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

:root {
    --primary: #2563eb;
    --primary-dark: #1e40af;
    --secondary: #8b5cf6;
    --background: #0f172a;
    --surface: #1e293b;
    --surface-light: #334155;
    --text: #f1f5f9;
    --text-secondary: #cbd5e1;
    --accent: #06b6d4;
    --success: #10b981;
    --warning: #f59e0b;
    --border: #475569;
    --shadow: rgba(0, 0, 0, 0.3);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--background) 0%, #1a1f3a 100%);
    color: var(--text);
    min-height: 100vh;
    line-height: 1.6;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

header {
    text-align: center;
    margin-bottom: 3rem;
    padding: 2rem 0;
}

header h1 {
    font-size: 3rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
    font-weight: 700;
    letter-spacing: -1px;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
    font-weight: 300;
}

.category-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 2rem;
}

.category-btn {
    padding: 0.75rem 1.5rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 50px;
    color: var(--text);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.category-btn::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: var(--primary);
    transform: translate(-50%, -50%);
    transition: width 0.4s ease, height 0.4s ease;
    z-index: -1;
}

.category-btn:hover::before {
    width: 300px;
    height: 300px;
}

.category-btn:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
    box-shadow: 0 4px 20px rgba(37, 99, 235, 0.3);
}

.category-btn.active {
    background: var(--primary);
    border-color: var(--primary);
    color: white;
    box-shadow: 0 4px 20px rgba(37, 99, 235, 0.4);
}

.search-container {
    margin-bottom: 2rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.search-input {
    width: 100%;
    padding: 1rem 1.5rem;
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 50px;
    color: var(--text);
    font-size: 1rem;
    transition: all 0.3s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.search-input::placeholder {
    color: var(--text-secondary);
}

.systems-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.system-card {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 16px;
    padding: 2rem;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.system-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.system-card:hover::before {
    transform: scaleX(1);
}

.system-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
    box-shadow: 0 10px 40px var(--shadow);
}

.system-category {
    display: inline-block;
    padding: 0.35rem 1rem;
    background: var(--surface-light);
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 1rem;
}

.system-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text);
}

.system-description {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.system-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.tag {
    padding: 0.25rem 0.75rem;
    background: rgba(37, 99, 235, 0.1);
    border: 1px solid rgba(37, 99, 235, 0.3);
    border-radius: 50px;
    font-size: 0.8rem;
    color: var(--accent);
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
    z-index: 1000;
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.modal-content {
    background: var(--surface);
    border: 2px solid var(--border);
    border-radius: 20px;
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    animation: slideUp 0.3s ease;
    padding: 3rem;
}

@keyframes slideUp {
    from {
        transform: translateY(50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-close {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    background: var(--surface-light);
    border: none;
    color: var(--text);
    font-size: 2rem;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-close:hover {
    background: var(--primary);
    transform: rotate(90deg);
}

.modal-header {
    margin-bottom: 2rem;
}

.modal-title {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.detail-section {
    margin-bottom: 2rem;
}

.detail-section h4 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--accent);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.detail-section h4::before {
    content: '';
    width: 4px;
    height: 24px;
    background: var(--primary);
    border-radius: 2px;
}

.detail-section p,
.detail-section ul {
    color: var(--text-secondary);
    line-height: 1.8;
}

.detail-section ul {
    list-style: none;
    padding-left: 0;
}

.detail-section li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.detail-section li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--primary);
    font-weight: bold;
}

.example-box {
    background: var(--background);
    border-left: 4px solid var(--primary);
    padding: 1.5rem;
    border-radius: 8px;
    margin-top: 1rem;
}

.example-box strong {
    color: var(--accent);
}

/* Scrollbar Styles */
::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--background);
}

::-webkit-scrollbar-thumb {
    background: var(--surface-light);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    header h1 {
        font-size: 2rem;
    }

    .systems-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .category-nav {
        gap: 0.5rem;
    }

    .category-btn {
        padding: 0.5rem 1rem;
        font-size: 0.85rem;
    }

    .modal-content {
        padding: 2rem;
    }

    .modal-title {
        font-size: 1.8rem;
    }
}