:root {
    --primary-color: #4a6fa5;
    --secondary-color: #6c63ff;
    --text-color: #2d3748;
    --bg-color: #f0f2f5;
    --card-bg: rgba(255, 255, 255, 0.7);
    --transition: all 0.3s ease;
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    --border-radius: 12px;
}

/* Dark theme variables */
[data-theme="dark"] {
    --primary-color: #6c63ff;
    --secondary-color: #8a85ff;
    --text-color: #e2e8f0;
    --bg-color: #1a202c;
    --card-bg: rgba(45, 55, 72, 0.7);
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

/* Base styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    background-image: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    transition: var(--transition);
    min-height: 100vh;
}

[data-theme="dark"] body {
    background-image: linear-gradient(135deg, #1a202c 0%, #2d3748 100%);
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
}

/* Glass effect */
.glass {
    background: var(--card-bg);
    backdrop-filter: blur(50px);
    border: 1px solid rgba(255, 255, 255, 0);
    background-color: rgba(60, 60, 60, 0.5);
    box-shadow: var(--shadow);
    border-radius: var(--border-radius);
}

/* Remove glass effect from header */
header.glass {
    background-color: rgba(60, 60, 60, 0.5);
    border: none;
    box-shadow: none;
    backdrop-filter: blur(5px);
}

/* Header styles */
header {
    text-align: center;
    padding: 3rem 0;
    margin-bottom: 2rem;
    background: transparent;
    border-radius: 0 0 30px 30px;
    border: none;
    box-shadow: none;
}

h1 {
    font-size: 2.8rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 1.2rem;
    color: var(--text-color);
    opacity: 0.9;
    margin-bottom: 2rem;
}

/* Search bar */
.search-container {
    display: flex;
    max-width: 600px;
    margin: 0 auto;
    gap: 10px;
}

#searchInput {
    flex: 1;
    padding: 12px 20px;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    color: var(--text-color);
    transition: var(--transition);
}

#searchInput:focus {
    outline: none;
    box-shadow: 0 0 0 2px var(--primary-color);
}

#searchBtn {
    padding: 0 25px;
    border: none;
    border-radius: var(--border-radius);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    cursor: pointer;
    transition: var(--transition);
}

#searchBtn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(108, 99, 255, 0.4);
}

/* Categories */
.categories {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 2rem;
    justify-content: center;
}

.category-btn {
    padding: 8px 20px;
    border: none;
    border-radius: 20px;
    background: var(--card-bg);
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.9rem;
}

.category-btn:hover, .category-btn.active {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    transform: translateY(-2px);
}

/* Knowledge cards grid */
.knowledge-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.knowledge-card {
    padding: 1.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    height: 100%;
    display: flex;
    flex-direction: column;
}

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

.knowledge-card h3 {
    margin-bottom: 0.8rem;
    color: var(--primary-color);
    font-size: 1.2rem;
}

.knowledge-card p {
    margin-bottom: 1rem;
    color: var(--text-color);
    opacity: 0.9;
    flex-grow: 1;
}

.knowledge-card .category {
    display: inline-block;
    padding: 3px 10px;
    border-radius: 15px;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 1rem;
    background: rgba(108, 99, 255, 0.1);
    color: var(--primary-color);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0;
    margin-top: 3rem;
    font-size: 0.9rem;
    color: var(--text-color);
    opacity: 0.8;
}

/* Theme toggle removed - using system preference */

/* Responsive design */
@media (max-width: 768px) {
    h1 {
        font-size: 2.2rem;
    }
    
    .subtitle {
        font-size: 1rem;
    }
    
    .search-container {
        flex-direction: column;
    }
    
    #searchBtn {
        padding: 12px;
    }
    
    .knowledge-grid {
        grid-template-columns: 1fr;
    }
    
    .categories {
        justify-content: flex-start;
        overflow-x: auto;
        padding-bottom: 10px;
        -webkit-overflow-scrolling: touch;
    }
    
    .category-btn {
        white-space: nowrap;
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.animate-fade-in {
    animation: fadeIn 0.6s ease-out forwards;
    opacity: 0;
}