:root {
    color-scheme: dark;
    --bg: #22262e;
    --bg-raise: #282d37;
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(255, 255, 255, 0.10);
    --card-border-hover: rgba(255, 255, 255, 0.20);
    --ink: #f2f3f5;
    --muted: #a6acb9;
    --faint: #7a8090;
    --accent: #34d399;
    --accent-strong: #6ee7b7;
    --accent-soft: rgba(52, 211, 153, 0.14);
    --accent-glow: rgba(52, 211, 153, 0.25);
    --gold: #fbbf24;
    --danger: #f87171;
    --shadow: 0 1px 0 rgba(255, 255, 255, 0.05) inset, 0 14px 36px rgba(0, 0, 0, 0.35);
    --serif: "Noto Serif TC", "Iwanami Mincho", "Songti TC", serif;
    --sans: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;

    /* Fluent UI dark tokens */
    --neutral-layer-1: #282d37;
    --neutral-layer-2: #2e3440;
    --neutral-layer-3: #353c49;
    --neutral-layer-4: #3d4452;
    --neutral-fill-layer-rest: #282d37;
    --fill-color: #282d37;
    --neutral-foreground-rest: #f2f3f5;
    --neutral-foreground-hover: #ffffff;
    --neutral-foreground-active: #f2f3f5;
    --neutral-foreground-hint: #a6acb9;
    --neutral-stroke-rest: rgba(255, 255, 255, 0.12);
    --neutral-stroke-hover: rgba(255, 255, 255, 0.22);
    --neutral-stroke-active: rgba(255, 255, 255, 0.28);
    --neutral-fill-input-rest: #1d212a;
    --neutral-fill-input-hover: #232834;
    --neutral-fill-input-focus: #1d212a;
    --neutral-fill-stealth-rest: transparent;
    --neutral-fill-stealth-hover: rgba(255, 255, 255, 0.07);
    --neutral-fill-stealth-active: rgba(255, 255, 255, 0.11);
    --neutral-fill-secondary-rest: rgba(255, 255, 255, 0.09);
    --neutral-fill-secondary-hover: rgba(255, 255, 255, 0.13);
}

html,
body {
    min-height: 100%;
    max-width: 100%;
    margin: 0;
    overflow-x: hidden;
    background:
        radial-gradient(1000px 480px at 12% -8%, rgba(52, 211, 153, 0.10), transparent 55%),
        radial-gradient(860px 420px at 108% -4%, rgba(251, 191, 36, 0.06), transparent 50%),
        radial-gradient(760px 620px at 50% 125%, rgba(52, 211, 153, 0.06), transparent 60%),
        linear-gradient(180deg, #282d38 0%, var(--bg) 45%);
    color: var(--ink);
    font-family: var(--sans);
    font-size: 16px;
    line-height: 1.6;
}

body::before {
    content: "";
    position: fixed;
    inset: 0;
    pointer-events: none;
    opacity: 0.10;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.35'/%3E%3C/svg%3E");
    z-index: 0;
}

::selection {
    background: rgba(52, 211, 153, 0.30);
    color: #ffffff;
}

::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: #3a4150;
    border-radius: 8px;
    border: 2px solid var(--bg);
}

::-webkit-scrollbar-thumb:hover {
    background: #4a5265;
}

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
    border-radius: 4px;
}

#components-reconnect-modal {
    z-index: 10000;
}

.page-body {
    position: relative;
    z-index: 1;
    padding: 2.25rem 1.25rem calc(4rem + env(safe-area-inset-bottom, 0px));
    max-width: 1080px;
    width: 100%;
    margin: 0 auto;
    box-sizing: border-box;
    overflow-x: visible !important;
    height: auto !important;
}

.page-body:has(.auth-shell) {
    max-width: none;
    padding: 0;
}

.page {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    min-width: 0;
    max-width: 100%;
}

.page-head {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
    margin-bottom: 0.25rem;
}

.page-head-row {
    display: flex;
    align-items: flex-end;
    justify-content: space-between;
    gap: 1rem;
    flex-wrap: wrap;
}

.kicker {
    margin: 0;
    color: var(--accent);
    font-size: 0.76rem;
    font-weight: 600;
    letter-spacing: 0.18em;
    text-transform: uppercase;
}

h1,
.page-title,
fluent-label[typo="pagetitle"] {
    margin: 0;
    font-family: var(--serif);
    font-size: clamp(1.8rem, 3vw, 2.35rem);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.01em;
    color: var(--ink);
}

h2,
.section-title,
fluent-label[typo="header"] {
    margin: 0 0 0.4rem;
    font-family: var(--serif);
    font-size: 1.18rem;
    font-weight: 700;
    color: var(--ink);
}

h2 > svg {
    vertical-align: -0.18em;
    margin-right: 0.45rem;
}

.lede,
fluent-label[typo="body"] {
    color: var(--muted);
}

.lede {
    margin: 0;
    max-width: 40rem;
}

a {
    color: var(--accent);
}

.back-link {
    width: fit-content;
    color: var(--muted) !important;
    font-size: 0.92rem;
    transition: color 0.15s ease;
}

.back-link:hover {
    color: var(--accent-strong) !important;
}

/* ---------- message bars ---------- */

/* Fluent's static SSR markup initially uses its light message-bar surfaces.
   Pin both sides of the contrast pair so the dark application tokens cannot
   produce light text on a light background before interactivity starts. */
.fluent-messagebar {
    --neutral-foreground-rest: #f8fafc;
    --neutral-fill-strong-active: #f8fafc;
    color: #f8fafc !important;
    opacity: 1 !important;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.22);
}

.fluent-messagebar[animation="fadein"] {
    animation: none !important;
}

.fluent-messagebar.intent-info,
.fluent-messagebar.intent-custom {
    background-color: #273244 !important;
    border-color: #64748b !important;
}

.fluent-messagebar.intent-success {
    background-color: #052e16 !important;
    border-color: #34d399 !important;
}

.fluent-messagebar.intent-warning {
    background-color: #422006 !important;
    border-color: #fbbf24 !important;
}

.fluent-messagebar.intent-error {
    background-color: #450a0a !important;
    border-color: #f87171 !important;
}

.fluent-messagebar.intent-info .fluent-messagebar-icon,
.fluent-messagebar.intent-custom .fluent-messagebar-icon {
    color: #cbd5e1;
}

.fluent-messagebar.intent-success .fluent-messagebar-icon {
    color: #6ee7b7;
}

.fluent-messagebar.intent-warning .fluent-messagebar-icon {
    color: #fcd34d;
}

.fluent-messagebar.intent-error .fluent-messagebar-icon {
    color: #fca5a5;
}

.fluent-messagebar .fluent-messagebar-icon svg,
.fluent-messagebar .fluent-messagebar-close {
    fill: currentColor !important;
}

.fluent-messagebar fluent-anchor,
.fluent-messagebar a {
    color: #a7f3d0 !important;
}

/* ---------- header / nav ---------- */

header.site-header,
fluent-header.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(34, 38, 46, 0.78) !important;
    backdrop-filter: blur(14px) saturate(1.5);
    -webkit-backdrop-filter: blur(14px) saturate(1.5);
    color: var(--ink) !important;
    min-height: 64px;
    height: 64px !important;
    padding: 0 1.5rem !important;
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    --fill-color: rgba(34, 38, 46, 0.78);
    --neutral-fill-rest: transparent;
    --neutral-foreground-rest: var(--ink);
    --accent-foreground-rest: var(--ink);
    --neutral-fill-stealth-rest: transparent;
    --neutral-fill-stealth-hover: rgba(255, 255, 255, 0.07);
}

.brand {
    display: inline-flex;
    align-items: center;
    gap: 0.55rem;
    font-family: var(--serif);
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--ink) !important;
    text-decoration: none;
    letter-spacing: 0.05em;
}

.brand svg {
    fill: var(--accent) !important;
    filter: drop-shadow(0 0 10px var(--accent-glow));
}

.nav {
    display: flex;
    align-items: center;
    gap: 0.35rem;
}

.nav-logout {
    display: contents;
}

.nav fluent-anchor,
.nav-user {
    color: #d4d4d8 !important;
    font-size: 0.92rem;
}

.nav-user {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0 0.6rem;
    color: var(--muted) !important;
}

.nav-user svg {
    fill: var(--faint) !important;
}

/* ---------- cards ---------- */

fluent-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    box-shadow: var(--shadow);
    padding: 1.25rem 1.35rem;
    margin: 0;
    max-width: 100%;
    min-width: 0;
    overflow: visible;
    box-sizing: border-box;
    backdrop-filter: blur(6px);
    transition: border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 1rem;
}

.course-card {
    display: flex;
    flex-direction: column;
    min-height: 220px;
    height: 100%;
}

.course-card:hover {
    transform: translateY(-3px);
    border-color: var(--card-border-hover);
    box-shadow: 0 1px 0 rgba(255, 255, 255, 0.05) inset, 0 22px 48px rgba(0, 0, 0, 0.55);
}

.course-card p {
    margin: 0.35rem 0 0.7rem;
    color: var(--muted);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
    flex: 1;
}

.course-meta {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.35rem 0.9rem;
    font-size: 0.86rem;
    color: var(--muted);
    margin-bottom: 0.7rem;
}

.course-meta span {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
}

.course-meta svg {
    fill: var(--faint) !important;
}

.course-card-foot {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    margin-top: auto;
    padding-top: 0.85rem;
    border-top: 1px solid var(--card-border);
}

.lesson-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
}

.lesson-row-main {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.badge-row {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
}

.badge-row fluent-badge {
    display: inline-flex;
    align-items: center;
}

.badge-row fluent-badge svg {
    fill: currentColor !important;
    margin-right: 0.25rem;
    vertical-align: -0.15em;
}

/* ---------- player ---------- */

.player-wrap {
    overflow: hidden;
    padding: 0.6rem;
    background: #000000;
    border-color: rgba(255, 255, 255, 0.10);
    box-shadow: 0 0 0 1px rgba(52, 211, 153, 0.06), 0 24px 60px rgba(0, 0, 0, 0.6);
}

.player-frame {
    width: 100%;
    aspect-ratio: 16 / 9;
    border: 0;
    background: #000;
    border-radius: 10px;
    display: block;
}

/* ---------- auth ---------- */

.auth-shell {
    min-height: calc(100vh - 64px);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    padding: 2rem 1rem 4rem;
}

.brand-mark {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    margin: 0;
    font-family: var(--serif);
    font-size: 2rem;
    color: var(--ink);
}

.brand-mark fluent-icon {
    color: var(--accent);
    filter: drop-shadow(0 0 14px var(--accent-glow));
}

.auth-card {
    width: min(420px, 100%);
    box-shadow: 0 0 90px rgba(52, 211, 153, 0.07), var(--shadow);
}

.auth-card .lede,
.auth-card fluent-label[typo="body"] {
    display: block;
    margin: 0.35rem 0 1rem;
}

.auth-card fluent-stack,
.form-stack {
    display: flex;
    flex-direction: column;
    gap: 0.85rem;
    min-width: 0;
    max-width: 100%;
}

.field-label {
    display: block;
    font-size: 0.85rem;
    color: var(--muted);
}

.field {
    display: block;
    width: 100%;
    max-width: 100%;
    min-width: 0;
    box-sizing: border-box;
    min-height: 8.5rem;
    padding: 0.75rem 0.85rem;
    border: 1px solid var(--neutral-stroke-rest);
    border-radius: 10px;
    background: var(--neutral-fill-input-rest);
    color: var(--ink);
    font-family: inherit;
    font-size: 16px;
    line-height: 1.55;
    resize: vertical;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.field:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(52, 211, 153, 0.16);
}

.field-sm {
    min-height: 6.5rem;
}

.auth-card fluent-button,
.form-stack fluent-button {
    margin-top: 0.35rem;
}

.auth-follow {
    display: inline-block;
    margin-top: 1rem;
}

/* ---------- buttons ---------- */

fluent-button[appearance="accent"],
fluent-anchor[appearance="accent"] {
    filter: drop-shadow(0 4px 16px rgba(52, 211, 153, 0.18));
}

fluent-button svg,
fluent-anchor svg {
    fill: currentColor !important;
}

/* ---------- empty states ---------- */

.empty {
    background: var(--card-bg);
    border: 1px dashed rgba(255, 255, 255, 0.14);
    border-radius: 16px;
    padding: 2.6rem 1.5rem;
    text-align: center;
}

.empty-icon {
    fill: var(--faint) !important;
    margin-bottom: 0.6rem;
}

.empty-title {
    margin: 0 0 0.35rem;
    font-family: var(--serif);
    font-size: 1.35rem;
}

.empty-copy {
    margin: 0;
    color: var(--muted);
}

/* ---------- progress ---------- */

.progress-list {
    list-style: none;
    margin: 0.8rem 0 0;
    padding: 0;
}

.progress-list li {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.5rem 0;
    border-top: 1px solid var(--card-border);
    font-size: 0.95rem;
}

.progress-list li:first-child {
    border-top: 0;
}

.done {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    color: var(--accent);
    font-weight: 600;
}

.done svg {
    fill: var(--accent) !important;
}

.muted {
    color: var(--muted);
}

.teacher-actions {
    display: flex;
    gap: 0.6rem;
    margin-top: 0.85rem;
}

.form-block + .form-block,
.form-block + fluent-card,
fluent-card + fluent-card {
    margin-top: 0;
}

/* ---------- inputs ---------- */

input[type="file"] {
    display: block;
    margin: 0.75rem 0;
    font-family: var(--sans);
    color: var(--muted);
}

input[type="file"]::file-selector-button {
    background: var(--neutral-layer-3);
    color: var(--ink);
    border: 1px solid var(--neutral-stroke-rest);
    border-radius: 8px;
    padding: 0.42rem 0.95rem;
    margin-right: 0.75rem;
    font-family: inherit;
    font-size: 0.9rem;
    cursor: pointer;
    transition: background 0.15s ease, border-color 0.15s ease;
}

input[type="file"]::file-selector-button:hover {
    background: var(--neutral-layer-4);
    border-color: var(--neutral-stroke-hover);
}

fluent-text-field,
fluent-text-area,
fluent-number-field {
    width: 100% !important;
    max-width: 100%;
    min-width: 0 !important;
    display: block;
    box-sizing: border-box;
}

fluent-text-area::part(control),
fluent-text-field::part(control) {
    width: 100%;
    max-width: 100%;
    min-width: 0;
    font-size: 16px;
}

@media (max-width: 640px) {
    .page-body {
        padding: 1.25rem 1rem calc(5rem + env(safe-area-inset-bottom, 0px));
    }

    header.site-header,
    fluent-header.site-header {
        height: auto !important;
        min-height: 56px;
        flex-wrap: wrap;
        padding: 0.55rem 1rem !important;
        row-gap: 0.35rem;
    }

    .nav {
        flex-wrap: wrap;
        justify-content: flex-end;
    }

    .lesson-row {
        flex-direction: column;
        align-items: flex-start;
    }

    fluent-card {
        padding: 1rem;
    }

    fluent-stack {
        flex-wrap: wrap !important;
        max-width: 100%;
    }
}