/* ---------- 基础配色 ---------- */

:root {
  --bg: #f5f5f7;
  --bg-alt: #ffffff;
  --border: #e5e7eb;
  --text-main: #111827;
  --text-muted: #6b7280;
  --accent: #1d4ed8;
  --accent-soft: #e0ecff;
  --radius-lg: 16px;
  --radius-md: 12px;
  --shadow-soft: 0 12px 28px rgba(15, 23, 42, 0.08);
  --container-width: 1080px;
}

/* ---------- 全局重置 ---------- */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text",
    "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", sans-serif;
  background: var(--bg);
  color: var(--text-main);
  min-height: 100vh;
}

/* 链接 */

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* 容器 */

.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ---------- 顶部导航 ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

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

.logo {
  display: flex;
  flex-direction: column;
}

.logo-title {
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.logo-sub {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.main-nav {
  display: flex;
  gap: 1.25rem;
  font-size: 0.9rem;
}

.nav-link {
  color: var(--text-muted);
  position: relative;
  padding-bottom: 2px;
}

.nav-link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0%;
  height: 1px;
  background: var(--accent);
  transition: width 0.2s ease;
}

.nav-link:hover {
  color: var(--text-main);
}

.nav-link:hover::after {
  width: 100%;
}

/* 语言切换 */

.lang-switch {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.lang-btn {
  border: none;
  background: transparent;
  cursor: pointer;
  color: var(--text-muted);
  padding: 2px 4px;
}

.lang-btn.active {
  color: var(--accent);
  font-weight: 600;
}

.lang-divider {
  opacity: 0.5;
}

/* ---------- Section 通用 ---------- */

.section {
  padding: 3rem 0;
}

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

.section-title {
  font-size: 1.4rem;
  margin: 0 0 1.5rem;
}

/* ---------- Hero 区 ---------- */

.hero {
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(0, 1.1fr);
  gap: 2rem;
  align-items: flex-start;
}

.hero-title {
  font-size: 1.9rem;
  margin: 0 0 1rem;
}

.hero-lead {
  margin: 0 0 1.2rem;
  color: var(--text-muted);
  font-size: 0.98rem;
  line-height: 1.6;
}

.hero-lead strong {
  color: var(--text-main);
}

.hero-lead em {
  font-style: normal;
  font-weight: 500;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.8rem;
}

.meta-item {
  padding: 0.25rem 0.6rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: #ffffff;
  color: var(--text-muted);
}

/* Hero 右侧卡片 */

.hero-aside {
  display: flex;
  justify-content: flex-end;
}

.hero-card {
  background: #ffffff;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  padding: 1.2rem 1.2rem;
  box-shadow: var(--shadow-soft);
}

.hero-label {
  display: inline-block;
  padding: 0.2rem 0.7rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: #1e3a8a;
  font-size: 0.8rem;
  margin-bottom: 0.75rem;
}

.hero-list {
  margin: 0 0 0.8rem;
  padding-left: 1.1rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.hero-links {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.86rem;
}

/* ---------- Grid & Card ---------- */

.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.card {
  background: #ffffff;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  padding: 1rem 1.1rem;
  box-shadow: 0 8px 18px rgba(15, 23, 42, 0.04);
}

.card h3 {
  margin: 0 0 0.5rem;
  font-size: 1.02rem;
}

.card p {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.92rem;
  line-height: 1.6;
}

/* ---------- Publications ---------- */

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

.pub-list li {
  padding-left: 0.85rem;
  border-left: 2px solid var(--accent-soft);
  margin-bottom: 1rem;
}

.pub-year {
  display: inline-block;
  font-size: 0.78rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.1rem;
}

.pub-list p {
  margin: 0.1rem 0;
  font-size: 0.9rem;
  color: var(--text-main);
}

.pub-more {
  margin-top: 1.25rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* ---------- Contact ---------- */

.contact-card {
  background: #ffffff;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  padding: 1rem 1.1rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* ---------- Footer ---------- */

.site-footer {
  border-top: 1px solid var(--border);
  background: #ffffff;
  padding: 1rem 0 1.5rem;
}

.footer-inner {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---------- 语言显隐控制（重点修正） ---------- */

/* 默认：两种语言都显示，保证绝不会全白 */
.lang-zh,
.lang-en {
  display: block;
}

/* 当 body 标记为 zh 时，隐藏英文 */
body.lang-zh .lang-en {
  display: none !important;
}

/* 当 body 标记为 en 时，隐藏中文 */
body.lang-en .lang-zh {
  display: none !important;
}

/* ---------- 响应式 ---------- */

@media (max-width: 880px) {
  .nav-container {
    align-items: flex-start;
    padding-top: 0.5rem;
    padding-bottom: 0.5rem;
  }

  .main-nav {
    display: none; /* 小屏简化导航 */
  }

  .hero-inner {
    grid-template-columns: minmax(0, 1fr);
  }

  .hero-aside {
    justify-content: flex-start;
  }

  .grid-2 {
    grid-template-columns: minmax(0, 1fr);
  }
}