:root {
    --primary-bg: #0f172a;
    --secondary-bg: #1e293b;
    --accent-gold: #fbbf24;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-blur: blur(12px);
    --shadow-premium: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    --font-main: 'Inter', system-ui, -apple-system, sans-serif;
}

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

body {
    background-color: var(--primary-bg);
    color: var(--text-primary);
    font-family: var(--font-main);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

/* Glassmorphism utility */
.glass-effect {
    background: var(--glass-bg);
    backdrop-filter: var(--glass-blur);
    border: 1px solid var(--glass-border);
    transition: all 0.3s ease;
}

/* Login Page Styles */
.login-container {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: radial-gradient(circle at top left, #1e293b 0%, #0f172a 100%);
    position: relative;
}

.login-card {
    width: 100%;
    max-width: 400px;
    padding: 2.5rem;
    border-radius: 1.5rem;
    box-shadow: var(--shadow-premium);
}

/* Navigation & Search */
.search-box {
    display: flex;
    align-items: center;
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--glass-border);
    border-radius: 0.75rem;
    padding: 0.25rem 0.5rem;
    width: 300px;
}

.search-box input {
    background: none;
    border: none;
    color: white;
    padding: 0.5rem;
    width: 100%;
    font-size: 0.875rem;
}

.search-box input:focus {
    outline: none;
}

.search-box button {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

.alphabet-row {
    margin: 0 2rem 1.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 1rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    align-items: center;
}

.alphabet-row a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.8125rem;
    font-weight: 600;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 5px;
    transition: all 0.2s ease;
}

.alphabet-row a:hover,
.alphabet-row a.active {
    background: var(--accent-gold);
    color: #0f172a;
}

.logo-section {
    text-align: center;
    margin-bottom: 2.5rem;
}

.logo-placeholder {
    width: 80px;
    height: 80px;
    margin: 0 auto 1rem;
    background: linear-gradient(135deg, var(--accent-gold), #d97706);
    border-radius: 20%;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 0 20px rgba(251, 191, 36, 0.3);
}

.library-title {
    font-size: 1.75rem;
    font-weight: 800;
    letter-spacing: -0.025em;
    color: var(--accent-gold);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.login-form .input-group {
    margin-bottom: 1.5rem;
}

.login-form label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.login-form input {
    width: 100%;
    padding: 0.75rem 1rem;
    background: rgba(15, 23, 42, 0.6);
    border: 1px solid var(--glass-border);
    border-radius: 0.75rem;
    color: white;
    font-size: 1rem;
    transition: all 0.2s ease;
}

.login-form input:focus {
    outline: none;
    border-color: var(--accent-gold);
    box-shadow: 0 0 0 2px rgba(251, 191, 36, 0.1);
}

.btn-login {
    width: 100%;
    padding: 0.75rem;
    background: var(--accent-gold);
    color: #0f172a;
    border: none;
    border-radius: 0.75rem;
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    margin-top: 1rem;
}

.btn-login:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(251, 191, 36, 0.4);
}

.btn-login:active {
    transform: translateY(0);
}

.author-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 1.5rem;
}

.author-card {
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 1.5rem;
    border-radius: 1rem;
    text-align: center;
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

.author-card:hover {
    transform: translateY(-5px);
    border-color: var(--accent-gold);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4);
}

.author-card h4 {
    color: var(--accent-gold);
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.author-card .count {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
}

.error-msg {
    color: #ef4444;
    background: rgba(239, 68, 68, 0.1);
    padding: 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.875rem;
    margin-bottom: 1.5rem;
    border: 1px solid rgba(239, 68, 68, 0.2);
}

.book-card {
    border-radius: 1rem;
    padding: 1rem;
    text-align: center;
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5);
}

/* Modal Styling */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(15, 23, 42, 0.8);
    backdrop-filter: blur(8px);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 2rem;
}

.modal-content {
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    border-radius: 2rem;
    padding: 2.5rem;
    position: relative;
    overflow-y: auto;
}

.close-modal {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    line-height: 1;
}

.book-details-layout {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 2.5rem;
}

.modal-cover {
    width: 100%;
    border-radius: 1rem;
    box-shadow: var(--shadow-premium);
}

.book-info h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    line-height: 1.2;
}

.book-info .author {
    font-size: 1.25rem;
    color: var(--accent-gold);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

.metadata-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.metadata-item label {
    display: block;
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.25rem;
}

.description-box {
    background: rgba(255, 255, 255, 0.03);
    padding: 1.5rem;
    border-radius: 1rem;
    margin-bottom: 2rem;
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.action-buttons {
    display: flex;
    gap: 1rem;
}

.btn-action {
    flex: 1;
    padding: 0.875rem;
    border-radius: 0.75rem;
    font-weight: 700;
    text-align: center;
    text-decoration: none;
    transition: all 0.2s ease;
    cursor: pointer;
    border: none;
}

.btn-view {
    background: var(--accent-gold);
    color: #0f172a;
}

.btn-download {
    background: rgba(255, 255, 255, 0.1);
    color: white;
    border: 1px solid var(--glass-border);
}

.btn-action:hover {
    transform: translateY(-2px);
    opacity: 0.9;
}

@media (max-width: 640px) {
    .book-details-layout {
        grid-template-columns: 1fr;
    }

    .modal-cover {
        max-width: 200px;
        margin: 0 auto;
    }
}