:root {
    --color-primary: #0056A0;
    --color-accent: #00A1E4;
    --color-secondary: #3C78C8;
    --color-light: #86CFF2;
    --color-bg: #f0f4f8;
    --color-text: #1a202c;
    --color-text-muted: #64748b;
    --color-white: #FFFFFF;
    --color-border: #e2e8f0;
    --color-row-even: #f8fafc;
    --color-row-selected: #dbeafe;
    --color-brand: #ffffff;
}

/* Dark mode */
[data-theme="dark"] {
    --color-primary: #60a5fa;
    --color-accent: #38bdf8;
    --color-secondary: #1e40af;
    --color-light: #1e3a5f;
    --color-bg: #0f172a;
    --color-text: #e2e8f0;
    --color-text-muted: #94a3b8;
    --color-white: #1e293b;
    --color-border: #334155;
    --color-row-even: #1e293b;
    --color-row-selected: #1e3a5f;
    --color-brand: #f97316;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--color-bg);
    color: var(--color-text);
}

.header-bg { background-color: #0056A0; }
[data-theme="dark"] .header-bg { background-color: #1e293b; }

.header-text { color: #FFFFFF; }
.card-bg { background-color: var(--color-white); }
.primary-text { color: var(--color-primary); }
.accent-bg { background-color: var(--color-accent); }
.accent-text { color: var(--color-accent); }
.muted-text { color: var(--color-text-muted); }

/* Site name / brand */
.site-name {
    color: var(--color-brand);
    letter-spacing: -0.02em;
}

/* Screen reader only */
.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;
}

/* Skip to content */
.skip-link {
    position: absolute;
    top: -100%;
    left: 16px;
    z-index: 100;
    padding: 10px 20px;
    background: var(--color-primary);
    color: #fff;
    font-weight: 700;
    border-radius: 0 0 8px 8px;
    text-decoration: none;
    transition: top 0.2s;
}

.skip-link:focus {
    top: 0;
}

/* Global focus-visible */
:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

[data-theme="dark"] :focus-visible {
    outline-color: #60a5fa;
}

.theme-toggle {
    background: rgba(255, 255, 255, 0.15);
    border: none;
    border-radius: 8px;
    min-width: 44px;
    min-height: 44px;
    padding: 8px 12px;
    cursor: pointer;
    font-size: 1.2rem;
    line-height: 1;
    transition: background 0.2s;
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.25);
}

.theme-toggle:focus-visible {
    outline-color: #fff;
}

/* Search input */
.search-input {
    background-color: var(--color-white);
    color: var(--color-text);
    border: 2px solid var(--color-border);
    border-radius: 8px;
    padding: 10px 14px 10px 38px;
    font-size: 0.95rem;
    width: 100%;
    max-width: 360px;
    transition: border-color 0.2s;
}

.search-input:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: -2px;
    border-color: var(--color-primary);
}

.search-wrapper {
    position: relative;
    display: inline-block;
    width: 100%;
    max-width: 360px;
}

.search-icon {
    position: absolute;
    left: 12px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-muted);
    font-size: 0.9rem;
    pointer-events: none;
}

/* Filter chips */
.filter-chip {
    display: inline-block;
    padding: 8px 16px;
    min-height: 38px;
    border-radius: 9999px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    border: 2px solid var(--color-border);
    background-color: var(--color-white);
    color: var(--color-text);
    transition: all 0.15s;
    user-select: none;
}

.filter-chip:hover {
    border-color: var(--color-primary);
}

.filter-chip.active {
    background-color: var(--color-primary);
    border-color: var(--color-primary);
    color: #FFFFFF;
}

/* Charts */
.chart-container {
    position: relative;
    width: 100%;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    height: 400px;
    max-height: 450px;
}

@media (min-width: 768px) {
    .chart-container { height: 450px; }
}

/* Table */
table th {
    background-color: #3C78C8;
    color: white;
    padding: 12px 16px;
    text-align: left;
    white-space: nowrap;
}

[data-theme="dark"] table th {
    background-color: #1e40af;
}

table th.sortable {
    cursor: pointer;
    user-select: none;
    transition: background-color 0.15s;
}

table th.sortable:hover,
table th.sortable:focus-visible {
    background-color: #0056A0;
}

table th.sortable:focus-visible {
    outline: 2px solid #fff;
    outline-offset: -2px;
}

[data-theme="dark"] table th.sortable:hover {
    background-color: #1d4ed8;
}

table th .sort-icon {
    margin-left: 4px;
    opacity: 0.4;
    font-size: 0.7rem;
}

table th.sort-asc .sort-icon,
table th.sort-desc .sort-icon {
    opacity: 1;
}

table td {
    padding: 12px 16px;
    border-bottom: 1px solid var(--color-border);
}

table tr:nth-child(even) {
    background-color: var(--color-row-even);
}

table tr.selected {
    background-color: var(--color-row-selected) !important;
}

table tr.filtered-out {
    opacity: 0.25;
}

/* Table scroll hint */
.table-scroll-wrapper {
    position: relative;
    overflow: hidden;
}

.table-scroll-wrapper .overflow-x-auto {
    scrollbar-width: thin;
}

.table-scroll-wrapper::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    width: 40px;
    background: linear-gradient(to right, transparent, var(--color-white));
    pointer-events: none;
    transition: opacity 0.3s;
    z-index: 1;
}

.table-scroll-wrapper.scrolled-end::after {
    opacity: 0;
}

.scroll-hint {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    transition: opacity 0.3s;
}

.scroll-hint-icon {
    animation: scroll-hint-bounce 1.5s ease-in-out infinite;
}

@keyframes scroll-hint-bounce {
    0%, 100% { transform: translateX(0); }
    50% { transform: translateX(5px); }
}

/* Material name link */
a.mat-link {
    color: var(--color-primary);
    text-decoration: none;
    font-weight: 600;
}

a.mat-link:hover {
    text-decoration: underline;
}

/* Property tags */
.tag {
    display: inline-block;
    padding: 4px 12px;
    border-radius: 9999px;
    font-weight: 600;
    font-size: 0.875rem;
}

.tag-vlow    { background-color: #fecaca; color: #991b1b; }
.tag-low     { background-color: #fee2e2; color: #b91c1c; }
.tag-med     { background-color: #fef3c7; color: #b45309; }
.tag-high    { background-color: #d1fae5; color: #065f46; }
.tag-vhigh   { background-color: #cceeff; color: #0369a1; }
.tag-special { background-color: #e0e7ff; color: #3730a3; }
.tag-soluble { background-color: #f0abfc; color: #701a75; }

[data-theme="dark"] .tag-vlow    { background-color: #450a0a; color: #fca5a5; }
[data-theme="dark"] .tag-low     { background-color: #7f1d1d; color: #fecaca; }
[data-theme="dark"] .tag-med     { background-color: #78350f; color: #fde68a; }
[data-theme="dark"] .tag-high    { background-color: #064e3b; color: #a7f3d0; }
[data-theme="dark"] .tag-vhigh   { background-color: #0c4a6e; color: #bae6fd; }
[data-theme="dark"] .tag-special { background-color: #312e81; color: #c7d2fe; }
[data-theme="dark"] .tag-soluble { background-color: #701a75; color: #f0abfc; }

/* Language switcher */
.lang-switcher a {
    padding: 8px 14px;
    min-width: 44px;
    min-height: 44px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.875rem;
}

.lang-switcher a.active {
    background-color: #FFFFFF;
    color: #0056A0;
}

.lang-switcher a:not(.active) {
    color: rgba(255, 255, 255, 0.7);
}

.lang-switcher a:not(.active):hover {
    color: #FFFFFF;
}

/* Export section border */
.export-card {
    border: 2px solid var(--color-primary);
}

/* Detail page */
.detail-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
}

.detail-prop {
    padding: 12px;
    border-radius: 8px;
    background-color: var(--color-row-even);
    border: 1px solid var(--color-border);
}

.detail-prop-label {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 4px;
}

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

.detail-list li {
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
    border-bottom: 1px solid var(--color-border);
}

.detail-list li:last-child {
    border-bottom: none;
}

.detail-list li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 12px;
    width: 8px;
    height: 8px;
    border-radius: 50%;
}

.detail-list.pros li::before { background-color: #10b981; }
.detail-list.cons li::before { background-color: #ef4444; }
.detail-list.uses li::before { background-color: var(--color-primary); }

/* Site navigation bar */
.site-nav {
    background-color: #003d73;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

[data-theme="dark"] .site-nav {
    background-color: #0f172a;
    border-bottom: 1px solid #334155;
}

.site-nav-link {
    display: inline-flex;
    align-items: center;
    padding: 12px 20px;
    color: rgba(255, 255, 255, 0.75);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: background 0.15s, color 0.15s;
}

.site-nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
    color: #fff;
}

.site-nav-link.active {
    background: rgba(255, 255, 255, 0.15);
    color: #fff;
    box-shadow: inset 0 -3px 0 #00A1E4;
}

[data-theme="dark"] .site-nav-link.active {
    box-shadow: inset 0 -3px 0 #38bdf8;
}

/* Troubleshooting page */
.ts-card {
    cursor: pointer;
    transition: box-shadow 0.2s, transform 0.15s;
}

.ts-card:hover {
    box-shadow: 0 8px 25px rgba(0,0,0,0.12);
    transform: translateY(-2px);
}

.ts-card.open {
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
}

.ts-detail {
    display: none;
    border-top: 1px solid var(--color-border);
    margin-top: 16px;
    padding-top: 16px;
}

.ts-card.open .ts-detail {
    display: block;
}

.ts-svg {
    width: 100%;
    max-width: 220px;
    height: 140px;
    margin: 0 auto 12px;
    display: block;
}

.ts-step {
    transition: opacity 0.3s, max-height 0.4s;
    overflow: hidden;
}

.ts-step.hidden {
    opacity: 0;
    max-height: 0;
    padding: 0;
    margin: 0;
}

.ts-option-btn {
    display: block;
    width: 100%;
    text-align: left;
    padding: 14px 18px;
    margin-bottom: 8px;
    border: 2px solid var(--color-border);
    border-radius: 10px;
    background-color: var(--color-white);
    color: var(--color-text);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: border-color 0.15s, background 0.15s;
}

.ts-option-btn:hover {
    border-color: var(--color-primary);
    background-color: var(--color-row-even);
}

.ts-option-btn.selected {
    border-color: var(--color-primary);
    background-color: var(--color-row-selected);
}

.ts-solution-step {
    padding: 8px 0 8px 28px;
    position: relative;
    border-bottom: 1px solid var(--color-border);
}

.ts-solution-step:last-child {
    border-bottom: none;
}

.ts-solution-step::before {
    content: attr(data-step);
    position: absolute;
    left: 0;
    top: 8px;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background-color: var(--color-primary);
    color: #fff;
    font-size: 0.75rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Hero cards on homepage */
.hero-feature-card {
    transition: transform 0.2s, box-shadow 0.2s;
}

.hero-feature-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 30px rgba(0,0,0,0.12);
}

/* Ad slots */
.ad-slot {
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 2rem 0;
    min-height: 90px;
    overflow: hidden;
}

.ad-slot ins {
    display: block;
    width: 100%;
}

/* Guide inline tables */
.guide-table {
    width: 100%;
    font-size: 0.875rem;
    margin-top: 0.5rem;
    border-collapse: collapse;
}

.guide-table th {
    background-color: var(--color-row-even);
    color: var(--color-text);
    padding: 10px 12px;
    text-align: left;
    font-weight: 600;
    border-bottom: 2px solid var(--color-border);
    white-space: normal;
}

.guide-table td {
    padding: 10px 12px;
    border-bottom: 1px solid var(--color-border);
    color: var(--color-text);
}

.guide-table tr:nth-child(even) td {
    background-color: var(--color-row-even);
}

.guide-table tr:hover td {
    background-color: var(--color-row-selected);
}