:root {
  --bg: #0B1437;
  --bg-alt: #0E1B45;
  --ink: #1a2238;
  --ink-soft: #5b6478;
  --line: #e7eaf2;
  --brand: #3b6cff;
  --brand-2: #6a4bff;
  --accent: #2bd4c4;
  --white: #ffffff;
  --radius: 16px;
  --shadow: 0 10px 30px rgba(16, 27, 69, .08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: #f6f8fc;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
.container { width: min(1140px, 92vw); margin: 0 auto; }
h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 .5em; }

/* 顶部导航 */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255, 255, 255, .9);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav { display: flex; align-items: center; gap: 24px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 18px; }
.brand-logo { height: 34px; width: auto; border-radius: 8px; object-fit: contain; }
.nav-links { display: flex; gap: 22px; margin-left: auto; font-size: 15px; color: var(--ink-soft); }
.nav-links a:hover { color: var(--brand); }
.nav-cta {
  padding: 9px 18px; border-radius: 999px; color: #fff; font-size: 14px;
  background: linear-gradient(135deg, var(--brand), var(--brand-2));
}
.nav-toggle { display: none; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav-toggle span { display: block; width: 22px; height: 2px; background: var(--ink); margin: 4px 0; transition: .3s; }

/* 按钮 */
.btn { display: inline-block; padding: 12px 26px; border-radius: 999px; font-size: 15px; font-weight: 600; transition: transform .15s, box-shadow .15s; }
.btn:hover { transform: translateY(-2px); }
.btn-primary { color: #fff; background: linear-gradient(135deg, var(--brand), var(--brand-2)); box-shadow: 0 8px 20px rgba(59, 108, 255, .35); }
.btn-ghost { color: #fff; border: 1px solid rgba(255, 255, 255, .6); }

/* 首屏 */
.hero { position: relative; color: #fff; overflow: hidden;
  background: radial-gradient(1200px 600px at 80% -10%, rgba(106, 75, 255, .45), transparent),
              radial-gradient(900px 500px at 0% 110%, rgba(43, 212, 196, .35), transparent),
              linear-gradient(160deg, var(--bg), var(--bg-alt)); }
.hero-inner { padding: 96px 0 84px; }
.hero-eyebrow { letter-spacing: 2px; color: var(--accent); font-size: 14px; margin: 0 0 14px; }
.hero-title { font-size: clamp(30px, 5vw, 52px); font-weight: 800; margin: 0 0 18px; }
.hero-sub { max-width: 640px; color: rgba(255, 255, 255, .82); font-size: 17px; margin: 0 0 28px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 44px; }
.hero-stats { display: flex; gap: 40px; flex-wrap: wrap; list-style: none; padding: 0; margin: 0; }
.hero-stats li { display: flex; flex-direction: column; }
.hero-stats strong { font-size: 26px; }
.hero-stats span { color: rgba(255, 255, 255, .7); font-size: 14px; }

/* 区块 */
.section { padding: 84px 0; }
.section-alt { background: #fff; }
.section-title { text-align: center; font-size: clamp(24px, 3.4vw, 34px); }
.section-title.light { color: #fff; text-align: left; }
.section-lead { text-align: center; max-width: 720px; margin: 0 auto 40px; color: var(--ink-soft); }
.section-lead.light { color: rgba(255, 255, 255, .82); text-align: left; margin-left: 0; }

/* 卡片网格 */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.grid-auto { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 18px; }
.card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; box-shadow: var(--shadow); }
.section-alt .card { background: #f6f8fc; }
.card h3 { color: var(--brand); }
.card p { margin: 0; color: var(--ink-soft); }

/* 技术栈说明行 */
.tech-line { text-align: center; color: var(--brand); font-weight: 600; margin-top: 28px; font-size: 15px; }

/* 开发案例卡 */
.card.case { display: flex; flex-direction: column; gap: 8px; }
.case-tag { align-self: flex-start; font-size: 12px; color: #fff; background: linear-gradient(135deg, var(--brand), var(--brand-2)); padding: 3px 10px; border-radius: 999px; margin-bottom: 2px; }
.case h3 { margin: 0; color: var(--ink); }
.case p { margin: 0; color: var(--ink-soft); }

/* 产品卡 */
.product { display: flex; flex-direction: column; gap: 10px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow); transition: transform .15s, box-shadow .15s; }
a.product:hover { transform: translateY(-4px); box-shadow: 0 16px 36px rgba(16, 27, 69, .14); }
.product-thumb { height: 150px; border-radius: 12px; overflow: hidden; background: linear-gradient(135deg, var(--brand), var(--brand-2)); }
.product-thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.product h3 { font-size: 18px; margin: 6px 0 0; }
.product p { color: var(--ink-soft); margin: 0; flex: 1; }
.product-more { color: var(--brand); font-weight: 600; font-size: 14px; }

/* 场景 chip */
.chip { background: #fff; border: 1px solid var(--line); border-radius: 14px; padding: 22px; box-shadow: var(--shadow); }
.chip h4 { color: var(--brand); margin: 0 0 6px; }
.chip p { margin: 0; color: var(--ink-soft); font-size: 14px; }

/* 新闻 */
.news-list { list-style: none; padding: 0; margin: 0 auto; max-width: 760px; }
.news-list li { display: flex; align-items: baseline; gap: 16px; padding: 16px 0; border-bottom: 1px solid var(--line); }
.news-date { color: var(--brand); font-weight: 600; flex: 0 0 70px; }
.news-list a:hover { color: var(--brand); }

/* 联系 */
.section-contact { background: linear-gradient(160deg, var(--bg), var(--bg-alt)); color: #fff; }
.contact-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: start; }
.contact-list { list-style: none; padding: 0; margin: 24px 0 0; display: grid; gap: 14px; }
.contact-list li { display: flex; gap: 14px; }
.contact-list span { color: rgba(255, 255, 255, .6); flex: 0 0 72px; }
.contact-list a { color: #fff; }
.contact-form { background: rgba(255, 255, 255, .06); border: 1px solid rgba(255, 255, 255, .14); border-radius: var(--radius); padding: 24px; display: grid; gap: 14px; }
.contact-form input, .contact-form textarea, .contact-form select { width: 100%; padding: 12px 14px; border-radius: 10px; border: 1px solid rgba(255, 255, 255, .18); background: rgba(255, 255, 255, .08); color: #fff; font: inherit; }
.contact-form input::placeholder, .contact-form textarea::placeholder { color: rgba(255, 255, 255, .55); }
/* 下拉框：清除浏览器默认外观，改为深色底 + 自绘箭头，避免出现白底黑字 */
.contact-form select {
  appearance: none;
  -webkit-appearance: none;
  -moz-appearance: none;
  cursor: pointer;
  padding-right: 42px;
  background-color: rgba(255, 255, 255, .08);
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='9' viewBox='0 0 14 9'%3E%3Cpath d='M1 1l6 6 6-6' fill='none' stroke='%23c9d3ea' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 16px center;
  -webkit-text-fill-color: #fff;
  text-overflow: ellipsis;
}
.contact-form select:focus { outline: none; border-color: rgba(255, 255, 255, .45); }
/* 展开面板由系统渲染，需单独设为深色文字浅色底，否则白字白底不可见 */
.contact-form select option { color: #1b2436; background: #fff; }
.contact-form .btn { justify-self: start; }
/* 表单状态提示：默认说明文案为灰色，校验失败红色、提交成功绿色 */
.form-tip { font-size: 12px; color: rgba(255, 255, 255, .6); margin: 0; min-height: 0; }
.form-tip.error { color: #ff8b8b; }
.form-tip.success { color: #6ee7a8; }

/* 页脚 */
.site-footer { background: #070d24; color: rgba(255, 255, 255, .8); padding: 36px 0; }
.footer-inner { display: flex; align-items: center; gap: 24px; flex-wrap: wrap; }
.footer-brand { display: flex; align-items: center; gap: 10px; font-weight: 700; }
.footer-links { display: flex; gap: 20px; margin-left: auto; }
.footer-links a:hover { color: var(--accent); }
.copyright { width: 100%; margin: 12px 0 0; font-size: 13px; color: rgba(255, 255, 255, .5); }
.copyright a { color: rgba(255, 255, 255, .7); }
.beian { width: 100%; margin: 4px 0 0; font-size: 13px; }
.beian a { color: rgba(255, 255, 255, .55); }
.beian a:hover { color: var(--accent); }

/* 响应式 */
@media (max-width: 900px) {
  .grid-3, .grid-4 { grid-template-columns: 1fr 1fr; }
  .contact-inner { grid-template-columns: 1fr; gap: 28px; }
  .nav-links { display: none; }
  .nav-toggle { display: block; margin-left: auto; }
  .nav-cta { display: none; }
  .site-header.open .nav-links { display: flex; position: absolute; top: 64px; left: 0; right: 0; flex-direction: column; gap: 0; background: #fff; border-bottom: 1px solid var(--line); padding: 8px 0; }
  .site-header.open .nav-links a { padding: 12px 6vw; }
}
@media (max-width: 560px) {
  .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .hero-stats { gap: 24px; }
}