/* 定义CSS变量，方便统一管理颜色 */
:root {
  /* 主色调 - 象征科技与信任的蓝色系 */
  --primary-dark-blue: #1A237E;
  --primary-light-blue: #29B6F6;
  /* 辅助色 - 中性色 */
  --neutral-grey: #EEEEEE;
  /* 点缀色 - 橙色 */
  --accent-orange: #FFC107;
  /* 背景渐变色 */
  --background-gradient: linear-gradient(135deg, #42A5F5, #7E57C2);
}

/* 全局样式 */
body {
  margin: 0;
  padding: 0;
  font-family: 'Helvetica Neue', Arial, sans-serif;
  background: var(--background-gradient);
  color: var(--neutral-grey);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

/* 固定顶部导航栏 */
.header {
  background-color: var(--primary-dark-blue);
  color: #fff;
  padding: 20px 0;
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 15px;
}

.logo {
  font-size: 1.5em;
  font-weight: bold;
}

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

.nav-item {
  margin: 0 10px;
  color: #fff;
  text-decoration: none;
  position: relative;
  transition: color 0.3s;
}

.nav-item:hover {
  color: var(--accent-orange);
}

.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #fff;
  min-width: 160px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.2);
  top: 100%;
  left: 0;
  z-index: 1001;
}

.dropdown-content a {
  color: #333;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  transition: background-color 0.3s;
}

.dropdown-content a:hover {
  background-color: #f1f1f1;
}

.dropdown:hover .dropdown-content {
  display: block;
}

/* 主内容区 */
.main-content {
  flex: 1;
  padding: 100px 15px 40px; /* 考虑导航栏高度 */
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

/* 文章提示 */
.reference-note {
  background-color: rgba(255, 193, 7, 0.1);
  border-left: 4px solid var(--accent-orange);
  padding: 15px;
  margin-bottom: 20px;
  font-size: 1.2em;
  color: #fff;
}

/* 文章样式 */
article {
  background-color: rgba(33, 33, 33, 0.8);
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
  color: #fff;
}

/* 文章标题 */
article h2, article h3 {
  color: var(--accent-orange);
}

/* 文章段落 */
article p {
  line-height: 1.6;
  margin-bottom: 15px;
}

/* 代码块样式 */
article pre {
  background-color: #2E2E2E;
  padding: 15px;
  border-radius: 5px;
  overflow-x: auto;
  margin-bottom: 20px;
}

article code {
  color: #FFC107;
  font-family: 'Courier New', Courier, monospace;
}

/* 图片样式 */
.article-image {
  max-width: 650px;
  width: 100%;
  border-radius: 10px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
  transition: transform 0.3s, box-shadow 0.3s;
  margin: 20px 0;
}

.article-image:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 16px rgba(0,0,0,0.3);
}

/* 卡片样式 */
.card {
  background-color: #FFFFFF;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  margin: 20px 0;
  padding: 20px;
  transition: transform 0.3s;
  background-color: rgba(255, 255, 255, 0.1);
}

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

/* 响应式布局 */
@media (min-width: 576px) {
  .main-content {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 992px) {
  .main-content {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* 按钮样式 */
.button {
  background-color: var(--accent-orange);
  border: none;
  border-radius: 4px;
  color: #fff;
  cursor: pointer;
  padding: 10px 20px;
  transition: background-color 0.3s, transform 0.3s;
  font-size: 1em;
}

.button:hover {
  background-color: #FFA000;
  transform: scale(1.05);
}

/* 渐变动画 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeInUp 1s ease-out forwards;
}

/* 加载动画 */
.loader {
  border: 8px solid #f3f3f3;
  border-top: 8px solid var(--primary-light-blue);
  border-radius: 50%;
  width: 60px;
  height: 60px;
  animation: spin 1.5s linear infinite;
  margin: 100px auto;
}

@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

/* 表格样式 */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
  background-color: rgba(255, 255, 255, 0.1);
}

thead {
  background-color: var(--primary-dark-blue);
  color: #fff;
}

th, td {
  padding: 12px 15px;
  border: 1px solid #ddd;
  text-align: left;
}

tbody tr:nth-child(even) {
  background-color: rgba(255, 255, 255, 0.05);
}

tbody tr:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

/* 页脚样式 */
.footer {
  background-color: var(--primary-dark-blue);
  color: #fff;
  text-align: center;
  padding: 20px 0;
}

/* 隐藏导航栏中的“联系我们”文本 */
.nav-item.contact {
  display: none;
}

/* 高级CSS效果 */
.card {
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(10px);
}

.modal {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(26, 35, 126, 0.9);
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.3);
  display: none;
  z-index: 1002;
}

.modal.active {
  display: block;
}

.modal-close {
  position: absolute;
  top: 15px;
  right: 20px;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5em;
  cursor: pointer;
}

@media (max-width: 500px) {
  article {
    padding: 15px;
  }
}