/* 主内容区域 */
.main-content {
    margin-left: 0;
    padding: 2rem;
}

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

.welcome-text {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.date-text {
    color: var(--text-secondary);
}

/* 搜索区域 */
.search-section {
    background: white;
    border-radius: 12px;
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.search-box {
    display: flex;
    margin-bottom: 1.5rem;
}

.search-input {
    flex: 1;
    padding: 1rem 1.5rem;
    border: 2px solid var(--light-gray);
    border-radius: 8px 0 0 8px;
    font-size: 1rem;
    outline: none;
    transition: var(--transition);
}

.search-input:focus {
    border-color: var(--accent-blue);
}

.search-btn {
    background: var(--accent-blue);
    color: white;
    border: none;
    padding: 0 1.5rem;
    border-radius: 0 8px 8px 0;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
}

.search-btn:hover {
    background: var(--secondary-blue);
}

.filter-row {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.filter-group {
    flex: 1;
    min-width: 180px;
}

.filter-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.filter-select {
    width: 100%;
    padding: 0.8rem;
    border: 2px solid var(--light-gray);
    border-radius: 8px;
    background: white;
    cursor: pointer;
}

/* 书籍列表 */
.books-section {
    margin-bottom: 2rem;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.section-title {
    font-size: 1.3rem;
    font-weight: 600;
}

.view-all {
    color: var(--accent-blue);
    text-decoration: none;
    font-weight: 500;
}

.books-grid {
    display: grid;
    /* 强制一行 4 列，1fr 表示平均分配剩余空间 */
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    /* 卡片间距 */
    width: 100%;
}

.book-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
}

.book-cover {
    height: 200px;
    /* 固定高度 */
    width: 100%;
    overflow: hidden;
}

.book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    /* 确保图片填满且不变形 */
    transition: transform 0.3s ease;
}

.book-card:hover .book-cover img {
    transform: scale(1.05);
}

.book-details {
    padding: 1.5rem;
}

.book-title {
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--primary-blue);
}

.book-meta {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.book-description {
    margin-bottom: 1.5rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-actions {
    display: flex;
    justify-content: space-between;
}

.book-status {
    display: inline-flex;
    align-items: center;
    padding: 0.4rem 0.8rem;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

.status-available {
    background: rgba(56, 161, 105, 0.15);
    color: var(--success-green);
}

.status-borrowed {
    background: rgba(229, 62, 62, 0.15);
    color: var(--error-red);
}

.action-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.btn-borrow {
    background: var(--accent-blue);
    color: white;
    border: none;
}

.btn-borrow:hover {
    background: var(--secondary-blue);
}

/*  未收藏状态（默认）：蓝底白字 */
.btn-favorite {
    background: var(--accent-blue);
    color: white;
    border: 1px solid var(--accent-blue);
    transition: all 0.3s ease;
}

.btn-favorite:hover {
    background: var(--secondary-blue);
    border-color: var(--secondary-blue);
}
.btn-favorite i {
    color: white;
    /* 确保图标也是白色 */
}

/*已收藏状态：白底黑字，禁止点击 */
.btn-favorite.is-favorited {
    background: white;
    color: var(--text-primary); /* 黑灰色 */
    border: 1px solid var(--light-gray);
    cursor: default; /* 鼠标样式变为默认，暗示不可点 */
    opacity: 0.8;
}

.btn-favorite.is-favorited:hover {
    background: white; /* 悬停不改变背景 */
    color: var(--text-primary);
}

.btn-favorite.is-favorited i {
    color: var(--accent-blue); /* 已收藏的爱心图标可以是蓝色或红色，这里设为蓝色呼应 */
}

/* 响应式保护：虽然要求一行4个，但在极小屏幕（如手机）强制4个会没法看
   建议在平板尺寸以下（<1024px）才切换为少于4列，保证桌面端体验符合要求 */
@media (max-width: 1024px) {
    .books-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    .books-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 480px) {
    .books-grid {
        grid-template-columns: 1fr;
    }
}