:root {
    /* Core neutral palette */
    --color-ink: #1a1a1a;           /* FIXED: about.css wrongly had #f5f5f5 */
    --color-charcoal: #2d2d2d;
    --color-slate: #4a4a4a;
    --color-grey: #6b6b6b;
    --color-ash: #9a9a9a;
    --color-silver: #d4d4d4;
    --color-pearl: #ebebeb;
    --color-paper: #f8f8f7;
    --color-cream: #fdfcfb;

    /* Accent colours */
    --color-terra: #8b7355;
    --color-terra-light: #a89f91;
    --color-terra-dark: #6b5642;
    --color-warm-grey: var(--color-terra-light); /* alias used by source/explore_sources */
    --color-amber: #b8956a;
    --color-teal: #026d70;
    --color-teal-light: #01999e;
    --color-teal-dark: #014547;
    --color-teal-fade: #02dde4;

    /* Semantic colours */
    --color-primary: var(--color-teal);
    --color-primary-hover: var(--color-teal-dark);
    --color-text: var(--color-charcoal);
    --color-text-muted: var(--color-grey);
    --color-border: var(--color-silver);       /* STANDARDISED to #d4d4d4 */
    --color-border-light: var(--color-pearl);
    --color-bg: var(--color-paper);            /* STANDARDISED: replaces #f0f0f0 / cream */
    --color-surface: #ffffff;
    --color-hover: #f5f5f5;
    --color-active: #e8e8e8;

    /* Status / feedback colours (used in profile.css status badges and alerts) */
    --color-danger: #dc3545;
    --color-neutral: #6c757d;
    --color-neutral-dark: #545b62;
    --color-success-bg: #d4edda;
    --color-success-text: #155724;
    --color-success-border: #c3e6cb;
    --color-warning-bg: #fff3cd;
    --color-warning-text: #856404;
    --color-warning-border: #ffeaa7;
    --color-info-bg: #d1ecf1;
    --color-info-text: #0c5460;
    --color-info-border: #bee5eb;
    --color-error-bg: #f8d7da;
    --color-error-text: #721c24;
    --color-error-border: #f5c6cb;

    /* Typography */
    --font-serif: 'Crimson Text', 'Georgia', 'Times New Roman', serif;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'SF Mono', 'Consolas', 'Monaco', monospace;

    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;

    /* Border radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.04), 0 1px 4px rgba(0,0,0,0.04);
    --shadow-md: 0 2px 4px rgba(0,0,0,0.06), 0 4px 12px rgba(0,0,0,0.08);
    --shadow-lg: 0 4px 8px rgba(0,0,0,0.08), 0 8px 24px rgba(0,0,0,0.12);
    --shadow-hover: 0 8px 16px rgba(0,0,0,0.1), 0 12px 32px rgba(0,0,0,0.15);

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after {
    box-sizing: border-box;
}

.container {
    padding: var(--space-xl);
}

/* ============================================
   Filter Component
   ============================================ */

.filters {
    background: var(--color-surface);
    padding: var(--space-2xl);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    margin-bottom: var(--space-2xl);
    box-shadow: var(--shadow-sm);
}

.filter-section-title {
    width: 100%;
    font-family: var(--font-serif);
    font-size: 1.3em;
    font-weight: 600;
    color: var(--color-ink);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 2px solid var(--color-border-light);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.filters-row {
    display: flex;
    gap: var(--space-lg);
    flex-wrap: wrap;
    align-items: flex-start;
    margin-bottom: var(--space-lg);
}

.filters-row:last-child {
    margin-bottom: 0;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
    flex: 1;
    min-width: 200px;
}

.filter-group label {
    font-weight: 600;
    font-size: 0.875em;
    color: var(--color-slate);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

@media (max-width: 768px) {
    .filters {
        padding: var(--space-lg);
    }

    .filters-row {
        flex-direction: column;
    }

    .filter-group {
        width: 100%;
    }
}