* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

body {
    background: #fefefe;
    color: #333;
}

/* Navbar */
.navbar {
    background: #800000;
    color: #fff;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 30px;
}
.navbar ul {
    display: flex;
    list-style: none;
}
.navbar ul li a {
    color: white;
    text-decoration: none;
    margin: 0 10px;
    font-weight: 500;
}
.navbar ul li a:hover {
    text-decoration: underline;
}

/* Banner */
.banner {
    height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-shadow: 2px 2px 5px black;
    font-size: 28px;
}

/* Search */
.search-bar {
    text-align: center;
    margin: 20px;
}
.search-bar input {
    padding: 10px;
    width: 250px;
    border-radius: 8px;
    border: 1px solid #aaa;
}
.search-bar button {
    padding: 10px 15px;
    background: #800000;
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
}

/* Book Cards */
.book-container {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 15px;
    padding: 20px;
}
.card {
    background: #fff;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
    text-align: center;
    padding: 10px;
    transition: 0.3s;
}
.card:hover {
    transform: translateY(-5px);
}
.card img {
    width: 100%;
    height: 200px;
    border-radius: 10px;
}

/* Aside Banner */
.aside-banner {
    background: #ffe6cc;
    margin: 30px;
    padding: 20px;
    border-left: 6px solid #800000;
    text-align: center;
    border-radius: 10px;
}
.aside-banner button {
    background: #800000;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    margin-top: 10px;
}

/* Register Form */
.register-form {
    text-align: center;
    background: #f9f9f9;
    padding: 30px;
}
.hidden {
    display: none;
}
.register-form form input {
    display: block;
    margin: 10px auto;
    padding: 10px;
    width: 250px;
    border-radius: 8px;
    border: 1px solid #ccc;
}
.register-form form button {
    background: #800000;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
}

/* Footer */
footer {
    background: #800000;
    color: white;
    text-align: center;
    padding: 15px;
}

/* Responsive */
@media (max-width: 1024px) {
    .book-container {
        grid-template-columns: repeat(2, 1fr);
    }
}
@media (max-width: 600px) {
    .book-container {
        grid-template-columns: 1fr;
    }
}