/* ========================================
   CSS 变量定义
   ======================================== */
:root {
  /* 颜色 */
  --bg: #FFFFFF;
  --bg-alt: #F8F9FA;
  --text: #333333;
  --text-muted: #6C757D;
  --black: #000000;
  --border: #E0E0E0;
  --white: #FFFFFF;

  /* 间距 */
  --spacing-xs: 24px;
  --spacing-md: 48px;
  --spacing-lg: 96px;

  /* 字体 */
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
}

/* ========================================
   全局重置
   ======================================== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  color: var(--text);
  background-color: var(--bg);
  line-height: 1.6;
}

/* ========================================
   容器
   ======================================== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-xs);
}

/* ========================================
   粘性导航栏
   ======================================== */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.nav__logo {
  font-size: 18px;
  font-weight: 700;
  color: var(--black);
  letter-spacing: 2px;
}

.nav__links {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 32px;
}

.nav__links a {
  text-decoration: none;
  color: var(--text);
  font-size: 14px;
  transition: color 0.2s;
}

.nav__links a:hover {
  color: var(--black);
}

/* ========================================
   英雄区块
   ======================================== */
.hero {
  padding: var(--spacing-lg) 0 var(--spacing-md);
  border-bottom: 1px solid var(--border);
}

.hero__title {
  font-size: clamp(32px, 6vw, 56px);
  font-weight: 300;
  color: var(--text);
  margin: 0 0 16px;
  line-height: 1.2;
}

.hero__subtitle {
  max-width: 600px;
  color: var(--text-muted);
  font-size: 18px;
  margin: 0;
  line-height: 1.6;
}

/* ========================================
   区块标题
   ======================================== */
.section-title {
  font-size: 24px;
  font-weight: 300;
  color: var(--text);
  margin: 0 0 var(--spacing-md);
  letter-spacing: 1px;
}

/* ========================================
   服务网格
   ======================================== */
.services {
  padding: var(--spacing-lg) 0;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-xs);
}

/* ========================================
   服务卡片
   ======================================== */
.card {
  background-color: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: var(--spacing-xs);
  display: flex;
  flex-direction: column;
}

.card h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
}

.card p {
  color: var(--text-muted);
  font-size: 14px;
  margin: 0 0 16px;
  flex-grow: 1;
}

/* 可访问服务卡片 */
.card--accessible {
  text-decoration: none;
  color: inherit;
  transition: border-color 0.2s;
}

.card--accessible:hover {
  border-color: var(--black);
  cursor: pointer;
}

/* 后端服务卡片 */
.card--backend {
  cursor: default;
}

/* ========================================
   分类标签
   ======================================== */
.tag {
  display: inline-block;
  font-size: 11px;
  padding: 4px 16px;
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text-muted);
  align-self: flex-start;
  width: fit-content;
}

.tag--backend {
  border-color: var(--border);
  color: var(--text-muted);
}

.tag--ready {
  border-color: #8bb89a;
  color: #6a9b7a;
}

.tag--byk {
  border-color: #bfa882;
  color: #9c8764;
  cursor: help;
}

.card__tags {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: auto;
}

/* ========================================
   图标
   ======================================== */
.icon {
  width: 16px;
  height: 16px;
  vertical-align: -2px;
  margin-right: 4px;
}

/* ========================================
   状态指示灯
   ======================================== */
.card {
  position: relative;
}

.status-dot {
  position: absolute;
  right: 16px;
  bottom: 16px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--border);
}

.status-dot--up {
  background-color: #4caf50;
  animation: breathe-up 3s ease-in-out infinite;
}

.status-dot--down {
  background-color: #e57373;
  animation: breathe-down 3s ease-in-out infinite;
}

@keyframes breathe-up {
  0%, 100% { opacity: 0.7; box-shadow: 0 0 0 0 rgba(76, 175, 80, 0); }
  50% { opacity: 1; box-shadow: 0 0 8px 3px rgba(76, 175, 80, 0.3); }
}

@keyframes breathe-down {
  0%, 100% { opacity: 0.7; box-shadow: 0 0 0 0 rgba(229, 115, 115, 0); }
  50% { opacity: 1; box-shadow: 0 0 8px 3px rgba(229, 115, 115, 0.3); }
}

/* ========================================
   关于区块
   ======================================== */
.about {
  padding: var(--spacing-lg) 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.about__grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: var(--spacing-md);
  align-items: start;
}

.about__intro p {
  color: var(--text-muted);
  font-size: 16px;
  margin: 0 0 16px;
  line-height: 1.8;
}

.about__info h3 {
  font-size: 24px;
  font-weight: 300;
  color: var(--text);
  margin: 0 0 var(--spacing-md);
  letter-spacing: 1px;
}

.about__info ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.about__info li {
  margin-bottom: 12px;
}

.about__info a {
  color: var(--text);
  text-decoration: none;
  font-size: 14px;
  transition: color 0.2s;
}

.about__info a:hover {
  color: var(--black);
}

/* ========================================
   页脚
   ======================================== */
.footer {
  padding: var(--spacing-md) 0;
}

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

.footer__copyright {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0;
}

.footer__social {
  display: flex;
  gap: 16px;
}

.footer__social a {
  font-size: 14px;
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.2s;
}

.footer__social a:hover {
  color: var(--black);
}

/* ========================================
   响应式媒体查询
   ======================================== */

/* 平板断点：<= 1024px */
@media (max-width: 1024px) {
  .grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .about__grid {
    grid-template-columns: 1fr;
  }

  .hero {
    padding: var(--spacing-md) 0 var(--spacing-xs);
  }

  .services {
    padding: var(--spacing-md) 0;
  }

  .about {
    padding: var(--spacing-md) 0;
  }

  .section-title {
    margin-bottom: var(--spacing-xs);
  }
}

/* 移动端断点：<= 768px */
@media (max-width: 768px) {
  .grid {
    grid-template-columns: 1fr;
  }

  .nav__links {
    display: none;
  }

  .footer__inner {
    flex-direction: column;
    text-align: center;
    gap: 16px;
  }

  .hero {
    padding: var(--spacing-xs) 0;
  }

  .services {
    padding: var(--spacing-xs) 0;
  }

  .about {
    padding: var(--spacing-xs) 0;
  }

  .container {
    padding: 0 16px;
  }

  .footer {
    padding: var(--spacing-xs) 0;
  }

  .section-title {
    margin-bottom: 16px;
  }
}