/* 基础重置和字体 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: #e0e0e0;
  color: #333;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* 容器撑满 */
main {
  flex: 1;
  padding: 2em;
  max-width: 900px;
  margin: 0 auto;
  background: #e0e0e0;
  box-shadow: 10px 10px 30px #bebebe,
              -10px -10px 30px #ffffff;
  border-radius: 20px;
}

/* 头部 */
header {
  background: #e0e0e0;
  padding: 1em 2em;
  box-shadow: inset 6px 6px 12px #bebebe,
              inset -6px -6px 12px #ffffff;
  border-radius: 20px;
  margin: 1em auto;
  max-width: 900px;
  text-align: center;
}

header h1 {
  font-weight: 700;
  font-size: 2em;
  margin-bottom: 0.5em;
}

/* 导航 */
nav a {
  display: inline-block;
  margin: 0 1em;
  padding: 0.5em 1.2em;
  color: #444;
  text-decoration: none;
  border-radius: 12px;
  background: #e0e0e0;
  box-shadow: 6px 6px 12px #bebebe,
              -6px -6px 12px #ffffff;
  transition: box-shadow 0.3s ease, color 0.3s ease;
  font-weight: 600;
}

nav a:hover {
  box-shadow: inset 4px 4px 8px #bebebe,
              inset -4px -4px 8px #ffffff;
  color: #222;
}

/* 文章标题 */
section h2 {
  font-weight: 700;
  font-size: 1.8em;
  margin-bottom: 0.5em;
}

/* 段落 */
section p {
  line-height: 1.6;
  margin-bottom: 1em;
}

/* 页脚 */
footer {
  background: #e0e0e0;
  padding: 1em 2em;
  box-shadow: inset 6px 6px 12px #bebebe,
              inset -6px -6px 12px #ffffff;
  border-radius: 20px;
  text-align: center;
  max-width: 900px;
  margin: 1em auto;
  font-size: 0.9em;
  color: #666;
}

footer a {
  color: #444;
  text-decoration: none;
  font-weight: 600;
}

footer a:hover {
  text-decoration: underline;
}