/*
  样式说明：
  - 使用CSS变量定义主题色与间距
  - 采用响应式布局，移动优先
  - 体现书法风格的字体与稳重配色
*/

:root {
  --color-bg: #ffffff;
  --color-text: #222222;
  --color-muted: #666666;
  --color-primary: #1f3b4d; /* 稳重蓝灰 */
  --color-accent: #8c6239;  /* 书法棕 */
  --color-border: #e6e6e6;
  --color-alt-bg: #fafafa;
  --max-width: 1080px;
  --radius: 10px;
  --space-1: 6px;
  --space-2: 12px;
  --space-3: 20px;
  --space-4: 28px;
  --space-5: 40px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "KaiTi", "STKaiti", "SimKai", "Noto Serif SC", "Songti SC", serif;
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.6;
}

img { max-width: 100%; display: block; }
a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { width: 92%; max-width: var(--max-width); margin: 0 auto; }
.text-center { text-align: center; }
.space { height: var(--space-4); }
.muted { color: var(--color-muted); }

/* Header & Nav */
.site-header {
  position: sticky; top: 0; z-index: 1000;
  background: rgba(255,255,255,0.96);
  backdrop-filter: saturate(1.1) blur(6px);
  border-bottom: 1px solid var(--color-border);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; padding: var(--space-2) 0; }
.logo { display: inline-flex; align-items: center; gap: var(--space-2); font-weight: bold; color: var(--color-text); }
.logo img { filter: grayscale(0.2); }
.logo-text { font-size: 16px; letter-spacing: 1px; }

.site-nav ul { list-style: none; margin: 0; padding: 0; display: flex; gap: var(--space-3); }
.site-nav a { padding: var(--space-2) var(--space-2); border-radius: 6px; }
.site-nav a[aria-current="page"] { background: var(--color-primary); color: #fff; }
.nav-toggle { display: none; }

/* Hero */
.hero { padding: var(--space-5) 0; background: linear-gradient(135deg, #ffffff 0%, #f9f9fb 50%, #ffffff 100%); }
.hero-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; align-items: center; gap: var(--space-4); }
.hero-text h1 { margin: 0 0 var(--space-2); font-size: 28px; color: var(--color-primary); }
.hero .subtitle { margin: 0 0 var(--space-3); color: var(--color-muted); }
.hero-actions { display: flex; gap: var(--space-2); flex-wrap: wrap; }

.page-hero.small { padding: var(--space-4) 0; background: var(--color-alt-bg); border-bottom: 1px solid var(--color-border); }
.page-hero h1 { margin: 0 0 var(--space-1); color: var(--color-primary); font-size: 24px; }
.page-hero .subtitle { color: var(--color-muted); }

/* Buttons */
.btn { display: inline-block; padding: 10px 16px; border-radius: 8px; border: 1px solid var(--color-border); transition: background .2s ease, color .2s ease, border-color .2s ease; }
.btn-primary { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.btn-primary:hover { opacity: .92; }
.btn-secondary { background: var(--color-accent); color: #fff; border-color: var(--color-accent); }
.btn-secondary:hover { opacity: .92; }
.btn-outline { background: transparent; color: var(--color-primary); }
.btn-outline:hover { border-color: var(--color-primary); }

.link { display: inline-block; margin-top: var(--space-2); }

/* Sections */
.section { padding: var(--space-5) 0; }
.section.alt { background: var(--color-alt-bg); border-top: 1px solid var(--color-border); border-bottom: 1px solid var(--color-border); }
.section-title { font-size: 20px; margin: 0 0 var(--space-2); color: var(--color-primary); }

/* Grid & Card */
.grid { display: grid; gap: var(--space-3); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-4); }

.card { background: #fff; padding: var(--space-3); border: 1px solid var(--color-border); border-radius: var(--radius); box-shadow: 0 1px 2px rgba(0,0,0,0.03); }
.card h3, .card h2 { margin-top: 0; }
.course p { margin: 6px 0; }
.teacher { text-align: center; }
.teacher img { margin: 0 auto var(--space-2); border-radius: 50%; border: 1px solid var(--color-border); }

/* Works */
.works-preview { margin-top: var(--space-3); }
.work-item { background: #fff; border: 1px solid var(--color-border); border-radius: var(--radius); overflow: hidden; }
.work-item img { width: 100%; height: auto; }
.work-item figcaption { padding: 10px; color: var(--color-muted); }
.works-gallery { align-items: start; }

/* Footer */
.site-footer { border-top: 1px solid var(--color-border); background: #fff; }
.footer-inner { padding: var(--space-4) 0; text-align: center; }

/* Back to top */
.back-to-top { position: fixed; right: 16px; bottom: 16px; width: 36px; height: 36px; border-radius: 18px; border: 1px solid var(--color-border); background: #fff; color: var(--color-primary); box-shadow: 0 2px 8px rgba(0,0,0,0.08); display: none; align-items: center; justify-content: center; }
.back-to-top:hover { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }

/* Contact map */
.map-box { border: 1px solid var(--color-border); border-radius: var(--radius); overflow: hidden; }

/* Responsive */
@media (max-width: 960px) {
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .hero-inner { grid-template-columns: 1fr; }
  .two-col { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .grid-3 { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
  .logo-text { display: none; }
  .nav-toggle { display: inline-block; padding: 8px 12px; border: 1px solid var(--color-border); border-radius: 8px; background: #fff; color: var(--color-primary); }
  .site-nav { position: absolute; left: 0; right: 0; top: 60px; background: #fff; border-bottom: 1px solid var(--color-border); display: none; }
  .site-nav.open { display: block; }
  .site-nav ul { flex-direction: column; gap: 0; }
  .site-nav a { display: block; padding: 12px var(--space-3); border-radius: 0; border-top: 1px solid var(--color-border); }
}