/* ============================================
   深圳书谷投资有限公司 - 主域名企业官网
   简约商务蓝灰风格（独立部署于 shugutouzi.com）
   ============================================ */

:root {
  --primary: #1f4e79;        /* 主蓝 */
  --primary-dark: #163a5c;
  --primary-light: #2f6ba0;
  --accent: #3d7ab5;
  --bg-light: #f4f7fa;       /* 浅蓝灰背景 */
  --bg-white: #ffffff;
  --text: #2c3e50;
  --text-secondary: #5a6b7c;
  --border: #dde5ec;
  --shadow: 0 2px 12px rgba(31, 78, 121, 0.08);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  background: var(--bg-white);
  line-height: 1.7;
  font-size: 16px;
}

a {
  text-decoration: none;
  color: inherit;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------------- 顶部导航 ---------------- */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-white);
  border-bottom: 1px solid var(--border);
  box-shadow: 0 1px 6px rgba(31, 78, 121, 0.06);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 19px;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: 1px;
}

.nav-list {
  display: flex;
  list-style: none;
  gap: 32px;
}

.nav-list a {
  font-size: 15px;
  color: var(--text);
  transition: color 0.2s;
}

.nav-list a:hover {
  color: var(--primary);
}

.nav-toggle-label {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle-label span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--primary);
}

/* ---------------- 首页 Banner ---------------- */
.hero {
  background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 55%, var(--accent) 100%);
  color: #ffffff;
  padding: 120px 0;
  text-align: center;
}

.hero-title {
  font-size: 42px;
  font-weight: 700;
  letter-spacing: 3px;
  margin-bottom: 20px;
}

.hero-subtitle {
  font-size: 18px;
  color: #d6e4f1;
  letter-spacing: 1px;
}

/* ---------------- 通用区块 ---------------- */
.section {
  padding: 72px 0;
}

.section-alt {
  background: var(--bg-light);
}

.section-title {
  text-align: center;
  font-size: 30px;
  font-weight: 700;
  color: var(--primary-dark);
  letter-spacing: 2px;
}

.section-line {
  width: 56px;
  height: 3px;
  background: var(--accent);
  margin: 18px auto 40px;
  border-radius: 2px;
}

/* ---------------- 关于我们 ---------------- */
.about-text {
  max-width: 960px;
  margin: 0 auto;
  text-align: center;
  color: var(--text-secondary);
  font-size: 16px;
}

/* ---------------- 服务内容卡片（5 卡片：首卡通栏） ---------------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.card {
  background: var(--bg-white);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 28px 24px;
  box-shadow: var(--shadow);
  transition: transform 0.2s, box-shadow 0.2s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 6px 18px rgba(31, 78, 121, 0.12);
}

.card-wide {
  grid-column: 1 / -1;
  background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
  border: none;
  color: #ffffff;
}

.card-wide .card-title {
  color: #ffffff;
}

.card-wide .card-text {
  color: #dde9f5;
}

.card-link {
  display: inline-block;
  margin-top: 16px;
  padding: 10px 26px;
  background: #ffffff;
  color: var(--primary);
  border-radius: 6px;
  font-size: 14px;
  font-weight: 600;
  transition: background 0.2s;
}

.card-link:hover {
  background: #eaf2fa;
}

.card-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
}

.card-text {
  font-size: 14px;
  color: var(--text-secondary);
}

/* ---------------- 技术优势 ---------------- */
.adv-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.adv-item {
  text-align: center;
  padding: 32px 24px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  background: var(--bg-white);
  border-radius: 6px;
  box-shadow: var(--shadow);
}

.adv-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 10px;
}

.adv-text {
  font-size: 14px;
  color: var(--text-secondary);
}

/* ---------------- 联系我们 ---------------- */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.contact-heading {
  font-size: 18px;
  font-weight: 700;
  color: var(--primary-dark);
  margin-bottom: 20px;
}

.contact-list {
  list-style: none;
}

.contact-list li {
  display: flex;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
}

.contact-label {
  width: 100px;
  flex-shrink: 0;
  color: var(--text-secondary);
  font-size: 15px;
}

.contact-value {
  color: var(--text);
  font-size: 15px;
}

.contact-form .form-row {
  margin-bottom: 16px;
}

.form-input,
.form-textarea {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: 14px;
  font-family: inherit;
  color: var(--text);
  background: var(--bg-white);
  outline: none;
  transition: border-color 0.2s;
}

.form-input:focus,
.form-textarea:focus {
  border-color: var(--accent);
}

.form-textarea {
  resize: vertical;
}

.form-button {
  padding: 12px 32px;
  background: var(--primary);
  color: #ffffff;
  border: none;
  border-radius: 6px;
  font-size: 15px;
  cursor: not-allowed;
  opacity: 0.75;
}

/* ---------------- 页脚 ---------------- */
.footer {
  background: var(--primary-dark);
  color: #cfdae6;
  padding: 40px 0 36px;
  font-size: 14px;
}

.footer-inner {
  text-align: center;
}

.footer-copyright {
  color: #e8eef5;
  margin-bottom: 6px;
}

.footer-icp {
  margin-bottom: 16px;
  color: #b6c6d6;
}
.footer-icp a {
  color: inherit;
  text-decoration: none;
}
.footer-icp a:hover {
  text-decoration: underline;
}

.footer-disclaimer {
  max-width: 960px;
  margin: 0 auto;
  text-align: justify;
  font-size: 12px;
  line-height: 1.8;
  color: #9db0c2;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  padding-top: 16px;
}

/* ---------------- 响应式 ---------------- */
/* 平板 */
@media (max-width: 992px) {
  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 手机 */
@media (max-width: 768px) {
  .hero {
    padding: 80px 0;
  }

  .hero-title {
    font-size: 28px;
    letter-spacing: 2px;
  }

  .hero-subtitle {
    font-size: 15px;
  }

  .section {
    padding: 56px 0;
  }

  .section-title {
    font-size: 24px;
  }

  .card-grid,
  .adv-grid,
  .contact-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .card-wide {
    grid-column: auto;
  }

  /* 移动端导航（纯 CSS 汉堡菜单） */
  .nav-toggle-label {
    display: flex;
  }

  .nav {
    position: fixed;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--bg-white);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 6px 12px rgba(31, 78, 121, 0.08);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .nav-list {
    flex-direction: column;
    gap: 0;
    padding: 8px 0;
  }

  .nav-list li {
    border-bottom: 1px solid var(--bg-light);
  }

  .nav-list a {
    display: block;
    padding: 14px 24px;
    font-size: 16px;
  }

  .nav-toggle:checked ~ .nav {
    max-height: 320px;
  }

  .contact-list li {
    flex-direction: column;
    gap: 4px;
  }
}

/* 小屏手机 */
@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .hero-title {
    font-size: 24px;
  }

  .logo {
    font-size: 16px;
  }
}