/* Modern Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: #fafafa;
}

/* Typography */
h1, h2, h3 {
    color: #2c3e50;
    margin-bottom: 15px;
    font-weight: 600;
}

p {
    margin-bottom: 15px;
    color: #555;
}

/* Layout Container */
.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header & Navigation */
header {
    background-color: #fff;
    padding: 40px 0 20px;
    border-bottom: 1px solid #eaeaea;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    margin-bottom: 5px;
}
/* 基础重置 */
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: Arial, Helvetica, sans-serif;
    color: #555;
    line-height: 1.6;
    background-color: #ffffff;
}
.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 天蓝色渐变背景头部 */
.sky-header {
    background: linear-gradient(to bottom, #aedbf0 0%, #ffffff 100%);
    padding: 40px 0 20px 0;
    margin-bottom: 40px;
    border-bottom: 1px solid #e0e0e0;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    flex-wrap: wrap;
    gap: 20px;
}

.title-area h1 {
    color: #2c6c94;
    font-size: 2.2rem;
    margin-bottom: 5px;
}
.motto {
    color: #5da3c7;
    font-weight: bold;
    font-size: 0.95rem;
}

/* 胶囊导航按钮 (致敬旧版的橘色与绿色块) */
.pill-nav {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.nav-btn {
    display: inline-block;
    padding: 12px 24px;
    background-color: #7CB342; /* 经典绿 */
    color: white;
    text-decoration: none;
    font-weight: bold;
    border-radius: 25px; /* 变圆润 */
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: all 0.2s ease;
}

.nav-btn:hover {
    background-color: #689f38;
    transform: translateY(-2px);
}

.nav-btn.active {
    background-color: #FF8A65; /* 经典橘色 */
}

.nav-btn.active:hover {
    background-color: #e67552;
}

/* 主体内容排版 */
.content-block {
    margin-bottom: 50px;
}
.section-title {
    color: #FF6820; /* 沿用您旧版的橙色标题 */
    font-size: 1.4rem;
    margin-bottom: 20px;
    border-bottom: 2px solid #f0f0f0;
    padding-bottom: 5px;
}
p { margin-bottom: 15px; }

/* 突出显示框 (用于书籍) */
.highlight-box {
    background-color: #f9fbfd;
    border-left: 4px solid #7CB342;
    padding: 20px;
    border-radius: 4px;
}
.highlight-box h3 { margin-bottom: 5px; color: #333; }
.clean-list {
    list-style: none;
    margin: 15px 0;
}
.clean-list li { margin-bottom: 5px; }

.text-link {
    color: #2c6c94;
    text-decoration: none;
    font-weight: bold;
}
.text-link:hover { text-decoration: underline; }

/* 页脚 */
footer {
    text-align: center;
    padding: 30px;
    margin-top: 40px;
    color: #aaa;
    font-size: 0.9rem;
}


/* --- 新增：左右分栏布局 --- */
.layout-wrapper {
    display: flex;
    gap: 40px; /* 图片和文字之间的间距 */
    align-items: flex-start;
}

.sidebar {
    flex: 0 0 300px;
    position: sticky;
    top: 40px; /* 这是滚动时图片距离浏览器顶部的吸附距离，保持不变 */
    align-self: flex-start;
    
    /* --- 新增下面这行来微调初始位置 --- */
    margin-top: 20px; /* 往下推 25 像素。您可以根据浏览器的实际显示效果，把这个数值在 15px 到 30px 之间微调，直到严丝合缝对齐为止 */
}

.sidebar-img {
    width: 100%;
    height: auto;
    border-radius: 8px; /* 给图片加一点点圆角，显得更现代 */
    box-shadow: 0 4px 12px rgba(0,0,0,0.05); /* 加一点淡淡的阴影 */
}

.main-content {
    flex: 1; /* 右侧文字自动填满剩余空间 */
}

.paper-list li {
    margin-bottom: 12px;
    padding-left: 15px;
    border-left: 3px solid #7CB342; /* 给论文列表加一个绿色的引导线，呼应导航栏 */
}

/* 手机端响应式适配：屏幕变窄时，图片自动跑到文字上方 */
@media (max-width: 768px) {
    .layout-wrapper {
        flex-direction: column;
    }
    .sidebar {
        flex: auto;
        width: 100%;
        max-width: 400px;
        margin: 0 auto 30px auto;
    }
}