:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --bg: #f8fafc;
    --text: #1e293b;
    --card-bg: #ffffff;
    --border: #e2e8f0;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg);
    color: var(--text);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Navbar */
.navbar {
    background: #ffffff;
    border-bottom: 1px solid var(--border);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

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

.nav-links {
    display: flex;
    gap: 1.5rem;
    list-style: none;
    align-items: center;
}

.nav-links a {
    text-decoration: none;
    color: var(--text);
    font-weight: 500;
}

.nav-links a:hover {
    color: var(--primary);
}

/* Responsive Container */
.container {
    width: 90%;
    max-width: 1200px;
    margin: 2rem auto;
    flex: 1;
}

/* Buttons & Inputs */
.btn {
    background: var(--primary);
    color: #fff;
    padding: 0.6rem 1.2rem;
    border-radius: 6px;
    border: none;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    font-size: 0.95rem;
}

.btn:hover {
    background: var(--primary-hover);
}

.form-group {
    margin-bottom: 1.2rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.4rem;
    font-weight: 600;
}

.form-group input, .form-group select, .form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 1rem;
}

/* Ebook Grid */
.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1.8rem;
    margin-top: 1.5rem;
}

.book-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 10px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.05);
}

.book-card img {
    width: 100%;
    height: 280px;
    object-fit: cover;
}

.book-card-body {
    padding: 1.2rem;
    display: flex;
    flex-direction: column;
    flex: 1;
}

.lang-badge {
    background: #e0e7ff;
    color: var(--primary);
    padding: 0.2rem 0.6rem;
    font-size: 0.8rem;
    border-radius: 20px;
    align-self: flex-start;
    margin-bottom: 0.5rem;
}

/* Reader View */
.reader-container {
    background: #fff;
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.audio-controls {
    background: #f1f5f9;
    padding: 1.5rem;
    border-radius: 8px;
    margin-bottom: 2rem;
}

/* Footer */
footer {
    background: #0f172a;
    color: #cbd5e1;
    text-align: center;
    padding: 1.5rem;
    margin-top: 3rem;
}

@media (max-width: 768px) {
    .navbar { flex-direction: column; gap: 1rem; text-align: center; }
    .nav-links { flex-direction: column; gap: 0.8rem; }
}