background: #171a22;
}

.orbit-meta {
    font-size: 0.74rem;
    line-height: 1.45;
    color: var(--text-dim);
}

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

button {
    font-family: inherit;
    font-size: 0.82rem;
    padding: 8px 12px;
    border-radius: 9px;
    background: rgba(255, 255, 255, 0.06);
    border: 1px solid var(--panel-border);
    color: var(--text);
    cursor: pointer;
    transition: background 140ms ease, border-color 140ms ease;
}

button:hover {
    background: rgba(255, 255, 255, 0.12);
    border-color: rgba(255, 255, 255, 0.24);
}

.accent-btn {
    background: rgba(127, 224, 255, 0.14);
    border-color: rgba(127, 224, 255, 0.35);
    color: #d8f6ff;
}

.accent-btn:hover {
    background: rgba(127, 224, 255, 0.24);
}

.btn-row {
    display: flex;
    gap: 8px;
}

.btn-row button {
    flex: 1;
}

.icon-btn {
    width: 38px;
    height: 38px;
    padding: 0;
    border-radius: 999px;
    background: var(--panel-bg);
    border: 1px solid var(--panel-border);
    backdrop-filter: blur(10px);
    font-size: 1rem;
}

.icon-btn.small {
    width: 26px;
    height: 26px;
    font-size: 0.8rem;
    backdrop-filter: none;
}

.checks {
    gap: 5px;
}

.check {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.78rem;
    color: var(--text-dim);
    cursor: pointer;
}

.check input {
    accent-color: var(--accent);
}

/* ---------- word ---------- */
.word-box {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 0.92rem;
    line-height: 1.8;
    letter-spacing: 0.04em;
    word-break: break-all;
    padding: 9px 10px;
    border-radius: 9px;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--panel-border);
    min-height: 40px;
}

.word-box .ltr {
    transition: none;
    padding: 0 0.5px;
    border-radius: 3px;
}

.word-box .ltr.a {
    color: var(--arc-a);
}

.word-box .ltr.b {
    color: var(--arc-b);
}

.word-box .ltr.now {
    background: rgba(255, 255, 255, 0.92);
    color: #0e0e15;
    font-weight: 700;
}

.word-legend {
    display: flex;
    flex-direction: column;
    gap: 3px;
    font-size: 0.7rem;
    color: var(--text-dim);
}

.word-legend i {
    display: inline-block;
    width: 18px;
    height: 3px;
    border-radius: 2px;
    vertical-align: middle;
    margin-right: 6px;
}

.sw.a {
    background: var(--arc-a);
}

.sw.b {
    background: var(--arc-b);
}

.sw.free {
    background: var(--arc-free);
}

/* ---------- stats ---------- */
.stats {
    display: flex;
    flex-direction: column;
    gap: 4px;
    padding-top: 10px;
    border-top: 1px solid var(--panel-border);
    font-size: 0.75rem;
    color: var(--text-dim);
}

.stat-row {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 10px;
}

.stat-value {
    color: var(--text);
    font-variant-numeric: tabular-nums;
    text-align: right;
    word-break: break-all;
}

.stat-value.mono {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 0.7rem;
}

.ok {
    color: #7bd88f;
}

.bad {
    color: #ff7b72;
}

/* ---------- modal ---------- */
.modal {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 40;
    background: rgba(0, 0, 0, 0.65);
    backdrop-filter: blur(4px);
    overflow-y: auto;
}

.modal.open {
    display: block;
}

.modal-content {
    position: relative;
    margin: 6vh auto;
    max-width: 720px;
    padding: 30px 36px 40px;
    border-radius: 16px;
    background: #171a22;
    border: 1px solid var(--panel-border);
    line-height: 1.65;
    font-size: 0.9rem;
}

.modal-content h2 {
    margin-top: 0;
}

.modal-content h3 {
    margin-top: 1.8rem;
    color: var(--accent);
    font-size: 1rem;
}

.modal-content code {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    background: rgba(255, 255, 255, 0.08);
    padding: 1px 5px;
    border-radius: 4px;
}

.modal-content .eq {
    text-align: center;
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 0.86rem;
    color: var(--accent);
    background: rgba(0, 0, 0, 0.3);
    padding: 12px;
    border-radius: 9px;
}

.close-modal {
    position: absolute;
    top: 14px;
    right: 20px;
    font-size: 1.7rem;
    line-height: 1;
    color: var(--text-dim);
    cursor: pointer;
}

.close-modal:hover {
    color: var(--text);
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
    html, body {
        overflow: auto;
    }

    #layout {
        flex-direction: column;
        height: auto;
    }

    #views {
        grid-template-columns: 1fr;
        grid-template-rows: 78vw 78vw 78vw;
        padding-top: 60px;
    }

    #view-real {
        grid-row: auto;
    }

    #ui-container {
        flex: none;
        margin: 0 10px 10px;
        max-height: none;
    }

    body.ui-collapsed #ui-container {
        display: flex;
    }

    #ui-toggle {
        display: none !important;
    }

    .modal-content {
        margin: 3vh 10px;
        padding: 26px 20px 32px;
    }
}

.warn {
    color: #ffc978;
}

.warn-note {
    display: block;
    margin-top: 6px;
    padding: 7px 9px;
    border-radius: 8px;
    background: rgba(255, 169, 77, 0.1);
    border: 1px solid rgba(255, 169, 77, 0.25);
    color: #ffd7a8;
    font-size: 0.72rem;
    line-height: 1.45;
}

/* ---------- reduction chain ---------- */
.reduce-box {
    display: flex;
    flex-direction: column;
    gap: 5px;
    padding: 9px 10px;
    border-radius: 9px;
    background: rgba(0, 0, 0, 0.3);
    border: 1px solid var(--panel-border);
}

.reduce-row {
    display: grid;
    grid-template-columns: 78px 1fr;
    gap: 8px;
    align-items: baseline;
    font-size: 0.7rem;
}

.reduce-row > span {
    color: var(--text-dim);
}

.reduce-row > code {
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 0.72rem;
    line-height: 1.45;
    word-break: break-all;
    color: var(--text);
}

.reduce-row.final {
    margin-top: 3px;
    padding-top: 6px;
    border-top: 1px solid var(--panel-border);
}

.reduce-row.final > span {
    color: var(--accent);
}

.reduce-row.final > code {
    color: var(--accent);
    font-weight: 600;
}

.reduce-row .same {
    color: var(--text-dim);
    opacity: 0.55;
}