/* 全局样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Microsoft YaHei", sans-serif;
}

/* 容器 */
.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
}

/* 导航栏 */
.navbar {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
}

.nav-links {
    display: flex;
    list-style: none;
}

.nav-links li {
    margin-left: 2rem;
}

.nav-links a {
    color: white;
    text-decoration: none;
    font-size: 1rem;
}

.nav-links a.active {
    color: #3498db;
    font-weight: bold;
}

/* 首页英雄区 */
.hero {
    background-color: #f5f7fa;
    padding: 4rem 0;
    text-align: center;
}

.hero h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: #2c3e50;
}

.hero p {
    font-size: 1.1rem;
    color: #666;
    max-width: 800px;
    margin: 0 auto;
}

/* 学习笔记板块 */
.notes {
    padding: 4rem 0;
}

.notes h3 {
    font-size: 1.8rem;
    text-align: center;
    margin-bottom: 2rem;
    color: #2c3e50;
}

.note-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.note-item {
    background-color: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.note-item h4 {
    font-size: 1.2rem;
    margin-bottom: 0.8rem;
    color: #3498db;
}

.note-item p {
    color: #666;
    line-height: 1.6;
}

/* 关于我板块 */
.about {
    padding: 4rem 0;
    background-color: #f5f7fa;
}

.about h3 {
    font-size: 1.8rem;
    text-align: center;
    margin-bottom: 2rem;
    color: #2c3e50;
}

.about p {
    font-size: 1.1rem;
    color: #666;
    max-width: 800px;
    margin: 0 auto;
    line-height: 1.8;
    text-align: center;
}

/* 底部 */
.footer {
    background-color: #2c3e50;
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer p {
    font-size: 0.9rem;
}

/* 回到顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: #3498db;
    color: white;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    display: none;
}

/* 移动端适配 */
@media (max-width: 768px) {
    .navbar .container {
        flex-direction: column;
    }

    .nav-links {
        margin-top: 1rem;
    }

    .nav-links li {
        margin-left: 1rem;
        margin-right: 1rem;
    }

    .hero h2 {
        font-size: 1.8rem;
    }

    .notes h3, .about h3 {
        font-size: 1.6rem;
    }
}