:root,
:root[data-theme="light"] {
    color-scheme: light;
    --color-bg: #f3efe8;
    --color-surface: rgba(255, 252, 247, 0.86);
    --color-surface-strong: #fffdf9;
    --color-border: rgba(60, 47, 33, 0.14);
    --color-border-strong: rgba(60, 47, 33, 0.22);
    --color-text: #1f1a15;
    --color-muted: #625648;
    --color-soft: #857867;
    --color-accent: #254c4a;
    --color-accent-soft: rgba(37, 76, 74, 0.1);
    --color-body-start: #f7f4ee;
    --color-body-end: #efe9de;
    --color-glow: rgba(37, 76, 74, 0.08);
    --color-grid-horizontal: rgba(255, 255, 255, 0.35);
    --color-grid-vertical: rgba(255, 255, 255, 0.28);
    --color-panel-sheen: rgba(255, 255, 255, 0.4);
    --color-input-bg: rgba(255, 255, 255, 0.88);
    --color-input-bg-focus: #ffffff;
    --color-focus-ring: rgba(37, 76, 74, 0.12);
    --color-button-text: #f7f4ee;
    --color-theme-toggle-bg: rgba(255, 255, 255, 0.72);
    --color-link-underline: rgba(37, 76, 74, 0.28);
    --color-button-shadow: rgba(37, 76, 74, 0.2);
    --color-loading-start: rgba(37, 76, 74, 0.08);
    --color-loading-end: rgba(255, 255, 255, 0.9);
    --color-error-border: rgba(146, 63, 52, 0.28);
    --color-bibtex-bg: #f4efe6;
    --color-bibtex-text: #2a221a;
    --shadow-soft: 0 18px 40px rgba(35, 29, 23, 0.08);
    --max-width: 1180px;
    --radius-lg: 28px;
    --radius-md: 18px;
    --radius-sm: 12px;
}

:root[data-theme="dark"] {
    color-scheme: dark;
    --color-bg: #17141f;
    --color-surface: rgba(31, 27, 40, 0.9);
    --color-surface-strong: #252330;
    --color-border: rgba(240, 236, 244, 0.08);
    --color-border-strong: rgba(192, 132, 200, 0.26);
    --color-text: #f0ecf4;
    --color-muted: #b8aec3;
    --color-soft: #8c8398;
    --color-accent: #c084c8;
    --color-accent-soft: rgba(192, 132, 200, 0.16);
    --color-body-start: #181520;
    --color-body-end: #0f0d14;
    --color-glow: rgba(104, 35, 109, 0.22);
    --color-grid-horizontal: rgba(255, 255, 255, 0.04);
    --color-grid-vertical: rgba(255, 255, 255, 0.03);
    --color-panel-sheen: rgba(255, 255, 255, 0.05);
    --color-input-bg: rgba(24, 21, 31, 0.96);
    --color-input-bg-focus: #1c1925;
    --color-focus-ring: rgba(212, 160, 218, 0.18);
    --color-button-text: #f6edf7;
    --color-theme-toggle-bg: rgba(255, 255, 255, 0.02);
    --color-link-underline: rgba(192, 132, 200, 0.3);
    --color-button-shadow: rgba(104, 35, 109, 0.32);
    --color-loading-start: rgba(192, 132, 200, 0.12);
    --color-loading-end: rgba(37, 35, 48, 0.92);
    --color-error-border: rgba(232, 99, 122, 0.32);
    --color-bibtex-bg: color-mix(in srgb, var(--color-body-end) 82%, black 18%);
    --color-bibtex-text: #f4f1eb;
    --shadow-soft: 0 26px 56px rgba(0, 0, 0, 0.34);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: "IBM Plex Sans", sans-serif;
    color: var(--color-text);
    background:
        radial-gradient(circle at top left, var(--color-glow), transparent 28%),
        radial-gradient(circle at 85% 15%, color-mix(in srgb, var(--color-accent) 18%, transparent), transparent 24%),
        linear-gradient(180deg, var(--color-body-start) 0%, var(--color-body-end) 100%);
    line-height: 1.6;
    transition: background-color 220ms ease, color 220ms ease;
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(var(--color-grid-horizontal) 1px, transparent 1px),
        linear-gradient(90deg, var(--color-grid-vertical) 1px, transparent 1px);
    background-size: 100% 100%, 32px 32px;
    opacity: 0.18;
    pointer-events: none;
}

a {
    color: inherit;
}

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

.page-shell {
    width: min(100% - 2rem, var(--max-width));
    margin: 0 auto;
    padding: 2rem 0 3rem;
}

.site-header {
    position: relative;
    padding: 2rem 0 2.5rem;
    border-bottom: 1px solid var(--color-border);
}

.header-mark {
    display: inline-flex;
    align-items: center;
    gap: 0.85rem;
    margin-bottom: 1.5rem;
}

.header-mark__line {
    width: 3rem;
    height: 1px;
    background: var(--color-border-strong);
}

.eyebrow,
.panel-kicker {
    font-size: 0.75rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-muted);
}

.site-header__body {
    display: grid;
    grid-template-columns: minmax(0, 2fr) minmax(220px, 0.8fr);
    gap: 2rem;
    align-items: end;
}

.site-header__copy {
    display: grid;
    gap: 1rem;
    max-width: 52rem;
}

.site-header h1,
.panel-heading h2,
.result-panel__header h3 {
    font-family: "Source Serif 4", serif;
    font-weight: 600;
    letter-spacing: -0.02em;
}

.site-header h1 {
    font-size: clamp(2.5rem, 5vw, 4.5rem);
    line-height: 0.98;
    max-width: 16ch;
}

.lede {
    max-width: 42rem;
    font-size: 1.15rem;
    color: var(--color-muted);
}

.site-header__actions {
    display: grid;
    gap: 0.95rem;
    justify-items: start;
}

.site-header__links {
    display: grid;
    gap: 0.8rem;
    justify-items: start;
}

.paper-link-group {
    display: inline-flex;
    align-items: center;
    gap: 0.55rem;
    flex-wrap: wrap;
}

.site-header__links a,
.inline-link {
    font-size: 0.95rem;
    color: var(--color-accent);
    text-decoration: none;
    border-bottom: 1px solid var(--color-link-underline);
    padding-bottom: 0.12rem;
    transition: border-color 180ms ease, color 180ms ease;
}

.site-header__links a:hover,
.inline-link:hover {
    border-color: var(--color-accent);
}

.oa-badge {
    border: 1px solid var(--color-border-strong);
    border-bottom-width: 1px;
    border-radius: 999px;
    padding: 0.18rem 0.55rem;
    background: var(--color-accent-soft);
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    line-height: 1;
}

.layout {
    display: grid;
    grid-template-columns: minmax(0, 1.2fr) minmax(320px, 0.8fr);
    gap: 2rem;
    padding-top: 2rem;
}

.content-column,
.calculator-column {
    display: grid;
    gap: 1.5rem;
    align-content: start;
}

.panel {
    position: relative;
    padding: 1.5rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-soft);
    backdrop-filter: blur(16px);
}

:root[data-theme="dark"] .panel {
    background:
        linear-gradient(180deg, color-mix(in srgb, var(--color-surface-strong) 76%, transparent) 0%, var(--color-surface) 100%);
}

.panel::after {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: inherit;
    border: 1px solid var(--color-panel-sheen);
    pointer-events: none;
}

.panel-heading {
    display: grid;
    gap: 0.4rem;
    margin-bottom: 1.2rem;
}

.panel-heading h2 {
    font-size: clamp(1.5rem, 2.4vw, 2.1rem);
    line-height: 1.08;
}

.panel-heading--compact {
    margin-bottom: 0.95rem;
}

.panel-heading--compact h3 {
    font-family: "Source Serif 4", serif;
    font-size: 1.45rem;
    line-height: 1.1;
    letter-spacing: -0.02em;
}

.panel-heading--split {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    gap: 1rem;
}

.reading-block {
    display: grid;
    gap: 1rem;
    max-width: 48rem;
    color: var(--color-muted);
}

.definition-grid,
.output-grid,
.result-grid {
    display: grid;
    gap: 1rem;
}

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

.definition-card,
.output-card,
.metric-card {
    padding: 1rem 1.1rem;
    border-radius: var(--radius-md);
    background: var(--color-surface-strong);
    border: 1px solid var(--color-border);
}

.definition-card__title,
.output-card__title,
.metric-card__label,
.field label {
    font-size: 0.92rem;
    font-weight: 600;
}

.definition-card__formula {
    margin-top: 0.55rem;
    font-size: 1.02rem;
}

.definition-card__text,
.output-card__text {
    margin-top: 0.7rem;
    color: var(--color-muted);
}

.output-card__text {
    max-width: 28ch;
}

.output-grid--rail {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0.85rem;
}

.output-grid--rail .output-card {
    min-height: 0;
}

.output-card--wide {
    grid-column: 1 / -1;
}

.panel--sticky {
    position: sticky;
    top: 1.5rem;
}

.calculator-form {
    display: grid;
    gap: 1.1rem;
}

.output-panel {
    margin-top: 1.35rem;
    padding-top: 1.35rem;
    border-top: 1px solid var(--color-border);
}

.field {
    display: grid;
    gap: 0.5rem;
}

.field-hint,
.result-note,
#result-status {
    color: var(--color-muted);
    font-size: 0.92rem;
}

input {
    width: 100%;
    padding: 0.95rem 1rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--color-border-strong);
    background: var(--color-input-bg);
    color: var(--color-text);
    font: inherit;
    transition: border-color 180ms ease, box-shadow 180ms ease, background-color 180ms ease;
}

input::placeholder {
    color: var(--color-soft);
}

input:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 4px var(--color-focus-ring);
    background: var(--color-input-bg-focus);
}

.calculator-form button {
    padding: 1rem 1.1rem;
    border: 0;
    border-radius: var(--radius-sm);
    background: var(--color-accent);
    color: var(--color-button-text);
    font: inherit;
    font-weight: 600;
    cursor: pointer;
    transition: transform 180ms ease, opacity 180ms ease, box-shadow 180ms ease;
    box-shadow: 0 14px 28px var(--color-button-shadow);
}

.calculator-form button:hover:not(:disabled) {
    transform: translateY(-1px);
}

.calculator-form button:disabled {
    opacity: 0.72;
    cursor: wait;
}

.theme-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    min-width: 11rem;
    padding: 0.7rem 0.95rem;
    border: 1px solid var(--color-border-strong);
    border-radius: 999px;
    background: var(--color-theme-toggle-bg);
    color: var(--color-text);
    font: inherit;
    cursor: pointer;
    transition:
        transform 180ms ease,
        background-color 180ms ease,
        border-color 180ms ease,
        color 180ms ease;
}

.theme-toggle:hover {
    transform: translateY(-1px);
    background: var(--color-accent-soft);
}

.theme-toggle__caption {
    font-size: 0.75rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--color-muted);
}

.theme-toggle__value {
    font-weight: 600;
}

.theme-toggle:focus-visible,
.calculator-form button:focus-visible,
input:focus-visible,
.site-header__links a:focus-visible,
.inline-link:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 3px;
}

.diagram-shell {
    padding: 0.8rem;
    border-radius: calc(var(--radius-lg) - 6px);
    border: 1px solid var(--color-border);
    background: var(--color-surface-strong);
}

.phase-diagram {
    display: block;
    width: 100%;
    height: auto;
    border-radius: calc(var(--radius-lg) - 10px);
}

.result-panel {
    margin-top: 1.4rem;
    padding-top: 1.4rem;
    border-top: 1px solid var(--color-border);
}

.result-panel__header {
    display: grid;
    gap: 0.35rem;
    margin-bottom: 1rem;
}

.result-panel__header h3 {
    font-size: 1.45rem;
    line-height: 1.1;
}

.result-grid {
    grid-template-columns: 1fr;
    gap: 0.75rem;
}

.metric-card {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    gap: 1rem;
    min-height: 0;
    padding-block: 0.9rem;
}

.metric-card__value {
    font-family: "Source Serif 4", serif;
    font-size: clamp(1.7rem, 3vw, 2.25rem);
    line-height: 1;
    text-align: right;
    white-space: nowrap;
}

.metric-card__label {
    color: var(--color-muted);
    max-width: 12ch;
}

.result-grid[data-state="loading"] .metric-card {
    background: linear-gradient(135deg, var(--color-loading-start), var(--color-loading-end));
}

.result-grid[data-state="error"] .metric-card {
    border-color: var(--color-error-border);
}

.result-note {
    margin-top: 0.9rem;
}

.video-frame {
    overflow: hidden;
    border-radius: calc(var(--radius-lg) - 8px);
    border: 1px solid var(--color-border);
    background: color-mix(in srgb, var(--color-body-end) 82%, black);
    aspect-ratio: 16 / 9;
}

.video-frame iframe {
    width: 100%;
    height: 100%;
    display: block;
}

.citation-banner {
    display: grid;
    gap: 1rem;
    margin-top: 2rem;
}

.citation-banner__header {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 1rem;
    align-items: end;
}

.citation-banner__links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.55rem;
    justify-content: flex-end;
}

.citation-chip {
    display: inline-flex;
    align-items: center;
    border: 1px solid var(--color-border-strong);
    border-radius: 999px;
    padding: 0.32rem 0.7rem;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    text-decoration: none;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.citation-banner__text {
    max-width: 70ch;
    color: var(--color-text);
    font-size: 1rem;
    line-height: 1.7;
}

.bibtex-card {
    border: 1px solid var(--color-border);
    border-radius: calc(var(--radius-lg) - 8px);
    background: var(--color-surface-strong);
    overflow: hidden;
}

.bibtex-card summary {
    list-style: none;
    cursor: pointer;
    padding: 0.95rem 1.05rem;
    font-weight: 600;
    color: var(--color-text);
    background: color-mix(in srgb, var(--color-surface-strong) 86%, var(--color-accent-soft) 14%);
}

.bibtex-card summary::-webkit-details-marker {
    display: none;
}

.bibtex-card__toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    padding: 0.85rem 1.05rem 0;
}

.bibtex-card__hint {
    color: var(--color-muted);
    font-size: 0.88rem;
}

.bibtex-copy {
    border: 1px solid var(--color-border-strong);
    border-radius: 999px;
    background: transparent;
    color: var(--color-accent);
    font: inherit;
    font-size: 0.84rem;
    font-weight: 600;
    padding: 0.4rem 0.8rem;
    cursor: pointer;
}

.bibtex-entry {
    margin: 0;
    padding: 1rem 1.05rem 1.1rem;
    overflow-x: auto;
    background: var(--color-bibtex-bg);
    color: var(--color-bibtex-text);
    border-top: 1px solid var(--color-border);
    font-family: "IBM Plex Sans", sans-serif;
    font-size: 0.92rem;
    line-height: 1.55;
}

.bibtex-entry code {
    font-family: "IBM Plex Mono", "SFMono-Regular", Consolas, monospace;
    white-space: pre;
}

.mjx-container {
    overflow-x: auto;
    overflow-y: hidden;
}

@keyframes reveal {
    from {
        opacity: 0;
        transform: translateY(1rem);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.site-header,
.panel {
    animation: reveal 560ms ease both;
}

.content-column .panel:nth-child(2) {
    animation-delay: 80ms;
}

.content-column .panel:nth-child(3) {
    animation-delay: 140ms;
}

.content-column .panel:nth-child(4) {
    animation-delay: 200ms;
}

.content-column .panel:nth-child(5) {
    animation-delay: 260ms;
}

.calculator-column .panel {
    animation-delay: 120ms;
}

@media (max-width: 980px) {
    .site-header__body,
    .layout,
    .definition-grid,
    .output-grid {
        grid-template-columns: 1fr;
    }

    .citation-banner__header {
        grid-template-columns: 1fr;
        align-items: start;
    }

    .citation-banner__links {
        justify-content: flex-start;
    }

    .output-card--wide {
        grid-column: auto;
    }

    .panel-heading--split {
        grid-template-columns: 1fr;
        align-items: start;
    }

    .site-header__actions {
        justify-items: start;
    }

    .panel--sticky {
        position: static;
    }
}

@media (max-width: 720px) {
    .page-shell {
        width: min(100% - 1rem, var(--max-width));
        padding: 1rem 0 2rem;
    }

    .site-header {
        padding-top: 1.25rem;
        padding-bottom: 2rem;
    }

    .panel {
        padding: 1.2rem;
        border-radius: 22px;
    }

    .site-header h1 {
        max-width: 12ch;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    .site-header,
    .panel,
    .calculator-form button,
    .theme-toggle,
    .bibtex-copy {
        animation: none;
        transition: none;
    }
}

/* ── Batch CSV upload ──────────────────────────────────────────────── */

.batch-form {
    display: flex;
    flex-direction: column;
    gap: 0;
    margin-top: 1.25rem;
}

.batch-form input[type="file"] {
    display: block;
    width: 100%;
    max-width: 420px;
    padding: 0.5rem 0.75rem;
    font-family: var(--font-mono, monospace);
    font-size: 0.85rem;
    background: var(--color-input-bg);
    color: var(--color-text);
    border: 1px solid var(--color-border-strong);
    border-radius: 8px;
    cursor: pointer;
    transition: border-color 0.18s;
}

.batch-form input[type="file"]:focus-visible {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px var(--color-focus-ring);
}

.batch-form input[type="file"]::file-selector-button {
    font-family: inherit;
    font-size: 0.82rem;
    padding: 0.25rem 0.65rem;
    background: var(--color-accent-soft);
    color: var(--color-accent);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    margin-right: 0.75rem;
    transition: background 0.18s;
}

.batch-form input[type="file"]::file-selector-button:hover {
    background: var(--color-accent);
    color: var(--color-button-text);
}

.batch-status-bar {
    margin-top: 1rem;
    font-size: 0.85rem;
    min-height: 1.4em;
    color: var(--color-muted);
}

.batch-status-bar[data-state="ok"]  { color: var(--color-accent); }
.batch-status-bar[data-state="err"] { color: #b84040; }

.batch-preview {
    margin-top: 1.5rem;
}

.batch-preview__kicker {
    margin-bottom: 0.5rem;
}

.batch-table-wrap {
    overflow-x: auto;
    border: 1px solid var(--color-border);
    border-radius: 10px;
}

.batch-table-wrap table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.82rem;
    font-family: var(--font-mono, monospace);
}

.batch-table-wrap th {
    background: var(--color-surface);
    color: var(--color-accent);
    text-align: left;
    padding: 0.45rem 0.85rem;
    border-bottom: 1px solid var(--color-border);
    font-weight: 500;
    white-space: nowrap;
}

.batch-table-wrap td {
    padding: 0.35rem 0.85rem;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text);
    white-space: nowrap;
}

.batch-table-wrap tr:last-child td {
    border-bottom: none;
}

.batch-table-wrap tr:hover td {
    background: var(--color-accent-soft);
}

.batch-table-wrap td.beta-col {
    color: var(--color-accent);
    font-weight: 500;
}

.batch-table-wrap td.error-val {
    color: #b84040;
}

.batch-table-wrap td.more-rows {
    color: var(--color-soft);
    font-style: italic;
}

.batch-download-btn {
    margin-top: 0.9rem;
    padding: 0.5rem 1.2rem;
    font-size: 0.88rem;
    background: transparent;
    color: var(--color-accent);
    border: 1px solid var(--color-accent);
    border-radius: 8px;
    cursor: pointer;
    font-family: var(--font-mono, monospace);
    transition: background 0.18s, color 0.18s;
}

.batch-download-btn:hover {
    background: var(--color-accent);
    color: var(--color-button-text);
}