:root {
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #3498db;
    --text-color: #333;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    --font-family: 'Inter', sans-serif;
}

body {
    font-family: var(--font-family);
    color: var(--text-color);
    background-color: var(--light-bg);
}

.navbar {
    background-color: var(--white);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.hero-section {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    padding: 80px 0;
    text-align: center;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--secondary-color);
    margin-bottom: 40px;
}

/* ── Mobile responsive ── */
@media (max-width: 767.98px) {
    .hero-section {
        padding: 40px 0;
    }
    .hero-title {
        font-size: 1.75rem;
        margin-bottom: 12px;
    }
    .hero-subtitle {
        font-size: 1rem;
        margin-bottom: 24px;
    }
    .hero-logo {
        display: none;
    }
    .article-list-pdf {
        text-align: left !important;
        margin-top: 8px;
    }
}

.search-card {
    background: var(--white);
    padding: 30px;
    border-radius: 15px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    max-width: 800px;
    margin: 0 auto;
}

.article-card {
    background: var(--white);
    border: none;
    border-radius: 10px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    height: 100%;
    overflow: hidden;
}

.article-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.1);
}

.article-badge {
    position: absolute;
    top: 15px;
    right: 15px;
    padding: 5px 10px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.badge-clinical { background-color: #e1f5fe; color: #0288d1; }
.badge-community { background-color: #e8f5e9; color: #388e3c; }
.badge-addiction { background-color: #fff3e0; color: #f57c00; }
.badge-child { background-color: #f3e5f5; color: #7b1fa2; }

.card-body {
    padding: 25px;
}

.card-title a {
    color: var(--primary-color);
    font-weight: 700;
    text-decoration: none;
    transition: color 0.2s;
}

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

.card-meta {
    font-size: 0.9rem;
    color: #7f8c8d;
    margin-bottom: 15px;
}

.btn-primary {
    background-color: var(--accent-color);
    border-color: var(--accent-color);
    padding: 10px 25px;
    font-weight: 600;
    border-radius: 5px;
    transition: background-color 0.3s;
}

.btn-primary:hover {
    background-color: #2980b9;
    border-color: #2980b9;
}

.footer {
    background-color: var(--white);
    padding: 40px 0;
    margin-top: 60px;
    border-top: 1px solid #eee;
}