/* 颜色变量定义 */
:root {
  --主色-科技蓝: #1E90FF;
  --辅色-稳重灰: #2F4F4F;
  --点缀色-活力橙: #FFA500;
  --点缀色-鲜绿: #32CD32;
  --背景-渐变: linear-gradient(135deg, #1E90FF, #2F4F4F);
  --文字主色: #FFFFFF;
  --文字副色: #F0F0F0;
  --阴影色: rgba(0, 0, 0, 0.2);
}

/* 全局样式 */
body {
  margin: 0;
  padding: 0;
  font-family: 'Open Sans', sans-serif;
  background: var(--背景-渐变);
  color: var(--文字主色);
  line-height: 1.6;
  overflow-x: hidden;
}

/* 导航栏样式 */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: var(--辅色-稳重灰);
  display: flex;
  justify-content: space-around;
  align-items: center;
  padding: 15px 0;
  box-shadow: 0 2px 4px var(--阴影色);
  z-index: 1000;
}

.navbar ul {
  list-style: none;
  display: flex;
  gap: 30px;
  margin: 0;
  padding: 0;
}

.navbar li {
  position: relative;
}

.navbar a {
  color: var(--文字主色);
  text-decoration: none;
  font-size: 18px;
  transition: color 0.3s;
}

.navbar a:hover {
  color: var(--点缀色-活力橙);
}

.dropdown {
  display: none;
  position: absolute;
  top: 50px;
  left: 0;
  background-color: var(--辅色-稳重灰);
  padding: 10px 0;
  border-radius: 5px;
  box-shadow: 0 2px 8px var(--阴影色);
}

.navbar li:hover .dropdown {
  display: block;
}

.dropdown a {
  display: block;
  padding: 10px 20px;
  font-size: 16px;
}

.dropdown a:hover {
  background-color: var(--辅色-稳重灰);
  color: var(--点缀色-鲜绿);
}

/* 主内容区样式 */
.container {
  max-width: 1200px;
  margin: 100px auto 50px;
  padding: 20px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
  gap: 40px;
}

.section {
  background-color: rgba(47, 79, 79, 0.8);
  padding: 30px;
  border-radius: 10px;
  box-shadow: 0 4px 12px var(--阴影色);
  position: relative;
}

.section h2, .section h3, .section h4 {
  color: var(--点缀色-活力橙);
}

.section p {
  font-size: 16px;
  color: var(--文字副色);
  margin-bottom: 20px;
}

.code-block {
  background-color: #333;
  padding: 20px;
  border-radius: 5px;
  overflow-x: auto;
  box-shadow: 0 2px 6px var(--阴影色);
}

.code-block code {
  color: #f8f8f2;
  font-family: 'Courier New', Courier, monospace;
  display: block;
  white-space: pre-wrap;
}

.code-block::before {
  content: 'CSS3 示例代码';
  display: block;
  background-color: var(--点缀色-鲜绿);
  color: #fff;
  padding: 5px 10px;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
  font-size: 14px;
}

/* 图片样式 */
.image-container {
  position: relative;
  overflow: hidden;
  border-radius: 10px;
  box-shadow: 0 4px 8px var(--阴影色);
}

.image-container img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform 0.3s, filter 0.3s;
}

.image-container img:hover {
  transform: scale(1.05);
  filter: brightness(1.1);
}

/* 按钮样式 */
.button {
  background: linear-gradient(45deg, var(--主色-科技蓝), var(--点缀色-活力橙));
  color: var(--文字主色);
  padding: 12px 24px;
  border: none;
  border-radius: 5px;
  font-size: 16px;
  cursor: pointer;
  transition: transform 0.3s, background 0.3s;
}

.button:hover {
  transform: scale(1.05);
  background: linear-gradient(45deg, var(--点缀色-活力橙), var(--点缀色-鲜绿));
}

/* 卡片布局样式 */
.card-container {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.card {
  perspective: 1000px;
}

.card-inner {
  position: relative;
  width: 100%;
  height: 300px;
  text-align: center;
  transition: transform 0.8s;
  transform-style: preserve-3d;
}

.card:hover .card-inner {
  transform: rotateY(180deg);
}

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: 10px;
  box-shadow: 0 4px 8px var(--阴影色);
}

.card-front {
  background-color: var(--主色-科技蓝);
  color: var(--文字主色);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.card-back {
  background-color: var(--辅色-稳重灰);
  color: var(--文字主色);
  transform: rotateY(180deg);
  padding: 20px;
}

/* 加载动画样式 */
.loader {
  border: 8px solid var(--辅色-稳重灰);
  border-top: 8px solid var(--主色-科技蓝);
  border-radius: 50%;
  width: 60px;
  height: 60px;
  animation: spin 1s linear infinite;
  margin: 50px auto;
}

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

/* 滤镜效果 */
.illustration {
  width: 100%;
  height: auto;
  filter: grayscale(50%) contrast(1.2);
  transition: filter 0.3s;
}

.illustration:hover {
  filter: grayscale(0%) contrast(1);
}

/* 响应式设计 */
@media (max-width: 768px) {
  .navbar ul {
    flex-direction: column;
    gap: 15px;
    background-color: var(--辅色-稳重灰);
    position: absolute;
    top: 60px;
    left: 0;
    width: 100%;
    display: none;
  }
  
  .navbar.active ul {
    display: flex;
  }
  
  .container {
    grid-template-columns: 1fr;
  }
}

/* 提示文字样式 */
.reference-note {
  text-align: center;
  font-size: 18px;
  color: var(--点缀色-鲜绿);
  margin: 20px 0;
}

/* 折叠区域样式 */
.collapsible {
  background-color: var(--辅色-稳重灰);
  color: var(--文字主色);
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 18px;
  transition: background 0.3s;
  border-radius: 5px;
}

.active, .collapsible:hover {
  background-color: var(--主色-科技蓝);
}

.content {
  padding: 0 18px;
  display: none;
  overflow: hidden;
  background-color: var(--辅色-稳重灰);
  border-radius: 5px;
}

.content p {
  margin: 15px 0;
}

/* 代码块样式 */
pre code {
  background-color: #2d2d2d;
  color: #ccc;
  padding: 15px;
  border-radius: 5px;
  display: block;
  overflow-x: auto;
}

pre code::before {
  content: 'CSS3 示例代码';
  display: block;
  background-color: var(--点缀色-鲜绿);
  color: white;
  padding: 5px 10px;
  border-top-left-radius: 5px;
  border-top-right-radius: 5px;
  font-size: 14px;
}

/* 视觉过渡引导区样式 */
.hero {
  height: 500px;
  background: url('https://images.gptkong.com/demo/sample1.png') no-repeat center center/cover;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
}

.hero::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(30, 144, 255, 0.5);
}

.hero-content {
  position: relative;
  color: var(--文字主色);
  font-size: 3rem;
  text-align: center;
  z-index: 1;
  animation: fadeIn 2s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* 按钮悬停效果 */
.link {
  color: var(--主色-科技蓝);
  text-decoration: none;
  position: relative;
  transition: color 0.3s, transform 0.3s;
}

.link::after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  background: var(--点缀色-活力橙);
  left: 50%;
  bottom: -5px;
  transition: width 0.3s, left 0.3s;
}

.link:hover {
  color: var(--点缀色-活力橙);
  transform: scale(1.05);
}

.link:hover::after {
  width: 100%;
  left: 0;
}