/* Design System & Color Tokens */
:root {
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    --font-mono: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, Courier, monospace;

    /* Light Theme Tokens */
    --bg-canvas: #f8fafc;
    --bg-card: #ffffff;
    --bg-subtle: #f1f5f9;
    --bg-input: #ffffff;
    --border-color: #e2e8f0;
    --border-hover: #cbd5e1;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --accent-subtle: #dbeafe;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.07);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.08);

    /* Badge Colors */
    --badge-std-bg: #ecfdf5;
    --badge-std-text: #047857;
    --badge-cand-bg: #e0f2fe;
    --badge-cand-text: #0369a1;
    --badge-note-bg: #fef3c7;
    --badge-note-text: #92400e;
    --badge-rep-bg: #f3e8ff;
    --badge-rep-text: #6b21a8;
    --badge-leg-bg: #f1f5f9;
    --badge-leg-text: #334155;
}

[data-theme="dark"] {
    --bg-canvas: #090d16;
    --bg-card: #111827;
    --bg-subtle: #1f2937;
    --bg-input: #111827;
    --border-color: #1f2937;
    --border-hover: #374151;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #60a5fa;
    --accent-subtle: rgba(59, 130, 246, 0.15);
    --shadow-sm: 0 1px 3px 0 rgb(0 0 0 / 0.3);
    --shadow-md: 0 4px 8px -1px rgb(0 0 0 / 0.4);
    --shadow-lg: 0 12px 20px -3px rgb(0 0 0 / 0.5);

    --badge-std-bg: rgba(16, 185, 129, 0.15);
    --badge-std-text: #34d399;
    --badge-cand-bg: rgba(56, 189, 248, 0.15);
    --badge-cand-text: #38bdf8;
    --badge-note-bg: rgba(245, 158, 11, 0.15);
    --badge-note-text: #fbbf24;
    --badge-rep-bg: rgba(168, 85, 247, 0.15);
    --badge-rep-text: #c084fc;
    --badge-leg-bg: rgba(100, 116, 139, 0.2);
    --badge-leg-text: #94a3b8;
}

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

/* Accessibility: Skip Navigation Links */
.skip-link {
    position: absolute;
    top: -200px;
    left: 1rem;
    background: var(--accent);
    color: #ffffff !important;
    padding: 0.75rem 1.25rem;
    border-radius: 0 0 8px 8px;
    font-size: 0.95rem;
    font-weight: 700;
    z-index: 10000;
    text-decoration: none;
    box-shadow: var(--shadow-lg);
    transition: top 0.15s ease-in-out;
}

.skip-link:focus {
    top: 0;
    outline: 3px solid #ffffff !important;
    outline-offset: 2px !important;
}

/* Accessibility: Universal High-Contrast Focus Visible */
*:focus-visible {
    outline: 2px solid var(--accent) !important;
    outline-offset: 2px !important;
}

/* Reset & Global */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-canvas);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.2s ease, color 0.2s ease;
    min-height: 100vh;
}

.app-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2rem 1.5rem 4rem;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.brand-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.brand-logo {
    width: 44px;
    height: 44px;
    background: linear-gradient(135deg, #2563eb, #8b5cf6);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: #fff;
    box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

.app-title {
    font-size: 1.75rem;
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text-primary);
}

.app-subtitle {
    font-size: 0.95rem;
    color: var(--text-muted);
}

.header-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.theme-btn {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 0.85rem;
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
}

.theme-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Stats Ribbon */
.stats-ribbon {
    display: flex;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.stat-item {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-size: 0.85rem;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.stat-item strong {
    color: var(--accent);
    font-size: 1rem;
}

/* Search Box */
.search-section {
    margin-bottom: 1.5rem;
}

.search-input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon {
    position: absolute;
    left: 1.25rem;
    font-size: 1.2rem;
    color: var(--text-muted);
    pointer-events: none;
}

.search-input {
    width: 100%;
    padding: 1rem 13rem 1rem 3.25rem;
    font-size: 1.15rem;
    font-family: inherit;
    background: var(--bg-input);
    border: 2px solid var(--border-color);
    border-radius: 14px;
    color: var(--text-primary);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 4px var(--accent-subtle);
}

.search-input-actions {
    position: absolute;
    right: 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.45rem;
}

.clear-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 1.15rem;
    display: none;
    padding: 0.35rem 0.5rem;
    min-width: 28px;
    min-height: 28px;
    border-radius: 4px;
    transition: color 0.15s ease;
}

.clear-btn:hover {
    color: var(--text-primary);
}

.syntax-guide-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    background: var(--bg-subtle);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.35rem 0.65rem;
    border-radius: 8px;
    font-size: 0.82rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    user-select: none;
}

.syntax-guide-btn:hover {
    background: var(--accent-subtle);
    border-color: var(--accent);
    color: var(--accent);
    transform: translateY(-1px);
}

.syntax-icon {
    font-size: 0.95rem;
}

.search-shortcut {
    background: var(--bg-subtle);
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    padding: 0.2rem 0.5rem;
    border-radius: 6px;
    font-size: 0.75rem;
    font-family: var(--font-mono);
    pointer-events: none;
}

/* Quick Topic Pills */
.quick-tags-wrapper {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-top: 0.75rem;
    flex-wrap: wrap;
}

.quick-tags-label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
}

.quick-tag {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.3rem 0.7rem;
    border-radius: 20px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.15s ease;
}

.quick-tag:hover {
    border-color: var(--accent);
    color: var(--accent);
    background: var(--accent-subtle);
}

/* Filter Controls Bar */
.filter-bar {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem;
    margin-bottom: 0.75rem;
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
    justify-content: space-between;
}

.filter-group {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    align-items: center;
}

/* Multi-Select Dropdown Component */
.dropdown-multiselect {
    position: relative;
    user-select: none;
}

.dropdown-trigger {
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.5rem 0.85rem;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    outline: none;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.15s ease;
}

.dropdown-trigger:hover {
    border-color: var(--border-hover);
}

.dropdown-multiselect.open .dropdown-trigger,
.dropdown-trigger.has-selection {
    border-color: var(--accent);
}

.dropdown-badge {
    background: var(--accent);
    color: #fff;
    font-size: 0.7rem;
    font-weight: 700;
    border-radius: 10px;
    padding: 0.1rem 0.45rem;
    line-height: 1;
}

.dropdown-arrow {
    font-size: 0.75rem;
    color: var(--text-muted);
    transition: transform 0.2s ease;
}

.dropdown-multiselect.open .dropdown-arrow {
    transform: rotate(180deg);
}

.dropdown-menu {
    position: absolute;
    top: calc(100% + 6px);
    left: 0;
    min-width: 260px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    box-shadow: var(--shadow-lg);
    z-index: 100;
    display: none;
    opacity: 0;
    transform: translateY(-4px);
    transition: opacity 0.15s ease, transform 0.15s ease;
}

.dropdown-multiselect.open .dropdown-menu {
    display: block;
    opacity: 1;
    transform: translateY(0);
}

.dropdown-menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.6rem 0.85rem;
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-subtle);
    border-top-left-radius: 10px;
    border-top-right-radius: 10px;
}

.dropdown-menu-title {
    font-size: 0.78rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.03em;
    color: var(--text-muted);
}

.dropdown-actions {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.dropdown-action-btn {
    background: none;
    border: none;
    color: var(--accent);
    font-size: 0.78rem;
    font-weight: 500;
    cursor: pointer;
    padding: 0;
}

.dropdown-action-btn:hover {
    text-decoration: underline;
}

.dropdown-action-sep {
    color: var(--text-muted);
    font-size: 0.7rem;
}

.dropdown-options-list {
    max-height: 250px;
    overflow-y: auto;
    padding: 0.4rem 0;
}

.dropdown-option {
    display: flex;
    align-items: center;
    padding: 0.45rem 0.85rem;
    cursor: pointer;
    transition: background-color 0.1s ease;
    gap: 0.6rem;
}

.dropdown-option:hover {
    background-color: var(--bg-subtle);
}

.dropdown-option input[type="checkbox"] {
    accent-color: var(--accent);
    cursor: pointer;
    width: 15px;
    height: 15px;
}

.dropdown-option label {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
    font-size: 0.85rem;
    color: var(--text-primary);
}

.option-count {
    font-size: 0.75rem;
    color: var(--text-muted);
    background: var(--bg-subtle);
    padding: 0.1rem 0.4rem;
    border-radius: 10px;
    font-family: var(--font-mono);
}

/* Active Filter Pills Bar */
.active-filters-bar {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.6rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 0.6rem 1rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
}

.active-filters-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.active-filter-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    align-items: center;
}

.active-chip {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    background: var(--accent-subtle);
    color: var(--accent);
    padding: 0.2rem 0.6rem;
    border-radius: 16px;
    font-size: 0.78rem;
    font-weight: 500;
    border: 1px solid rgba(37, 99, 235, 0.2);
}

[data-theme="dark"] .active-chip {
    border-color: rgba(59, 130, 246, 0.3);
}

.active-chip-type {
    opacity: 0.7;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
}

.active-chip-remove {
    background: none;
    border: none;
    color: inherit;
    font-size: 0.85rem;
    cursor: pointer;
    line-height: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.2rem 0.35rem;
    min-width: 24px;
    min-height: 24px;
    opacity: 0.8;
    transition: opacity 0.1s ease;
}

.active-chip-remove:hover {
    opacity: 1;
}

.clear-all-filters-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    padding: 0.2rem 0.4rem;
    margin-left: auto;
    transition: color 0.15s ease;
}

.clear-all-filters-btn:hover {
    color: #ef4444;
    text-decoration: underline;
}

/* Scope Toggle */
.scope-toggle {
    display: flex;
    background: var(--bg-subtle);
    padding: 3px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.scope-btn {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    padding: 0.4rem 0.85rem;
    font-size: 0.82rem;
    font-weight: 500;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.15s ease;
}

.scope-btn.active {
    background: var(--bg-card);
    color: var(--accent);
    box-shadow: var(--shadow-sm);
    font-weight: 600;
}

/* Results Section */
.results-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.results-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Result Card */
.result-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.25rem 1.5rem;
    box-shadow: var(--shadow-sm);
    transition: transform 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}

.result-card:hover {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-md);
    transform: translateY(-1px);
}

.result-section {
    border-left: 4px solid var(--accent);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 0.6rem;
}

.card-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
}

.badge {
    display: inline-block;
    padding: 0.2rem 0.55rem;
    border-radius: 6px;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.02em;
    text-transform: uppercase;
}

.badge-type.badge-standard {
    background: var(--badge-std-bg);
    color: var(--badge-std-text);
}

.badge-type.badge-candidate {
    background: var(--badge-cand-bg);
    color: var(--badge-cand-text);
}

.badge-type.badge-draft {
    background: rgba(14, 165, 233, 0.15);
    color: #0284c7;
}

[data-theme="dark"] .badge-type.badge-draft {
    background: rgba(56, 189, 248, 0.15);
    color: #38bdf8;
}

.badge-type.badge-note {
    background: var(--badge-note-bg);
    color: var(--badge-note-text);
}

.badge-type.badge-report {
    background: var(--badge-rep-bg);
    color: var(--badge-rep-text);
}

.badge-type.badge-legacy {
    background: var(--badge-leg-bg);
    color: var(--badge-leg-text);
}

.badge-pub {
    background: var(--bg-subtle);
    color: var(--text-secondary);
}

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

.badge-ver, .badge-sec {
    background: var(--bg-subtle);
    color: var(--text-muted);
}

.external-link-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.35rem 0.75rem;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent);
    background: var(--accent-subtle);
    border-radius: 6px;
    text-decoration: none;
    white-space: nowrap;
    transition: background 0.15s ease;
}

.external-link-btn:hover {
    background: var(--accent);
    color: #fff;
}

.card-title {
    font-size: 1.15rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
    line-height: 1.4;
}

.card-title a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color 0.15s ease;
}

.card-title a:hover {
    color: var(--accent);
    text-decoration: underline;
}

.parent-source-note {
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.parent-source-note strong {
    color: var(--text-secondary);
}

.card-desc {
    font-size: 0.92rem;
    color: var(--text-secondary);
    margin-bottom: 0.85rem;
}

/* RFC 2119 Requirement Badges */
.card-rfc-container {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 0.85rem;
    padding: 0.4rem 0.65rem;
    background: var(--bg-subtle);
    border-radius: 8px;
    border: 1px dashed var(--border-color);
}

.rfc-title {
    font-size: 0.72rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: var(--text-muted);
}

.rfc-badges {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    align-items: center;
}

.badge-rfc {
    display: inline-flex;
    align-items: center;
    padding: 0.15rem 0.5rem;
    border-radius: 5px;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all 0.15s ease;
    user-select: none;
    line-height: 1.3;
}

.badge-rfc:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
    filter: brightness(0.95);
}

[data-theme="dark"] .badge-rfc:hover {
    filter: brightness(1.15);
}

/* MUST / REQUIRED (Red/Rose) */
.badge-rfc-must,
.badge-rfc-required {
    background: #fee2e2;
    color: #b91c1c;
    border-color: #fca5a5;
}
[data-theme="dark"] .badge-rfc-must,
[data-theme="dark"] .badge-rfc-required {
    background: rgba(239, 68, 68, 0.15);
    color: #f87171;
    border-color: rgba(239, 68, 68, 0.35);
}

/* MUST NOT (Dark Crimson) */
.badge-rfc-must-not {
    background: #991b1b;
    color: #ffffff;
    border-color: #7f1d1d;
}
[data-theme="dark"] .badge-rfc-must-not {
    background: #7f1d1d;
    color: #fecaca;
    border-color: #ef4444;
}

/* SHOULD / RECOMMENDED (Amber) */
.badge-rfc-should,
.badge-rfc-recommended {
    background: #fef3c7;
    color: #92400e;
    border-color: #fcd34d;
}
[data-theme="dark"] .badge-rfc-should,
[data-theme="dark"] .badge-rfc-recommended {
    background: rgba(245, 158, 11, 0.15);
    color: #fbbf24;
    border-color: rgba(245, 158, 11, 0.35);
}

/* SHOULD NOT (Amber dashed) */
.badge-rfc-should-not {
    background: #fef3c7;
    color: #92400e;
    border-color: #f59e0b;
    border-style: dashed;
}
[data-theme="dark"] .badge-rfc-should-not {
    background: rgba(217, 119, 6, 0.2);
    color: #fde68a;
    border-color: #d97706;
    border-style: dashed;
}

/* MAY / OPTIONAL (Emerald/Green) */
.badge-rfc-may,
.badge-rfc-optional {
    background: #dcfce7;
    color: #15803d;
    border-color: #86efac;
}
[data-theme="dark"] .badge-rfc-may,
[data-theme="dark"] .badge-rfc-optional {
    background: rgba(34, 197, 94, 0.15);
    color: #4ade80;
    border-color: rgba(34, 197, 94, 0.35);
}

.card-keywords {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-bottom: 0.85rem;
}

.kw-tag {
    background: var(--bg-subtle);
    color: var(--text-muted);
    padding: 0.15rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-family: var(--font-mono);
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-top: 1px solid var(--border-color);
    padding-top: 0.6rem;
    font-size: 0.78rem;
    color: var(--text-muted);
}

.doc-url {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    max-width: 80%;
    font-family: var(--font-mono);
}

.copy-link-btn {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    cursor: pointer;
}

.copy-link-btn:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Keyword Highlights */
mark {
    background-color: rgba(253, 224, 71, 0.4);
    color: inherit;
    padding: 0.1rem 0.2rem;
    border-radius: 3px;
}

[data-theme="dark"] mark {
    background-color: rgba(234, 179, 8, 0.35);
    color: #fef08a;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: 4rem 1.5rem;
    background: var(--bg-card);
    border: 1px dashed var(--border-color);
    border-radius: 12px;
}

.empty-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.6;
}

.empty-state h3 {
    margin-bottom: 0.5rem;
    font-size: 1.25rem;
}

.empty-state p {
    color: var(--text-muted);
    font-size: 0.95rem;
}

.empty-state code {
    background: var(--bg-subtle);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-family: var(--font-mono);
}

/* Responsive */
@media (max-width: 768px) {
    .app-header {
        flex-direction: column;
        gap: 1rem;
    }
    .filter-bar {
        flex-direction: column;
        align-items: stretch;
    }
    .filter-group {
        flex-direction: column;
    }
    .dropdown-multiselect {
        width: 100%;
    }
    .dropdown-trigger {
        width: 100%;
        justify-content: space-between;
    }
    .dropdown-menu {
        width: 100%;
    }
    .card-header {
        flex-direction: column;
        align-items: flex-start;
    }
    .external-link-btn {
        width: 100%;
        justify-content: center;
    }
    .syntax-btn-text {
        display: none;
    }
    .search-input {
        padding-right: 6.5rem;
    }
}

/* Results Info Bar */
.results-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    flex-wrap: wrap;
    gap: 0.75rem;
}

.results-info-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.parsed-query-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    background: var(--accent-subtle);
    border: 1px solid var(--accent);
    color: var(--accent);
    padding: 0.2rem 0.65rem;
    border-radius: 9999px;
    font-size: 0.78rem;
    font-weight: 500;
    font-family: var(--font-mono);
}

/* Syntax Guide Modal Dialog */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.65);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.25s ease, visibility 0.25s ease;
    padding: 1.25rem;
}

.modal-overlay.open {
    opacity: 1;
    visibility: visible;
}

.modal-container {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    width: 100%;
    max-width: 860px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    transform: scale(0.95) translateY(10px);
    transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    overflow: hidden;
}

.modal-overlay.open .modal-container {
    transform: scale(1) translateY(0);
}

.modal-header {
    padding: 1.25rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-subtle);
}

.modal-header-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.modal-icon {
    font-size: 1.5rem;
}

.modal-title {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.modal-subtitle {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.modal-close-btn {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-muted);
    width: 32px;
    height: 32px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.15s ease;
}

.modal-close-btn:hover {
    background: var(--border-color);
    color: var(--text-primary);
}

.modal-body {
    padding: 1.5rem;
    overflow-y: auto;
}

.syntax-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 1rem;
}

.syntax-card {
    background: var(--bg-subtle);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    transition: border-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}

.syntax-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.syntax-card-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.syntax-card-header strong {
    font-size: 0.92rem;
    color: var(--text-primary);
}

.syntax-card p {
    font-size: 0.83rem;
    color: var(--text-secondary);
    line-height: 1.4;
    flex-grow: 1;
}

.syntax-badge {
    display: inline-block;
    padding: 0.15rem 0.45rem;
    border-radius: 6px;
    font-size: 0.72rem;
    font-weight: 700;
    font-family: var(--font-mono);
}

.syntax-and { background: rgba(16, 185, 129, 0.15); color: #047857; }
.syntax-or { background: rgba(59, 130, 246, 0.15); color: #1d4ed8; }
.syntax-not { background: rgba(239, 68, 68, 0.15); color: #b91c1c; }
.syntax-phrase { background: rgba(168, 85, 247, 0.15); color: #6b21a8; }
.syntax-group { background: rgba(245, 158, 11, 0.15); color: #92400e; }
.syntax-field { background: rgba(14, 165, 233, 0.15); color: #0369a1; }
.syntax-req { background: rgba(239, 68, 68, 0.15); color: #b91c1c; }
.syntax-prefix { background: rgba(100, 116, 139, 0.15); color: #334155; }
.syntax-complex { background: linear-gradient(135deg, rgba(59, 130, 246, 0.2), rgba(168, 85, 247, 0.2)); color: var(--accent); }

[data-theme="dark"] .syntax-and { color: #34d399; }
[data-theme="dark"] .syntax-or { color: #60a5fa; }
[data-theme="dark"] .syntax-not { color: #f87171; }
[data-theme="dark"] .syntax-phrase { color: #c084fc; }
[data-theme="dark"] .syntax-group { color: #fbbf24; }
[data-theme="dark"] .syntax-field { color: #38bdf8; }
[data-theme="dark"] .syntax-req { color: #f87171; }
[data-theme="dark"] .syntax-prefix { color: #94a3b8; }

.syntax-example {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 0.4rem 0.6rem;
    border-radius: 6px;
    margin-top: 0.35rem;
}

.syntax-example code {
    font-family: var(--font-mono);
    font-size: 0.8rem;
    color: var(--accent);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    padding-right: 0.5rem;
}

.use-example-btn {
    background: var(--accent-subtle);
    border: 1px solid var(--accent);
    color: var(--accent);
    padding: 0.2rem 0.55rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
    transition: all 0.15s ease;
}

.use-example-btn:hover {
    background: var(--accent);
    color: #fff;
}

.modal-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--bg-subtle);
    flex-wrap: wrap;
    gap: 0.75rem;
}

.modal-footer-tip {
    font-size: 0.82rem;
    color: var(--text-muted);
}

.modal-footer-tip kbd {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 0.15rem 0.35rem;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.75rem;
}

.modal-primary-btn {
    background: var(--accent);
    color: #fff;
    border: none;
    padding: 0.5rem 1.25rem;
    border-radius: 8px;
    font-weight: 600;
    font-size: 0.88rem;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

.modal-primary-btn:hover {
    background: var(--accent-hover);
}

/* Page Footer */
.app-footer {
    margin-top: 3rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.app-footer a {
    color: var(--accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}

.app-footer a:hover {
    color: var(--accent-hover);
}

/* Accessibility: Reduced Motion (WCAG 2.2.2 & 2.3.3) */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* Accessibility: Windows High Contrast / Forced Colors Mode */
@media (forced-colors: active) {
    .badge,
    .badge-rfc,
    .syntax-badge,
    .dropdown-badge,
    .scope-btn.active,
    .theme-btn,
    .skip-link,
    .modal-close-btn,
    .external-link-btn {
        forced-color-adjust: none;
        border: 1px solid ButtonText;
    }
    *:focus-visible {
        outline: 3px solid Highlight !important;
        outline-offset: 2px !important;
    }
}