/* ============================================================
   DDW 学术站 — 公共样式（追加层）
   依赖：style.css / bootstrap.min.css / fontawesome.all.min.css
   本文件追加中文字体栈 + 学术站专属区块样式
   ============================================================ */

:root {
  --ddw-primary: #0e4d8c;
  /* 学术深蓝 */
  --ddw-primary-dark: #0a3a6b;
  --ddw-accent: #1f8a70;
  /* 学术绿 */
  --ddw-gold: #c9a227;
  --ddw-bg-light: #f5f8fc;
  --ddw-text: #2b3a4a;
  --ddw-muted: #5b6b7b;
  --ddw-border: #e2e8f0;
}

/* 中文字体栈（Poppins 仅覆盖拉丁/数字，中文回退系统字体） */
body {
  font-family: "Poppins", "Microsoft YaHei", "PingFang SC", "Noto Sans SC", "Helvetica Neue", Arial, sans-serif;
  color: var(--ddw-text);
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-family: "Poppins", "Microsoft YaHei", "PingFang SC", "Noto Sans SC", sans-serif;
}

/* ---------- 学术站顶部条 ---------- */
.ddw-topbar {
  background: var(--ddw-primary);
  color: #fff;
  padding: 10px 0;
  font-size: 14px;
}

.ddw-topbar a {
  color: #fff;
}

.ddw-topbar .lang-switch {
  text-align: right;
}

.ddw-topbar .lang-switch a {
  display: inline-block;
  padding: 2px 12px;
  border: 1px solid rgba(255, 255, 255, .5);
  border-radius: 3px;
  margin-left: 6px;
  text-decoration: none;
  transition: background .2s;
}

.ddw-topbar .lang-switch a:hover {
  background: rgba(255, 255, 255, .15);
}

/* ---------- 学术站导航 ---------- */
.ddw-nav {
  background: #fff;
  border-bottom: 1px solid var(--ddw-border);
  box-shadow: 0 2px 8px rgba(14, 77, 140, .06);
}

.ddw-nav .navbar-brand {
  font-weight: 700;
  color: var(--ddw-primary);
  font-size: 22px;
}

.ddw-nav .navbar-brand small {
  display: block;
  font-size: 12px;
  font-weight: 400;
  color: var(--ddw-muted);
  letter-spacing: 1px;
}

.ddw-nav .nav-link {
  color: var(--ddw-text);
  font-weight: 500;
  font-size: 15px;
  padding: 12px 14px !important;
}

.ddw-nav .nav-link:hover,
.ddw-nav .nav-link.active {
  color: var(--ddw-primary);
}

/* ---------- 学术站页脚 ---------- */
.ddw-footer {
  background: #0b2540;
  color: #c7d4e2;
  padding: 50px 0 0;
  font-size: 14px;
}

.ddw-footer h5 {
  color: #fff;
  font-size: 16px;
  margin-bottom: 18px;
}

.ddw-footer p {
  color: #fff;
  margin-bottom: 18px;
}

.ddw-footer a {
  color: #c7d4e2;
  text-decoration: none;
}

.ddw-footer a:hover {
  color: #fff;
}

.ddw-footer .footer-links li {
  margin-bottom: 8px;
}

.ddw-footer .disclaimer {
  background: rgba(255, 255, 255, .06);
  border-left: 3px solid var(--ddw-gold);
  padding: 14px 18px;
  margin: 24px 0;
  font-size: 13px;
  line-height: 1.7;
}

.ddw-footer .disclaimer strong {
  color: var(--ddw-gold);
}

.ddw-footer .footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, .12);
  padding: 16px 0;
  margin-top: 30px;
  font-size: 13px;
  color: #8fa3b8;
}

/* ---------- 页面 Hero ---------- */
.ddw-hero {
  background: linear-gradient(135deg, var(--ddw-primary) 0%, var(--ddw-primary-dark) 100%);
  color: #fff;
  padding: 70px 0 60px;
  position: relative;
  overflow: hidden;
}

.ddw-hero .eyebrow {
  color: var(--ddw-gold);
  letter-spacing: 3px;
  text-transform: uppercase;
  font-size: 13px;
  font-weight: 600;
}

.ddw-hero h1 {
  font-size: 40px;
  font-weight: 700;
  margin: 12px 0 16px;
  color: #fff;
  line-height: 1.3;
}

.ddw-hero p {
  font-size: 17px;
  opacity: .92;
  max-width: 720px;
  line-height: 1.8;
  color: #fff;
}

.ddw-hero .breadcrumb {
  background: transparent;
  margin: 16px 0 0;
}

.ddw-hero .breadcrumb a,
.ddw-hero .breadcrumb-item {
  color: rgba(255, 255, 255, .8);
}

.ddw-hero .breadcrumb-item.active {
  color: #fff;
}

.ddw-hero .breadcrumb-item+.breadcrumb-item::before {
  color: rgba(255, 255, 255, .5);
}

/* ---------- 区块通用 ---------- */
.ddw-section {
  padding: 60px 0;
}

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

.ddw-section .section-title {
  font-size: 30px;
  font-weight: 700;
  color: var(--ddw-primary);
  margin-bottom: 12px;
}

.ddw-section .section-eyebrow {
  color: var(--ddw-accent);
  letter-spacing: 2px;
  font-size: 13px;
  font-weight: 600;
  text-transform: uppercase;
}

.ddw-section .section-sub {
  color: var(--ddw-muted);
  max-width: 760px;
  line-height: 1.8;
  margin-bottom: 30px;
}

/* ---------- 首页 Hero ---------- */
.ddw-home-hero {
  background: linear-gradient(135deg, #0a3a6b 0%, #0e4d8c 55%, #1565a8 100%);
  color: #fff !important;
  padding: 110px 0 90px;
  position: relative;
}

.ddw-home-hero h1 {
  font-size: 46px;
  font-weight: 700;
  color: #fff;
  line-height: 1.3;
}

.ddw-home-hero p {
  color: #fff;
}

.ddw-home-hero .lead {
  font-size: 19px;
  opacity: .92;
  max-width: 680px;
  line-height: 1.9;
  margin-top: 18px;
}

.ddw-home-hero .hero-cta {
  margin-top: 30px;
}

.ddw-home-hero .btn-ddw {
  background: var(--ddw-gold);
  color: #0b2540;
  font-weight: 600;
  padding: 12px 28px;
  border-radius: 4px;
  text-decoration: none;
  display: inline-block;
  transition: transform .2s, box-shadow .2s;
}

.ddw-home-hero .btn-ddw:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(0, 0, 0, .25);
}

/* ---------- 核心数据条 ---------- */
.ddw-stats {
  background: #fff;
  border-bottom: 1px solid var(--ddw-border);
  padding: 40px 0;
}

.ddw-stat {
  text-align: center;
  padding: 20px;
}

.ddw-stat .num {
  font-size: 46px;
  font-weight: 700;
  color: var(--ddw-primary);
  line-height: 1;
}

.ddw-stat .label {
  color: var(--ddw-muted);
  font-size: 15px;
  margin-top: 10px;
  line-height: 1.6;
}

/* ---------- 四宫格 / 卡片 ---------- */
.ddw-grid-card {
  background: #fff;
  border: 1px solid var(--ddw-border);
  border-radius: 8px;
  padding: 28px;
  height: 100%;
  transition: transform .25s, box-shadow .25s;
}

.ddw-grid-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 24px rgba(14, 77, 140, .12);
}

.ddw-grid-card .icon {
  font-size: 34px;
  color: var(--ddw-accent);
  margin-bottom: 14px;
}

.ddw-grid-card h3 {
  font-size: 19px;
  font-weight: 600;
  color: var(--ddw-primary);
  margin-bottom: 10px;
}

.ddw-grid-card p {
  color: var(--ddw-muted);
  font-size: 14px;
  line-height: 1.8;
}

.ddw-grid-card a.card-link {
  color: var(--ddw-primary);
  font-weight: 600;
  text-decoration: none;
}

/* ---------- 专家证言卡 ---------- */
.ddw-quote-card {
  background: #fff;
  border: 1px solid var(--ddw-border);
  border-radius: 8px;
  padding: 26px;
  height: 100%;
  position: relative;
}

.ddw-quote-card .quote-mark {
  color: var(--ddw-gold);
  font-size: 40px;
  line-height: 1;
  opacity: .5;
}

.ddw-quote-card .quote {
  font-size: 15px;
  line-height: 1.8;
  color: var(--ddw-text);
  margin: 12px 0 18px;
  font-style: italic;
}

.ddw-quote-card .expert {
  display: flex;
  align-items: center;
}

.ddw-quote-card .expert img {
  width: 52px;
  height: 52px;
  border-radius: 50%;
  object-fit: cover;
  margin-right: 14px;
  border: 2px solid var(--ddw-border);
}

.ddw-quote-card .expert .name {
  font-weight: 600;
  color: var(--ddw-primary);
}

.ddw-quote-card .expert .role {
  font-size: 13px;
  color: var(--ddw-muted);
}

/* ---------- 时间轴 ---------- */
.ddw-timeline {
  position: relative;
  padding-left: 30px;
}

.ddw-timeline::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--ddw-border);
}

.ddw-timeline .tl-item {
  position: relative;
  margin-bottom: 26px;
}

.ddw-timeline .tl-item::before {
  content: "";
  position: absolute;
  left: -30px;
  top: 6px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--ddw-accent);
  border: 3px solid #fff;
  box-shadow: 0 0 0 2px var(--ddw-accent);
}

.ddw-timeline .tl-year {
  font-weight: 700;
  color: var(--ddw-primary);
  font-size: 16px;
}

.ddw-timeline .tl-title {
  font-weight: 600;
  margin: 4px 0;
}

.ddw-timeline .tl-desc {
  color: var(--ddw-muted);
  font-size: 14px;
  line-height: 1.7;
}

/* ---------- FAQ 折叠 ---------- */
.ddw-faq .card {
  border: 1px solid var(--ddw-border);
  margin-bottom: 12px;
  border-radius: 6px;
}

.ddw-faq .card-header {
  background: #fff;
  padding: 0;
}

.ddw-faq .card-header .btn {
  width: 100%;
  text-align: left;
  font-weight: 600;
  color: var(--ddw-primary);
  padding: 16px 20px;
  text-decoration: none;
  font-size: 15px;
}

.ddw-faq .card-header .btn .fa {
  float: right;
  color: var(--ddw-accent);
}

.ddw-faq .card-body {
  color: var(--ddw-muted);
  line-height: 1.8;
  font-size: 14px;
}

/* ---------- 论文列表 ---------- */
.ddw-paper {
  background: #fff;
  border: 1px solid var(--ddw-border);
  border-left: 4px solid var(--ddw-accent);
  border-radius: 6px;
  padding: 18px 22px;
  margin-bottom: 14px;
}

.ddw-paper .paper-year {
  display: inline-block;
  background: var(--ddw-primary);
  color: #fff;
  font-size: 12px;
  padding: 2px 10px;
  border-radius: 3px;
  margin-right: 8px;
}

.ddw-paper .paper-title {
  font-weight: 600;
  color: var(--ddw-text);
  font-size: 15px;
}

.ddw-paper .paper-meta {
  color: var(--ddw-muted);
  font-size: 13px;
  margin-top: 6px;
  line-height: 1.7;
}

.ddw-paper .paper-links {
  margin-top: 8px;
}

.ddw-paper .paper-links a {
  font-size: 13px;
  margin-right: 14px;
  color: var(--ddw-primary);
  text-decoration: none;
}

/* ---------- 图书卡 ---------- */
.ddw-book {
  background: #fff;
  border: 1px solid var(--ddw-border);
  border-radius: 8px;
  overflow: hidden;
  height: 100%;
  transition: transform .25s, box-shadow .25s;
}

.ddw-book:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 24px rgba(14, 77, 140, .12);
}

.ddw-book .book-cover {
  height: 300px;
  background: linear-gradient(135deg, var(--ddw-primary), var(--ddw-accent));
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: 22px;
  text-align: center;
  padding: 20px;
}

.ddw-book .book-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.ddw-book .book-body {
  padding: 22px;
}

.ddw-book .book-body h3 {
  font-size: 18px;
  font-weight: 600;
  color: var(--ddw-primary);
}

.ddw-book .book-body .publisher {
  color: var(--ddw-muted);
  font-size: 13px;
  margin: 6px 0 12px;
}

.ddw-book .book-body p {
  color: var(--ddw-muted);
  font-size: 14px;
  line-height: 1.8;
}

/* ---------- 联系信息卡 ---------- */
.ddw-contact-card {
  background: #fff;
  border: 1px solid var(--ddw-border);
  border-radius: 8px;
  padding: 26px;
  height: 100%;
  text-align: center;
}

.ddw-contact-card .icon {
  font-size: 32px;
  color: var(--ddw-accent);
  margin-bottom: 12px;
}

.ddw-contact-card h4 {
  font-size: 16px;
  font-weight: 600;
  color: var(--ddw-primary);
}

.ddw-contact-card p {
  color: var(--ddw-muted);
  font-size: 14px;
  margin: 8px 0 0;
  line-height: 1.7;
}

/* ---------- 学术声明强调块 ---------- */
.ddw-note {
  background: #fff8e6;
  border: 1px solid #f0e0b0;
  border-left: 4px solid var(--ddw-gold);
  padding: 16px 20px;
  border-radius: 4px;
  font-size: 14px;
  line-height: 1.8;
  color: #6b5a1e;
  margin: 24px 0;
}

/* ---------- 数据表格 ---------- */
.ddw-table {
  width: 100%;
  border-collapse: collapse;
  margin: 20px 0;
}

.ddw-table th,
.ddw-table td {
  border: 1px solid var(--ddw-border);
  padding: 12px 16px;
  text-align: left;
  font-size: 14px;
}

.ddw-table th {
  background: var(--ddw-primary);
  color: #fff;
  font-weight: 600;
}

.ddw-table tr:nth-child(even) {
  background: var(--ddw-bg-light);
}

/* ---------- 响应式 ---------- */
@media (max-width: 768px) {
  .ddw-home-hero h1 {
    font-size: 32px;
  }

  .ddw-hero h1 {
    font-size: 30px;
  }

  .ddw-section {
    padding: 40px 0;
  }

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

  .ddw-stat .num {
    font-size: 36px;
  }
}