/* ═══════════════════════════════════════════════
   EnvSeis Paper Tracker — Warm Earth Tones
   Fonts: Sora (headings) + Public Sans (body) + JetBrains Mono (mono)
   Palette: Parchment, terracotta, sage, ochre — organic & grounded
   ═══════════════════════════════════════════════ */

:root {
    --bg-primary: #faf6f0;
    --bg-secondary: #f0e9df;
    --bg-card: #ffffff;
    --bg-card-hover: #fdfbf8;
    --text-primary: #3d2e1f;
    --text-secondary: #6b5744;
    --text-muted: #9c8b78;
    --border-color: #ddd0c1;
    --border-hover: #c9b9a5;
    --accent: #c0613a;
    --accent-hover: #a8522f;
    --accent-alt: #4a6e8a;
    --highlight: #c4933e;
    --danger: #b33a3a;
    --success: #5d7e5e;

    --font-heading: 'Sora', sans-serif;
    --font-body: 'Public Sans', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;

    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
    --transition-slow: 0.4s cubic-bezier(0.16, 1, 0.3, 1);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    --shadow-sm: 0 1px 3px rgba(61, 46, 31, 0.06), 0 1px 2px rgba(61, 46, 31, 0.04);
    --shadow-md: 0 4px 12px rgba(61, 46, 31, 0.08), 0 2px 4px rgba(61, 46, 31, 0.04);
    --shadow-lg: 0 12px 32px rgba(61, 46, 31, 0.1), 0 4px 8px rgba(61, 46, 31, 0.06);
    --shadow-xl: 0 20px 48px rgba(61, 46, 31, 0.12), 0 8px 16px rgba(61, 46, 31, 0.06);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: var(--font-body);
    background:
        radial-gradient(ellipse at 15% 10%, rgba(192, 97, 58, 0.04) 0%, transparent 50%),
        radial-gradient(ellipse at 85% 80%, rgba(93, 126, 94, 0.04) 0%, transparent 50%),
        var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.app {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ─── Header ─── */
.header {
    padding: 32px 0 24px;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 24px;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 14px;
}

.logo-icon {
    font-size: 40px;
    filter: drop-shadow(0 2px 8px rgba(192, 97, 58, 0.2));
}

.logo-text h1 {
    font-family: var(--font-heading);
    font-size: 24px;
    font-weight: 700;
    color: var(--text-primary);
    background: linear-gradient(135deg, #3d2e1f 0%, #c0613a 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    font-family: var(--font-body);
    color: var(--text-muted);
    font-size: 13px;
    margin-top: 2px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 16px;
}

.stats {
    display: flex;
    align-items: center;
    gap: 16px;
    background: var(--bg-card);
    padding: 12px 20px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-value {
    font-size: 22px;
    font-weight: 700;
    font-family: var(--font-mono);
    color: var(--text-primary);
}

.stat-label {
    font-size: 11px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-family: var(--font-body);
}

.stat-divider {
    width: 1px;
    height: 36px;
    background: var(--border-color);
}

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

/* ─── Buttons ─── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 18px;
    border-radius: var(--radius-md);
    font-size: 13px;
    font-weight: 500;
    text-decoration: none;
    transition: all var(--transition-fast);
    cursor: pointer;
    border: none;
    font-family: var(--font-body);
}

.btn:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.btn-icon {
    background: var(--bg-card);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    padding: 10px 16px;
    box-shadow: var(--shadow-sm);
}

.btn-icon:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border-color: var(--border-hover);
    box-shadow: var(--shadow-md);
}

.btn-primary {
    background: var(--accent);
    color: #fff;
    font-weight: 600;
}

.btn-primary:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(192, 97, 58, 0.25);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
    background: var(--bg-secondary);
    border-color: var(--border-hover);
}

/* ─── Dropdown ─── */
.dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: calc(100% + 6px);
    right: 0;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 6px;
    min-width: 180px;
    z-index: 100;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-lg);
}

.dropdown.open .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    padding: 10px 14px;
    background: none;
    border: none;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    font-size: 13px;
    font-family: var(--font-body);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.dropdown-item:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.dropdown-item:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}

.dropdown-divider {
    height: 1px;
    background: var(--border-color);
    margin: 4px 6px;
}

/* ─── Category Tabs ─── */
.tabs {
    display: flex;
    gap: 6px;
    padding: 6px;
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: 20px;
    overflow-x: auto;
    scrollbar-width: none;
    box-shadow: var(--shadow-sm);
}

.tabs::-webkit-scrollbar { display: none; }

.tab {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 13px;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    font-family: var(--font-body);
}

.tab:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: -2px;
}

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

.tab.active {
    background: var(--bg-secondary);
    color: var(--text-primary);
    box-shadow: 0 0 0 1px var(--tab-color, var(--border-hover));
}

.tab-icon { font-size: 16px; display: flex; align-items: center; }

.tab-icon svg {
    width: 16px;
    height: 16px;
    stroke: currentColor;
    fill: none;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
}

.tab-count {
    background: var(--border-color);
    padding: 2px 8px;
    border-radius: 20px;
    font-size: 11px;
    font-family: var(--font-mono);
    color: var(--text-secondary);
}

.tab.active .tab-count {
    background: var(--tab-color, var(--accent));
    color: #fff;
}

/* ─── Timeline ─── */
.timeline-section {
    margin-bottom: 20px;
}

.timeline-toggle {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 13px;
    font-family: var(--font-body);
    cursor: pointer;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-sm);
}

.timeline-toggle:hover {
    background: var(--bg-secondary);
    color: var(--text-primary);
}

.timeline-toggle:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.timeline-toggle .chevron {
    transition: transform var(--transition-fast);
}

.timeline-section.open .timeline-toggle .chevron {
    transform: rotate(180deg);
}

.timeline-toggle svg { flex-shrink: 0; }

.timeline-container {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, margin 0.35s ease;
    margin-top: 0;
}

.timeline-section.open .timeline-container {
    max-height: 120px;
    margin-top: 12px;
}

.timeline-track {
    display: flex;
    align-items: flex-end;
    gap: 3px;
    padding: 16px 12px 8px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    overflow-x: auto;
    scrollbar-width: thin;
    scrollbar-color: var(--border-color) transparent;
    box-shadow: var(--shadow-sm);
}

.timeline-bar {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
    cursor: pointer;
    min-width: 24px;
    flex-shrink: 0;
    transition: all var(--transition-fast);
}

.timeline-bar:hover .bar-fill {
    opacity: 1;
}

.timeline-bar.active .bar-fill {
    opacity: 1;
    box-shadow: 0 0 8px rgba(192, 97, 58, 0.3);
}

.bar-fill {
    width: 16px;
    border-radius: 3px 3px 0 0;
    background: var(--accent);
    opacity: 0.35;
    transition: all var(--transition-fast);
    min-height: 2px;
}

.bar-year {
    font-size: 9px;
    font-family: var(--font-mono);
    color: var(--text-muted);
    transform: rotate(-45deg);
    white-space: nowrap;
}

.timeline-bar.active .bar-year {
    color: var(--text-primary);
    font-weight: 600;
}

/* ─── Filter Info ─── */
.filter-info {
    display: none;
    align-items: center;
    gap: 10px;
    padding: 10px 16px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    font-size: 13px;
    color: var(--text-secondary);
    box-shadow: var(--shadow-sm);
}

.filter-info.visible {
    display: flex;
}

.filter-info .clear-filter {
    margin-left: auto;
    padding: 4px 10px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-muted);
    font-size: 12px;
    cursor: pointer;
    font-family: var(--font-body);
    transition: all var(--transition-fast);
}

.filter-info .clear-filter:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
}

/* ─── Bento Grid ─── */
.bento-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 16px;
    padding-bottom: 24px;
}

.paper-card {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 20px 48px 20px 20px;
    cursor: pointer;
    transition: all var(--transition-normal);
    overflow: hidden;
    animation: fadeUp 0.5s cubic-bezier(0.16, 1, 0.3, 1) forwards;
    opacity: 0;
    box-shadow: var(--shadow-sm);
}

.paper-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    width: 3px;
    background: var(--card-color, var(--accent));
    opacity: 0.5;
    transition: opacity var(--transition-fast);
    border-radius: 3px 0 0 3px;
}

.paper-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.paper-card:hover::before {
    opacity: 1;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.card-category {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 4px 10px;
    background: color-mix(in srgb, var(--card-color, var(--accent)) 10%, transparent);
    border-radius: 20px;
    font-size: 11px;
    color: var(--card-color, var(--accent));
    font-weight: 500;
}

.card-category svg {
    width: 12px;
    height: 12px;
}

.card-year {
    font-family: var(--font-mono);
    font-size: 12px;
    color: var(--text-muted);
    background: var(--bg-secondary);
    padding: 3px 8px;
    border-radius: var(--radius-sm);
}

.card-header-right {
    display: flex;
    align-items: center;
    gap: 6px;
}

.card-extra-tags {
    font-family: var(--font-mono);
    font-size: 10px;
    font-weight: 600;
    color: var(--text-muted);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    padding: 2px 6px;
    border-radius: 10px;
    cursor: help;
    transition: all var(--transition-fast);
}
.card-extra-tags:hover {
    color: var(--accent);
    border-color: var(--accent);
}

.card-title {
    font-family: var(--font-heading);
    font-size: 15px;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 8px;
    color: var(--text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-authors {
    font-size: 12px;
    color: var(--text-muted);
    margin-bottom: 10px;
    display: -webkit-box;
    -webkit-line-clamp: 1;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.card-summary {
    font-size: 12px;
    color: var(--text-secondary);
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    margin-bottom: 10px;
}

.card-journal {
    font-size: 11px;
    color: var(--text-muted);
    font-style: italic;
    display: -webkit-box;
    -webkit-line-clamp: 1;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* ─── Load More ─── */
.load-more-container {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 24px 0 40px;
}

.load-more-container.visible {
    display: flex;
}

.load-more-info {
    font-size: 12px;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

/* ─── Modal ─── */
.modal {
    position: fixed;
    inset: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 24px;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

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

.modal-backdrop {
    position: absolute;
    inset: 0;
    background: rgba(61, 46, 31, 0.4);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.modal-content {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-xl);
    padding: 32px;
    max-width: 720px;
    width: 100%;
    max-height: 85vh;
    overflow-y: auto;
    transform: translateY(20px) scale(0.95);
    transition: transform var(--transition-normal);
    box-shadow: var(--shadow-xl);
}

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

.modal-close {
    position: absolute;
    top: 16px;
    right: 16px;
    width: 36px;
    height: 36px;
    border: none;
    background: var(--bg-secondary);
    border-radius: 50%;
    font-size: 22px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

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

.modal-close:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.modal-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 14px;
    flex-wrap: wrap;
}

.modal-category {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 12px;
    font-weight: 500;
}

.modal-extra-categories {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    flex-wrap: wrap;
}

.modal-extra-cat {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 16px;
    font-size: 11px;
    font-weight: 500;
}

.modal-year {
    font-family: var(--font-mono);
    font-size: 13px;
    color: var(--text-muted);
}

.modal-title {
    font-family: var(--font-heading);
    font-size: 22px;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 10px;
    padding-right: 40px;
}

.modal-authors {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 6px;
}

.modal-journal {
    color: var(--text-muted);
    font-size: 13px;
    font-style: italic;
    margin-bottom: 20px;
}

.modal-section {
    margin-bottom: 20px;
}

.modal-section h3 {
    font-family: var(--font-heading);
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.modal-section p {
    font-size: 14px;
    line-height: 1.7;
    color: var(--text-primary);
}

#modal-summary-section p {
    padding: 14px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border-left: 3px solid var(--accent);
}

.modal-actions {
    display: flex;
    gap: 10px;
    padding-top: 8px;
}

.modal-actions .btn { font-size: 13px; }

.modal-actions .btn svg {
    width: 14px;
    height: 14px;
    flex-shrink: 0;
}

/* ─── Paper Selection (Checkbox) ─── */
.card-checkbox {
    position: absolute;
    top: 16px;
    right: 16px;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    border: 2px solid var(--border-hover);
    background: var(--bg-card);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    z-index: 2;
    padding: 0;
    color: transparent;
    font-size: 13px;
    line-height: 1;
}

.card-checkbox:hover {
    border-color: var(--accent);
    background: color-mix(in srgb, var(--accent) 8%, var(--bg-card));
}

.card-checkbox:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 2px;
}

.card-checkbox.checked {
    background: var(--accent);
    border-color: var(--accent);
    color: #fff;
    box-shadow: 0 0 8px rgba(192, 97, 58, 0.3);
}

.paper-card.selected {
    border-color: color-mix(in srgb, var(--accent) 40%, var(--border-color));
    box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 15%, transparent), var(--shadow-md);
}

.selection-count {
    background: var(--accent);
    color: #fff;
    padding: 2px 8px;
    border-radius: 20px;
    font-size: 11px;
    font-family: var(--font-mono);
    font-weight: 600;
    margin-left: 4px;
    display: none;
}

.selection-count.visible {
    display: inline-flex;
}

/* ─── Footer ─── */
.footer {
    position: relative;
    text-align: center;
    padding: 32px 0;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 13px;
}

.footer::before {
    content: '';
    position: absolute;
    top: -1px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 2px;
    background: var(--accent);
    border-radius: 2px;
    opacity: 0.4;
}

.footer-sub {
    font-size: 12px;
    font-family: var(--font-mono);
    margin-top: 4px;
    opacity: 0.7;
}

/* ─── Animations ─── */
@keyframes fadeUp {
    from { opacity: 0; transform: translateY(16px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ─── Accessibility: Reduced Motion ─── */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* ─── Responsive ─── */
@media (max-width: 768px) {
    .app { padding: 0 14px; }
    .header { padding: 20px 0 16px; }
    .header-content { flex-direction: column; align-items: flex-start; gap: 14px; }
    .header-right { width: 100%; justify-content: space-between; }
    .logo-icon { font-size: 32px; }
    .logo-text h1 { font-size: 20px; }
    .stats { padding: 10px 16px; }
    .stat-value { font-size: 18px; }

    .tabs { padding: 4px; gap: 4px; }
    .tab { padding: 10px 12px; font-size: 12px; min-height: 44px; }
    .tab .tab-label { display: none; }
    .tab-icon { font-size: 18px; }

    .bento-grid { grid-template-columns: 1fr; gap: 12px; }
    .paper-card { padding: 16px 44px 16px 16px; }
    .card-title { font-size: 14px; }

    .modal { padding: 0; }
    .modal-content {
        padding: 24px;
        max-height: 100vh;
        height: 100%;
        border-radius: 0;
        border: none;
    }
    .modal-title { font-size: 18px; }
    .modal-actions {
        flex-direction: column;
        position: sticky;
        bottom: 0;
        background: var(--bg-card);
        margin: 0 -24px -24px;
        padding: 14px 24px;
        border-top: 1px solid var(--border-color);
    }
    .btn { justify-content: center; min-height: 44px; }
}

@media (max-width: 480px) {
    .header-actions { gap: 6px; }
    .btn-icon span { display: none; }
    .btn-icon { padding: 10px 12px; }
    .stats { gap: 10px; padding: 8px 14px; }
    .stat-value { font-size: 16px; }
    .tab-count { display: none; }
}

@media (min-width: 1200px) {
    .bento-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 1600px) {
    .bento-grid { grid-template-columns: repeat(4, 1fr); }
}