/* 基础变量与重置 */
:root {
  --bg: #ededed;
  --panel: #ffffff;
  --text: #ffffff;
  --muted: #ffffff;
  --primary: #0026ff;
  /*--border: #22304b;暂时删除*/ 
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: Inter, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Noto Sans", "PingFang SC", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
}

img { display: block; max-width: 100%; }
.container {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 16px;
}

/* 头部 */ /*  头部ID*/
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: #000000;
  border-bottom: 1px solid var(--border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.logo { font-weight: 800; letter-spacing: 0.5px; }
.logo img {
  height: 40px;
  width: auto;
  display: block;
}
.nav { display: none; gap: 20px; }
.nav a {
  color: var(--muted);
  text-decoration: none;
  font-weight: 600;
}
.nav a:hover { color: var(--text); }

/* 按钮 */
.btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 10px 16px;
  border-radius: 10px;
  cursor: pointer;
}
.btn.primary {
  background: var(--primary);
  border-color: var(--border);
}
.btn.ghost { background: transparent; }

/* 首屏 */
.hero {
  height: 900px;
  background-size: cover;
  background-position: center;
  position: relative;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgb(0, 0, 0);
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.4);
  z-index: 1;
}

.hero-inner {
  text-align: center;
  position: relative;
  z-index: 2;
}

/* 背景视频覆盖整个首屏 */
.hero-video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  z-index: 0;
}

.hero h1 { margin: 0 0 12px; font-size: 40px; letter-spacing: .3px; }
.subtitle { color: rgb(184, 37, 37); max-width: 720px; margin: 0 auto 20px; }
.actions { display: flex; gap: 12px; justify-content: center; }

/* 通用区块 */
.section { padding: 100px 0; }
.section.alt { border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-title { margin: 0 0 20px; font-size: 28px; color: #000000; }

/* 功能网格 */
.grid {
  display: grid;
  grid-template-columns: repeat(1, minmax(0, 1fr));
  gap: 16px;
}
.card {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  position: relative;
  min-height: 200px;
}
.card h3 { margin: 0 0 8px; color: #ffffff; text-shadow: 0 2px 4px rgba(0,0,0,0.5); }
.card p { margin: 0; color: #ffffff; text-shadow: 0 2px 4px rgba(0,0,0,0.5); }

/* 核心功能四个卡片底图 */
#features .card:nth-child(1) {
  background-image: url('img/OY7A0544.jpg');
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
}
#features .card:nth-child(2) {
  background-image: url('img/OY7A0551.jpg');
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
}
#features .card:nth-child(3) {
  background-image: url('img/OY7A0554.jpg');
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
}
#features .card:nth-child(4) {
  background-image: url('img/OY7A0571.jpg');
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
}

/* 关于区块左右结构 */
.split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
  align-items: center;
}
.list { margin: 12px 0 0; padding: 0 0 0 18px; color: var(--muted); }
.illustration {
  height: 220px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 16px;
}

/* 表单 */
.form { max-width: 640px; margin: 0 auto; }
.form-row { display: flex; flex-direction: column; gap: 8px; margin-bottom: 14px; }
label { color: var(--muted); font-weight: 600; }
input, textarea {
  width: 100%;
  padding: 12px 14px;
  background: #0e1629;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  outline: none;
}
input:focus, textarea:focus { border-color: var(--primary); }

/* 页脚 */
.site-footer { border-top: 1px solid var(--border); padding: 20px 0; margin-top: 20px; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.back-to-top { color: var(--muted); text-decoration: none; }
.back-to-top:hover { color: var(--text); }

/* 响应式 */
@media (min-width: 680px) {
  .nav { display: flex; }
  .hero { padding: 0; }
  .hero h1 { font-size: 52px; }
  .grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .split { grid-template-columns: 1.2fr 1fr; }
}

@media (min-width: 1000px) {
  .grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}