/* ======================
   全局重置与基础样式
   ====================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Source Han Serif CN', 'SimSun', serif;
    font-weight: 400;
    line-height: 1.8;
    color: #1a1a1a;
    background-color: #fdf6e3;
    padding: 0;
    margin: 0;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ======================
   顶部导航栏
   ====================== */
header {
    background-color: #ffffff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid #eee;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    font-size: 1.8em;
    font-weight: bold;
    color: #c00;
    text-decoration: none;
    font-family: 'Source Han Serif CN', 'SimSun', serif;
}

nav ul {
    display: flex;
    list-style: none;
}

nav ul li {
    margin-left: 30px;
}

nav ul li a {
    text-decoration: none;
    color: #1a1a1a;
    font-weight: 500;
    transition: color 0.3s;
    font-size: 1.1em;
}

nav ul li a:hover {
    color: #c00;
}

.user-nav {
    display: flex;
    align-items: center;
}

.user-nav a {
    color: #1a1a1a;
    text-decoration: none;
    margin-left: 20px;
    font-weight: 500;
    transition: color 0.3s;
    font-size: 1.1em;
}

.user-nav a:hover {
    color: #c00;
}

/* ======================
   英雄区域 (Hero Section)
   ====================== */
.hero {
    background: linear-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.5)), url('https://images.unsplash.com/photo-1507842217343-583bb7270b66?ixlib=rb-1.2.1&auto=format&fit=crop&w=1950&q=80') center/cover no-repeat;
    height: 80vh;
    display: flex;
    align-items: center;
    text-align: center;
    color: white;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 20px;
}

.hero-content h1 {
    font-size: 3.5em;
    margin-bottom: 20px;
    font-weight: bold;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

.hero-content p {
    font-size: 1.5em;
    margin-bottom: 30px;
    text-shadow: 0 1px 2px rgba(0,0,0,0.3);
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 30px;
}

/* ======================
   特色区域 (Features Section)
   ====================== */
.features {
    padding: 80px 0;
    background-color: #fff;
}

.features h2 {
    text-align: center;
    font-size: 2.5em;
    margin-bottom: 50px;
    color: #c00;
    font-weight: bold;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.feature-card {
    background-color: #fdf6e3;
    border-radius: 8px;
    padding: 30px;
    text-align: center;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-10px);
}

.feature-card h3 {
    font-size: 1.8em;
    margin: 20px 0;
    color: #1a1a1a;
    font-weight: bold;
}

.feature-card p {
    color: #333;
    margin-bottom: 20px;
    font-size: 1.1em;
    line-height: 1.7;
}

/* ======================
   页脚 (Footer)
   ====================== */
footer {
    background-color: #1a1a1a;
    color: #fff;
    padding: 40px 0;
    margin-top: 80px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
}

.footer-column {
    flex: 1;
    min-width: 200px;
    margin-bottom: 20px;
}

.footer-column h3 {
    font-size: 1.5em;
    margin-bottom: 20px;
    color: #c00;
}

.footer-column p, .footer-column a {
    color: #ccc;
    line-height: 1.6;
    text-decoration: none;
    display: block;
    margin-bottom: 10px;
    transition: color 0.3s;
}

.footer-column a:hover {
    color: #fff;
}

/* ======================
   通用按钮样式
   ====================== */
.btn {
    display: inline-block;
    padding: 12px 30px;
    background-color: #c00;
    color: white;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    transition: background-color 0.3s;
    font-size: 1.1em;
    border: 2px solid #c00;
}

.btn:hover {
    background-color: transparent;
    color: #c00;
}

/* ======================
   表单通用样式
   ====================== */
form {
    max-width: 500px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 25px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: bold;
    color: #1a1a1a;
}

.form-group input[type="text"],
.form-group input[type="email"],
.form-group input[type="password"],
.form-group textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-family: 'Source Han Serif CN', 'SimSun', serif;
    font-size: 1.1em;
    line-height: 1.5;
}

.form-group input[type="submit"] {
    background-color: #c00;
    color: white;
    border: none;
    cursor: pointer;
    font-weight: bold;
    font-size: 1.1em;
    padding: 12px 20px;
    transition: background-color 0.3s;
}

.form-group input[type="submit"]:hover {
    background-color: #a00;
}

/* ======================
   登录/注册容器
   ====================== */
.auth-container {
    max-width: 500px;
    margin: 40px auto;
    padding: 30px;
    background-color: #fff;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

.auth-container h2 {
    text-align: center;
    margin-bottom: 30px;
    color: #c00;
    font-size: 2.2em;
    font-weight: bold;
}

/* ======================
   书籍列表卡片
   ====================== */
.book-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 20px;
}

.book-card {
    background-color: #fff;
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: transform 0.3s;
}

.book-card:hover {
    transform: translateY(-5px);
}

.book-cover {
    width: 100%;
    height: 300px;
    background-color: #f0f0f0;
    display: flex;
    justify-content: center;
    align-items: center;
    color: #ccc;
    font-size: 1.2em;
    font-weight: bold;
}

.book-info {
    padding: 20px;
}

.book-title {
    font-size: 1.4em;
    margin-bottom: 10px;
    color: #1a1a1a;
    font-weight: bold;
    text-align: center;
}

.book-author {
    text-align: center;
    color: #c00;
    font-weight: bold;
}