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

body {
    background-color: #f4f4f9;
    color: #333;
    min-height: 100vh;
}

/* --- Header Styling --- */
header {
    background-color: #4a4e69;
    color: white;
    padding: 20px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

header h1 {
    font-size: 1.8rem;
}

#new-book-btn {
    background-color: #88d498;
    color: #333;
    border: none;
    padding: 10px 15px;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
    transition: background-color 0.2s;
}

#new-book-btn:hover {
    background-color: #61c28b;
}

main {
    padding: 20px 30px;
}

/* --- Book Display Grid --- */
#book-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    padding-top: 20px;
}

.book-card {
    background-color: white;
    border: 1px solid #ddd;
    border-radius: 8px;
    padding: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.book-card h3 {
    margin-bottom: 10px;
    color: #222;
    font-size: 1.5rem;
}

.read-status {
    padding: 5px 10px;
    border-radius: 4px;
    text-align: center;
    font-weight: bold;
    margin: 10px 0;
}

.read-true {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.read-false {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.card-actions {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 15px;
}

.card-actions button {
    padding: 8px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.2s;
}

.toggle-read-btn {
    background-color: #90b8f8;
    color: white;
}

.toggle-read-btn:hover {
    background-color: #6c9af0;
}

.remove-btn {
    background-color: #f94144;
    color: white;
}

.remove-btn:hover {
    background-color: #d82b2e;
}

/* --- Sidebar Styling --- */
.sidebar {
    height: 100%;
    width: 0; /* Initially hidden */
    position: fixed;
    z-index: 10;
    top: 0;
    right: 0;
    background-color: #fff;
    overflow-x: hidden;
    transition: width 0.5s;
    box-shadow: -4px 0 8px rgba(0, 0, 0, 0.1);
}

.sidebar.open {
    width: 350px;
}

.sidebar-content {
    padding: 20px;
}

.close-btn {
    position: absolute;
    top: 10px;
    right: 25px;
    font-size: 30px;
    border: none;
    background: none;
    cursor: pointer;
}

#new-book-form label {
    display: block;
    margin-top: 15px;
    margin-bottom: 5px;
    font-weight: bold;
}

#new-book-form input[type="text"],
#new-book-form input[type="number"] {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
}

.read-checkbox-group {
    display: flex;
    align-items: center;
    margin: 20px 0;
}

.read-checkbox-group input[type="checkbox"] {
    margin-right: 10px;
    width: 20px;
    height: 20px;
}

#new-book-form button[type="submit"] {
    background-color: #4a4e69;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    width: 100%;
    margin-top: 10px;
}

@media screen and (max-width: 600px) {
    header {
        padding: 15px 20px;
        flex-direction: column;
        gap: 10px;
    }

    #new-book-btn {
        width: 100%;
    }
    main {
        padding: 15px;
    }

    .sidebar.open {
        width: 100%;
    } 
}