/* ==========================================================================
   AEGIS SECURITY — Design System
   A premium cybersecurity interface.
   Palette: graphite, slate, muted navy with restrained teal accent.
   ========================================================================== */

/* --- Tokens ------------------------------------------------------------ */
:root {
    /* Backgrounds — layered graphite, never pure black */
    --bg-base:       #0c0d12;
    --bg-surface:    #13141b;
    --bg-raised:     #1a1c25;
    --bg-elevated:   #21232e;
    --bg-hover:      #272a36;

    /* Borders — nearly invisible, structural only */
    --border-subtle:  rgba(255, 255, 255, 0.055);
    --border-default: rgba(255, 255, 255, 0.08);
    --border-strong:  rgba(255, 255, 255, 0.12);

    /* Text — warm off-whites */
    --text-primary:   #edeef1;
    --text-secondary: #878a9a;
    --text-tertiary:  #555869;

    /* Accent — muted teal, not saturated blue */
    --accent:        #5eead4;
    --accent-dim:    rgba(94, 234, 212, 0.12);
    --accent-subtle: rgba(94, 234, 212, 0.06);
    --accent-hover:  #2dd4bf;

    /* Semantic */
    --danger:        #f87171;
    --danger-dim:    rgba(248, 113, 113, 0.10);
    --danger-border: rgba(248, 113, 113, 0.25);
    --success:       #86efac;
    --success-dim:   rgba(134, 239, 172, 0.10);
    --success-border:rgba(134, 239, 172, 0.25);
    --warning:       #fbbf24;
    --warning-dim:   rgba(251, 191, 36, 0.10);
    --warning-border:rgba(251, 191, 36, 0.25);

    /* Radii */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 20px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.25);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 30px rgba(0,0,0,0.35);

    /* Layout */
    --container-max: 1080px;
    --nav-height: 56px;
}

/* --- Reset ------------------------------------------------------------- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html { -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    background: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    font-size: 15px;
}

a { color: inherit; text-decoration: none; }
button { font-family: inherit; }
img { display: block; max-width: 100%; }

/* --- Typography -------------------------------------------------------- */
.t-display {
    font-size: 2.5rem;
    font-weight: 650;
    letter-spacing: -0.035em;
    line-height: 1.15;
}
.t-heading {
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    line-height: 1.3;
}
.t-title {
    font-size: 1.125rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    line-height: 1.4;
}
.t-body {
    font-size: 0.9375rem;
    font-weight: 400;
    line-height: 1.65;
}
.t-small {
    font-size: 0.8125rem;
    font-weight: 400;
    line-height: 1.55;
}
.t-micro {
    font-size: 0.6875rem;
    font-weight: 550;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    line-height: 1;
}

/* --- Navbar ------------------------------------------------------------ */
.navbar {
    position: sticky;
    top: 0;
    z-index: 100;
    height: var(--nav-height);
    background: rgba(12, 13, 18, 0.82);
    backdrop-filter: blur(16px) saturate(1.6);
    -webkit-backdrop-filter: blur(16px) saturate(1.6);
    border-bottom: 1px solid var(--border-subtle);
}

.nav-inner {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

/* Brand */
.nav-brand {
    display: flex;
    align-items: center;
    gap: 9px;
}

.nav-brand svg {
    width: 22px;
    height: 22px;
    flex-shrink: 0;
}

.nav-brand-text {
    font-size: 0.9375rem;
    font-weight: 650;
    letter-spacing: -0.01em;
    color: var(--text-primary);
}

/* Nav links */
.nav-links {
    display: flex;
    list-style: none;
    gap: 2px;
}

.nav-links a {
    display: block;
    padding: 6px 14px;
    font-size: 0.8125rem;
    font-weight: 480;
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: color 0.15s, background 0.15s;
}

.nav-links a:hover {
    color: var(--text-primary);
    background: var(--bg-raised);
}

.nav-links a.active {
    color: var(--text-primary);
    background: var(--bg-raised);
}

/* Mobile toggle */
.nav-toggle {
    display: none;
    width: 32px;
    height: 32px;
    align-items: center;
    justify-content: center;
    background: none;
    border: none;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: background 0.15s;
}

.nav-toggle:hover { background: var(--bg-raised); }

.nav-toggle svg {
    width: 18px;
    height: 18px;
    color: var(--text-secondary);
}

/* --- Layout ------------------------------------------------------------ */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
}

.page {
    padding-top: 48px;
    padding-bottom: 80px;
}

.section { margin-top: 56px; }
.section:first-child { margin-top: 0; }

/* --- Buttons ----------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 7px;
    height: 38px;
    padding: 0 18px;
    font-size: 0.8125rem;
    font-weight: 550;
    border-radius: var(--radius-sm);
    border: none;
    cursor: pointer;
    transition: all 0.15s ease;
    white-space: nowrap;
}

.btn svg { width: 15px; height: 15px; flex-shrink: 0; }

.btn-primary {
    background: var(--accent);
    color: #0c0d12;
}
.btn-primary:hover { background: var(--accent-hover); }
.btn-primary:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-secondary {
    background: var(--bg-elevated);
    color: var(--text-primary);
    border: 1px solid var(--border-default);
}
.btn-secondary:hover { background: var(--bg-hover); border-color: var(--border-strong); }

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
}
.btn-ghost:hover { color: var(--text-primary); background: var(--bg-raised); }

.btn-danger {
    background: var(--danger-dim);
    color: var(--danger);
    border: 1px solid var(--danger-border);
}
.btn-danger:hover { background: rgba(248,113,113,0.16); }

.btn-lg { height: 44px; padding: 0 24px; font-size: 0.875rem; border-radius: var(--radius-md); }
.btn-sm { height: 32px; padding: 0 12px; font-size: 0.75rem; }

/* --- Card -------------------------------------------------------------- */
.card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 28px;
}

.card-elevated {
    background: var(--bg-raised);
    border-color: var(--border-default);
}

/* --- Badge ------------------------------------------------------------- */
.badge {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 3px 10px;
    font-size: 0.6875rem;
    font-weight: 560;
    letter-spacing: 0.03em;
    border-radius: 100px;
    line-height: 1;
    height: 22px;
}

.badge-default {
    background: var(--bg-elevated);
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
}

.badge-accent {
    background: var(--accent-dim);
    color: var(--accent);
}

.badge-danger {
    background: var(--danger-dim);
    color: var(--danger);
}

.badge-success {
    background: var(--success-dim);
    color: var(--success);
}

.badge-warning {
    background: var(--warning-dim);
    color: var(--warning);
}

/* --- Hero (Home) ------------------------------------------------------- */
.hero {
    text-align: center;
    padding: 72px 0 20px;
    max-width: 640px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 5px 14px 5px 10px;
    font-size: 0.75rem;
    font-weight: 520;
    color: var(--text-secondary);
    background: var(--bg-raised);
    border: 1px solid var(--border-default);
    border-radius: 100px;
    margin-bottom: 24px;
}

.hero-badge-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--accent);
    flex-shrink: 0;
}

.hero h1 {
    font-size: 3rem;
    font-weight: 700;
    letter-spacing: -0.04em;
    line-height: 1.1;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.hero-sub {
    font-size: 1.0625rem;
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 480px;
    margin: 0 auto 36px;
}

.hero-actions {
    display: flex;
    gap: 10px;
    justify-content: center;
}

/* --- Feature Grid (Home) ----------------------------------------------- */
.features-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1px;
    background: var(--border-subtle);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-top: 56px;
}

.feature-item {
    background: var(--bg-surface);
    padding: 32px 28px;
    transition: background 0.2s;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.feature-item:hover { background: var(--bg-raised); }

.feature-item-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
}

.feature-item-icon svg { width: 18px; height: 18px; }

.feature-item h3 {
    font-size: 0.9375rem;
    font-weight: 580;
    letter-spacing: -0.01em;
    color: var(--text-primary);
}

.feature-item p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.feature-item .feature-link {
    font-size: 0.8125rem;
    font-weight: 520;
    color: var(--accent);
    margin-top: auto;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    transition: gap 0.15s;
}

.feature-item:hover .feature-link { gap: 7px; }

/* --- Page Header ------------------------------------------------------- */
.page-header {
    padding-bottom: 36px;
    border-bottom: 1px solid var(--border-subtle);
    margin-bottom: 36px;
}

.page-header h1 {
    font-size: 1.625rem;
    font-weight: 650;
    letter-spacing: -0.025em;
    margin-bottom: 6px;
}

.page-header p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    max-width: 520px;
}

/* --- Detect ------------------------------------------------------------ */
.detect-layout {
    max-width: 680px;
    margin: 0 auto;
}

.detect-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.detect-tabs {
    display: flex;
    border-bottom: 1px solid var(--border-subtle);
}

.detect-tab {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 7px;
    padding: 14px 16px;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-tertiary);
    background: none;
    border: none;
    cursor: pointer;
    transition: color 0.15s, background 0.15s;
    position: relative;
}

.detect-tab svg { width: 15px; height: 15px; }

.detect-tab:hover {
    color: var(--text-secondary);
    background: var(--bg-raised);
}

.detect-tab.active {
    color: var(--text-primary);
    background: var(--bg-raised);
}

.detect-tab.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 16px;
    right: 16px;
    height: 2px;
    background: var(--accent);
    border-radius: 2px 2px 0 0;
}

.detect-body { padding: 24px; }

.detect-panel { display: none; }
.detect-panel.active { display: block; }

/* Textarea */
.input-area {
    width: 100%;
    min-height: 160px;
    background: var(--bg-base);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    padding: 14px 16px;
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.875rem;
    line-height: 1.65;
    resize: vertical;
    transition: border-color 0.15s, box-shadow 0.15s;
}

.input-area:focus {
    outline: none;
    border-color: rgba(94, 234, 212, 0.35);
    box-shadow: 0 0 0 3px rgba(94, 234, 212, 0.08);
}

.input-area::placeholder { color: var(--text-tertiary); }

.detect-actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 16px;
}

.detect-hint {
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

/* File upload */
.upload-zone {
    border: 1px dashed var(--border-default);
    border-radius: var(--radius-md);
    padding: 32px 24px;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
}

.upload-zone:hover {
    border-color: var(--border-strong);
    background: var(--bg-raised);
}

.upload-zone input[type="file"] { display: none; }

.upload-zone-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 12px;
    color: var(--text-tertiary);
}

.upload-zone-icon svg { width: 18px; height: 18px; }

.upload-zone-label {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.upload-zone-sub {
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

.upload-file-name {
    font-size: 0.8125rem;
    color: var(--accent);
    font-weight: 520;
    margin-top: 8px;
}

.detect-divider {
    text-align: center;
    padding: 16px 0;
    font-size: 0.75rem;
    color: var(--text-tertiary);
    position: relative;
}

.detect-divider::before,
.detect-divider::after {
    content: '';
    position: absolute;
    top: 50%;
    width: calc(50% - 24px);
    height: 1px;
    background: var(--border-subtle);
}
.detect-divider::before { left: 0; }
.detect-divider::after { right: 0; }

/* --- Analysis Result --------------------------------------------------- */
.result-container {
    margin-top: 20px;
    display: none;
}
.result-container.show {
    display: block;
    animation: resultReveal 0.3s ease;
}

@keyframes resultReveal {
    from { opacity: 0; transform: translateY(8px); }
    to   { opacity: 1; transform: translateY(0); }
}

.result-panel {
    border-radius: var(--radius-md);
    padding: 20px;
}

.result-panel.is-threat {
    background: var(--danger-dim);
    border: 1px solid var(--danger-border);
}

.result-panel.is-safe {
    background: var(--success-dim);
    border: 1px solid var(--success-border);
}

.result-panel.is-error {
    background: var(--bg-raised);
    border: 1px solid var(--border-default);
}

.result-header {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    margin-bottom: 16px;
}

.result-status-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.is-threat .result-status-icon {
    background: rgba(248, 113, 113, 0.15);
    color: var(--danger);
}

.is-safe .result-status-icon {
    background: rgba(134, 239, 172, 0.15);
    color: var(--success);
}

.result-status-icon svg { width: 20px; height: 20px; }

.result-label {
    font-size: 1.0625rem;
    font-weight: 620;
    letter-spacing: -0.01em;
    margin-bottom: 2px;
}

.is-threat .result-label { color: var(--danger); }
.is-safe .result-label { color: var(--success); }

.result-meta {
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

/* Confidence meter */
.confidence-meter {
    margin-bottom: 16px;
}

.confidence-meter-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.75rem;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.confidence-meter-label strong {
    font-weight: 600;
    color: var(--text-primary);
}

.confidence-track {
    height: 4px;
    background: rgba(255,255,255,0.06);
    border-radius: 2px;
    overflow: hidden;
}

.confidence-fill {
    height: 100%;
    border-radius: 2px;
    transition: width 0.5s ease;
}

.is-threat .confidence-fill { background: var(--danger); }
.is-safe .confidence-fill { background: var(--success); }

.result-transcript {
    margin-top: 12px;
    padding: 12px 14px;
    background: rgba(0,0,0,0.2);
    border-radius: var(--radius-sm);
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
    display: none;
}

.result-transcript strong {
    color: var(--text-primary);
    font-weight: 560;
}

.result-actions {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

/* Loading */
.loader {
    display: none;
    padding: 28px;
    text-align: center;
}
.loader.show { display: block; }

.loader-spinner {
    width: 28px;
    height: 28px;
    border: 2px solid var(--border-default);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: loaderSpin 0.7s linear infinite;
    margin: 0 auto 12px;
}

@keyframes loaderSpin { to { transform: rotate(360deg); } }

.loader-text {
    font-size: 0.8125rem;
    color: var(--text-tertiary);
}

/* --- Library ----------------------------------------------------------- */
.library-search {
    position: relative;
    margin-bottom: 28px;
}

.library-search input {
    width: 100%;
    height: 42px;
    padding: 0 14px 0 40px;
    background: var(--bg-surface);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.8125rem;
    font-family: inherit;
    transition: border-color 0.15s, box-shadow 0.15s;
}

.library-search input:focus {
    outline: none;
    border-color: rgba(94, 234, 212, 0.3);
    box-shadow: 0 0 0 3px rgba(94, 234, 212, 0.06);
}

.library-search input::placeholder { color: var(--text-tertiary); }

.library-search-icon {
    position: absolute;
    left: 13px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-tertiary);
    pointer-events: none;
}

.library-search-icon svg { width: 15px; height: 15px; }

.library-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
    gap: 12px;
}

.library-card {
    display: block;
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 22px 24px;
    transition: border-color 0.2s, background 0.2s;
}

.library-card:hover {
    border-color: var(--border-strong);
    background: var(--bg-raised);
}

.library-card-top {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 10px;
}

.library-card-arrow {
    color: var(--text-tertiary);
    transition: color 0.15s, transform 0.15s;
}

.library-card-arrow svg { width: 14px; height: 14px; }

.library-card:hover .library-card-arrow {
    color: var(--text-secondary);
    transform: translateX(2px);
}

.library-card h3 {
    font-size: 0.9375rem;
    font-weight: 580;
    letter-spacing: -0.01em;
    margin-bottom: 6px;
    color: var(--text-primary);
}

.library-card p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.library-empty {
    text-align: center;
    padding: 48px 24px;
    color: var(--text-tertiary);
    display: none;
}

.library-empty p:first-child {
    font-size: 0.9375rem;
    font-weight: 520;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

/* --- Detail pages (Library detail & Guidance) -------------------------- */
.back-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.8125rem;
    font-weight: 480;
    color: var(--text-tertiary);
    margin-bottom: 28px;
    transition: color 0.15s;
}
.back-link:hover { color: var(--text-secondary); }
.back-link svg { width: 14px; height: 14px; }

.detail-header {
    margin-bottom: 40px;
}

.detail-header h1 {
    font-size: 1.75rem;
    font-weight: 660;
    letter-spacing: -0.03em;
    margin-top: 10px;
    margin-bottom: 10px;
}

.detail-header p {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    line-height: 1.7;
    max-width: 640px;
}

.detail-section {
    margin-bottom: 32px;
}

.detail-section-title {
    font-size: 0.8125rem;
    font-weight: 580;
    letter-spacing: -0.005em;
    color: var(--text-primary);
    margin-bottom: 14px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.detail-section-title svg { width: 16px; height: 16px; color: var(--text-tertiary); }

.detail-list {
    list-style: none;
    padding: 0;
}

.detail-list li {
    position: relative;
    padding: 8px 0 8px 20px;
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

.detail-list li::before {
    content: '';
    position: absolute;
    left: 2px;
    top: 15px;
    width: 5px;
    height: 5px;
    border-radius: 50%;
    background: var(--text-tertiary);
}

.detail-list li + li {
    border-top: 1px solid var(--border-subtle);
}

/* Video */
.video-embed {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    border-radius: var(--radius-md);
    overflow: hidden;
    background: var(--bg-base);
}

.video-embed iframe {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    border: none;
}

/* --- Guidance Alert ---------------------------------------------------- */
.guidance-banner {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 20px 24px;
    background: var(--warning-dim);
    border: 1px solid var(--warning-border);
    border-radius: var(--radius-lg);
    margin-bottom: 36px;
}

.guidance-banner-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-sm);
    background: rgba(251, 191, 36, 0.15);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    color: var(--warning);
}

.guidance-banner-icon svg { width: 18px; height: 18px; }

.guidance-banner h3 {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--warning);
    margin-bottom: 4px;
}

.guidance-banner p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* --- Quiz -------------------------------------------------------------- */
.quiz-layout {
    max-width: 620px;
    margin: 0 auto;
}

/* Start screen */
.quiz-start {
    text-align: center;
    padding: 48px 24px;
}

.quiz-start-icon {
    width: 52px;
    height: 52px;
    border-radius: var(--radius-md);
    background: var(--accent-dim);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    color: var(--accent);
}

.quiz-start-icon svg { width: 24px; height: 24px; }

.quiz-start h2 {
    font-size: 1.25rem;
    font-weight: 620;
    letter-spacing: -0.015em;
    margin-bottom: 8px;
}

.quiz-start p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    max-width: 380px;
    margin: 0 auto 24px;
    line-height: 1.65;
}

/* Progress */
.quiz-progress {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
}

.progress-track {
    flex: 1;
    height: 3px;
    background: var(--bg-elevated);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--accent);
    border-radius: 2px;
    transition: width 0.35s ease;
}

.progress-label {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    font-weight: 520;
    white-space: nowrap;
    font-variant-numeric: tabular-nums;
}

/* Question card */
.question-card {
    background: var(--bg-surface);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 28px;
}

.question-text {
    font-size: 0.9375rem;
    font-weight: 500;
    line-height: 1.65;
    color: var(--text-primary);
    margin-bottom: 20px;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.quiz-option {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px 14px;
    background: var(--bg-base);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
}

.quiz-option:hover {
    border-color: var(--border-strong);
    background: var(--bg-raised);
}

.quiz-option.selected {
    border-color: rgba(94, 234, 212, 0.4);
    background: var(--accent-subtle);
}

.quiz-option.correct {
    border-color: var(--success-border);
    background: var(--success-dim);
}

.quiz-option.incorrect {
    border-color: var(--danger-border);
    background: var(--danger-dim);
}

.option-letter {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 650;
    background: var(--bg-elevated);
    border: 1px solid var(--border-default);
    color: var(--text-secondary);
    flex-shrink: 0;
    transition: all 0.15s;
}

.quiz-option.selected .option-letter {
    background: var(--accent);
    border-color: var(--accent);
    color: var(--bg-base);
}

.quiz-option.correct .option-letter {
    background: var(--success);
    border-color: var(--success);
    color: var(--bg-base);
}

.quiz-option.incorrect .option-letter {
    background: var(--danger);
    border-color: var(--danger);
    color: #fff;
}

.option-text {
    font-size: 0.8125rem;
    color: var(--text-primary);
    line-height: 1.5;
}

.quiz-explanation {
    margin-top: 14px;
    padding: 14px 16px;
    background: var(--accent-subtle);
    border: 1px solid rgba(94, 234, 212, 0.15);
    border-radius: var(--radius-md);
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
    display: none;
}

.quiz-explanation.show {
    display: block;
    animation: resultReveal 0.25s ease;
}

.quiz-nav {
    display: flex;
    justify-content: flex-end;
    margin-top: 16px;
}

/* Results */
.quiz-results {
    text-align: center;
    padding: 36px 24px;
}

.score-ring {
    width: 120px;
    height: 120px;
    border-radius: 50%;
    border: 3px solid var(--border-default);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
    transition: border-color 0.3s;
}

.score-value {
    font-size: 2rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1;
}

.score-unit {
    font-size: 0.6875rem;
    font-weight: 550;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-tertiary);
    margin-top: 2px;
}

.quiz-results h2 {
    font-size: 1.25rem;
    font-weight: 620;
    margin-bottom: 4px;
}

.quiz-results .results-sub {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
}

.results-actions {
    display: flex;
    gap: 8px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 32px;
}

.breakdown-title {
    font-size: 0.8125rem;
    font-weight: 580;
    color: var(--text-primary);
    text-align: left;
    margin-bottom: 12px;
}

.breakdown-item {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 12px 14px;
    background: var(--bg-base);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    margin-bottom: 6px;
    text-align: left;
}

.breakdown-icon {
    width: 22px;
    height: 22px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.breakdown-icon svg { width: 12px; height: 12px; }

.breakdown-icon.is-correct {
    background: var(--success-dim);
    color: var(--success);
}

.breakdown-icon.is-wrong {
    background: var(--danger-dim);
    color: var(--danger);
}

.breakdown-q {
    font-size: 0.8125rem;
    color: var(--text-primary);
    line-height: 1.5;
    margin-bottom: 2px;
}

.breakdown-exp {
    font-size: 0.75rem;
    color: var(--text-secondary);
    line-height: 1.55;
}

/* --- Footer ------------------------------------------------------------ */
.footer {
    border-top: 1px solid var(--border-subtle);
    padding: 24px 0;
    margin-top: 80px;
}

.footer-inner {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.footer-text {
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

.footer-links {
    display: flex;
    gap: 16px;
}

.footer-links a {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    transition: color 0.15s;
}

.footer-links a:hover { color: var(--text-secondary); }

/* --- Utility ----------------------------------------------------------- */
.sr-only {
    position: absolute; width: 1px; height: 1px;
    padding: 0; margin: -1px; overflow: hidden;
    clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

.text-secondary { color: var(--text-secondary); }
.text-tertiary { color: var(--text-tertiary); }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.mb-4 { margin-top: 16px; }

/* --- Responsive -------------------------------------------------------- */
@media (max-width: 768px) {
    :root { --nav-height: 52px; }

    .nav-toggle { display: flex; }

    .nav-links {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0; right: 0;
        background: var(--bg-surface);
        border-bottom: 1px solid var(--border-subtle);
        flex-direction: column;
        padding: 8px;
    }
    .nav-links.open { display: flex; }

    .hero { padding: 48px 0 16px; }
    .hero h1 { font-size: 2.125rem; }
    .hero-sub { font-size: 0.9375rem; }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .page { padding-top: 32px; padding-bottom: 56px; }

    .library-grid {
        grid-template-columns: 1fr;
    }

    .card { padding: 20px; }
    .question-card { padding: 20px; }

    .footer-inner {
        flex-direction: column;
        gap: 12px;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero h1 { font-size: 1.75rem; }
    .hero-actions { flex-direction: column; align-items: center; }
    .detect-tab { font-size: 0.75rem; padding: 12px 8px; }
    .detect-tab svg { display: none; }
    .result-actions { flex-direction: column; }
}