/* =====================================================
   ABSOLUTE PITCH STUDIES - MODERN CSS
   Created: Dec 2025
   ===================================================== */

/* ===== CSS Variables ===== */
:root {
    /* Colors */
    --primary: #2196f3;
    --primary-dark: #1976d2;
    --secondary: #ff9800;
    --success: #4caf50;
    --warning: #ffc107;
    --danger: #f44336;

    /* Badge Colors */
    --badge-historical: #f0f0f0;
    --badge-recent: #e3f2fd;
    --badge-breakthrough: #c8e6c9;

    /* Text */
    --text-primary: #333;
    --text-secondary: #666;
    --text-muted: #999;

    /* Background */
    --bg-primary: #fff;
    --bg-secondary: #f9f9f9;
    --bg-accent: #fff3e0;

    /* Borders */
    --border-color: #ddd;
    --border-radius: 8px;

    /* Spacing */
    --spacing-xs: 8px;
    --spacing-sm: 12px;
    --spacing-md: 20px;
    --spacing-lg: 32px;
    --spacing-xl: 48px;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.15);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.2);

    /* Transitions */
    --transition: all 0.3s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    color: var(--text-primary);
    background: var(--bg-secondary);
    line-height: 1.6;
    font-size: 16px;
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===== Header & Navigation ===== */
header {
    background: var(--bg-primary);
    border-bottom: 2px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    text-decoration: none;
    transition: var(--transition);
}

.logo:hover {
    color: var(--primary-dark);
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary);
    background: var(--bg-secondary);
}

/* ===== Hero Section ===== */
.hero {
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
}

/* ===== Controls (Search & Filters) ===== */
.controls {
    background: var(--bg-primary);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    margin-bottom: var(--spacing-lg);
}

#search {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: var(--spacing-md);
    transition: var(--transition);
}

#search:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(33, 150, 243, 0.1);
}

.filters {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.filter-btn {
    padding: var(--spacing-xs) var(--spacing-md);
    border: 2px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: 20px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
}

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

.filter-btn.active {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* ===== Section Dividers ===== */
.section-divider {
    border: 0;
    height: 2px;
    background: linear-gradient(to right, transparent, var(--border-color), transparent);
    margin: var(--spacing-xl) 0;
}

/* ===== Studies Section ===== */
.studies-section {
    margin-bottom: var(--spacing-xl);
}

.section-header {
    margin-bottom: var(--spacing-lg);
}

.section-header h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.section-description {
    font-style: italic;
    color: var(--text-secondary);
    max-width: 900px;
}

/* ===== Studies Grid ===== */
.studies-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

/* ===== Study Card ===== */
.study-card {
    background: var(--bg-primary);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    border: 2px solid transparent;
}

.study-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary);
}

.study-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.study-badge {
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.study-badge.historical {
    background: var(--badge-historical);
    color: var(--text-secondary);
}

.study-badge.recent {
    background: var(--badge-recent);
    color: var(--primary);
}

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

.study-year {
    font-weight: 700;
    color: var(--text-muted);
}

.study-card h3 {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
    line-height: 1.4;
}

.study-meta {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: var(--spacing-sm);
}

.study-summary {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    flex-grow: 1;
    line-height: 1.6;
}

.study-summary strong {
    color: var(--text-primary);
}

.study-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: auto;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

.study-score {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 600;
}

.study-score.perfect {
    color: var(--success);
}

/* ===== Buttons ===== */
.btn-primary {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--primary);
    color: white;
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 500;
    transition: var(--transition);
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateX(2px);
}

/* ===== Timeline Section ===== */
.timeline-section {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
}

.timeline-section h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.timeline {
    max-width: 800px;
    margin: 0 auto var(--spacing-lg);
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 80px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(to bottom, var(--primary), var(--success));
}

.timeline-item {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    position: relative;
}

.timeline-year {
    width: 80px;
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--primary);
    text-align: right;
    flex-shrink: 0;
}

.timeline-content {
    background: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary);
    flex-grow: 1;
    position: relative;
}

.timeline-content::before {
    content: '';
    position: absolute;
    left: -15px;
    top: 50%;
    transform: translateY(-50%);
    width: 12px;
    height: 12px;
    background: var(--primary);
    border-radius: 50%;
    border: 3px solid var(--bg-primary);
}

/* ===== Insight Box ===== */
.insight-box {
    background: var(--bg-accent);
    border-left: 4px solid var(--secondary);
    padding: var(--spacing-md);
    border-radius: var(--border-radius);
    margin-top: var(--spacing-lg);
}

.insight-box strong {
    color: var(--text-primary);
}

/* ===== Footer ===== */
footer {
    background: var(--text-primary);
    color: white;
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-xl);
}

footer a {
    color: var(--primary);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

footer p {
    margin-bottom: var(--spacing-sm);
    text-align: center;
}

.footer-note {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.8rem;
    }

    .subtitle {
        font-size: 1rem;
    }

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

    .nav-links {
        gap: var(--spacing-md);
    }

    .section-header h2 {
        font-size: 1.5rem;
    }

    .timeline::before {
        left: 60px;
    }

    .timeline-year {
        width: 60px;
        font-size: 1rem;
    }

    .filters {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.5rem;
    }

    .study-card {
        padding: var(--spacing-md);
    }

    .study-footer {
        flex-direction: column;
        gap: var(--spacing-sm);
        align-items: flex-start;
    }

    nav {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .nav-links {
        width: 100%;
        justify-content: space-around;
    }
}

/* ===== Utility Classes ===== */
.hidden {
    display: none !important;
}

.text-center {
    text-align: center;
}

.mt-lg {
    margin-top: var(--spacing-lg);
}

.mb-lg {
    margin-bottom: var(--spacing-lg);
}

/* ===== Print Styles ===== */
@media print {
    header, footer, .controls {
        display: none;
    }

    .study-card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid var(--border-color);
    }
}