/* ===== 全局重置与变量 ===== */
:root {
  --c-bg: #F5F5F7;
  --c-surface: #FFFFFF;
  --c-primary: #2B5DAE;
  --c-primary-light: #E8F0FE;
  --c-accent: #1B8A5A;
  --c-accent-light: #E6F3DE;
  --c-text: #1D1D1F;
  --c-text-sec: #6E6E73;
  --c-border: #E5E5EA;
  --c-hero-bg: #1A1A2E;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 2px 12px rgba(0,0,0,0.06);
  --shadow-hover: 0 6px 24px rgba(0,0,0,0.10);
  --transition: 0.2s ease;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--c-bg);
  color: var(--c-text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--c-primary); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; display: block; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 20px; }

/* ===== 导航栏 ===== */
.navbar {
  background: var(--c-surface);
  border-bottom: 1px solid var(--c-border);
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(12px);
  background: rgba(255,255,255,0.92);
}
.nav-inner {
  max-width: 1100px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; justify-content: space-between;
  height: 56px;
}
.logo {
  font-size: 18px; font-weight: 700; color: var(--c-primary);
  letter-spacing: 1px;
}
.logo:hover { text-decoration: none; }
.nav-toggle {
  display: none; background: none; border: none;
  font-size: 22px; cursor: pointer; color: var(--c-text);
}
.nav-links { display: flex; gap: 28px; list-style: none; }
.nav-links a {
  font-size: 14px; color: var(--c-text-sec); font-weight: 500;
  transition: color var(--transition);
  padding: 4px 0; position: relative;
}
.nav-links a:hover { color: var(--c-primary); text-decoration: none; }
.nav-links a.active { color: var(--c-primary); }
.nav-links a.active::after {
  content: ""; position: absolute; bottom: -2px; left: 0; right: 0;
  height: 2px; background: var(--c-primary); border-radius: 1px;
}

/* ===== Hero ===== */
.hero {
  background: var(--c-hero-bg);
  color: #fff;
  padding: 80px 20px 64px;
  text-align: center;
}
.hero h1 {
  font-size: 36px; font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: 1px;
}
.hero-desc {
  font-size: 16px; color: rgba(255,255,255,0.7);
  margin-bottom: 32px;
}
.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 10px 28px;
  border-radius: 24px; font-size: 14px; font-weight: 600;
  transition: all var(--transition); cursor: pointer;
}
.btn-primary {
  background: var(--c-primary); color: #fff;
}
.btn-primary:hover { background: #1E4A8C; text-decoration: none; }
.btn-outline {
  border: 1.5px solid rgba(255,255,255,0.5); color: #fff;
}
.btn-outline:hover { background: rgba(255,255,255,0.1); text-decoration: none; }

/* ===== Stats ===== */
.stats { padding: 40px 20px; }
.stats-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px;
}
.stat-card {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 24px 16px;
  text-align: center;
  box-shadow: var(--shadow);
}
.stat-num {
  font-size: 32px; font-weight: 700; color: var(--c-primary);
}
.stat-label { font-size: 13px; color: var(--c-text-sec); margin-top: 4px; }

/* ===== Section ===== */
.section { padding: 56px 0; }
.section-alt { background: var(--c-surface); }
.section-title {
  font-size: 22px; font-weight: 700;
  margin-bottom: 28px;
  padding-left: 12px;
  border-left: 4px solid var(--c-primary);
}

/* ===== Card Grid ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}
.card {
  background: var(--c-surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: box-shadow var(--transition), transform var(--transition);
}
.card:hover { box-shadow: var(--shadow-hover); transform: translateY(-2px); text-decoration: none; display: block; }
.card-thumb {
  width: 100%; height: 170px; object-fit: cover;
  background: var(--c-primary-light);
  display: flex; align-items: center; justify-content: center;
  color: var(--c-primary); font-size: 48px;
}
.card-body { padding: 16px; }
.card-title { font-size: 15px; font-weight: 600; margin-bottom: 6px; color: var(--c-text); }
.card-meta { font-size: 12px; color: var(--c-text-sec); }
.card-tag {
  display: inline-block; font-size: 11px;
  background: var(--c-primary-light); color: var(--c-primary);
  padding: 2px 8px; border-radius: 4px; margin-top: 8px;
}

/* ===== Feature Grid (首页) ===== */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.feature-card {
  background: var(--c-bg);
  border-radius: var(--radius);
  padding: 32px 24px;
  display: block;
  transition: all var(--transition);
  border: 1px solid transparent;
}
.feature-card:hover { text-decoration: none; background: var(--c-surface); border-color: var(--c-border); box-shadow: var(--shadow); }
.feature-icon { font-size: 36px; margin-bottom: 16px; }
.feature-card h3 { font-size: 16px; font-weight: 600; margin-bottom: 8px; color: var(--c-text); }
.feature-card p { font-size: 13px; color: var(--c-text-sec); line-height: 1.7; }

/* ===== 视频列表页 ===== */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
}
.video-card {
  background: var(--c-surface);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: box-shadow var(--transition);
  cursor: pointer;
}
.video-card:hover { box-shadow: var(--shadow-hover); }
.video-thumb {
  position: relative; width: 100%; height: 180px;
  background: #0a0a0a; display: flex; align-items: center; justify-content: center;
}
.video-thumb .play-btn {
  width: 56px; height: 56px; border-radius: 50%;
  background: rgba(255,255,255,0.15); backdrop-filter: blur(4px);
  display: flex; align-items: center; justify-content: center;
  color: #fff; font-size: 24px; border: none; cursor: pointer;
  transition: background var(--transition);
}
.video-thumb .play-btn:hover { background: rgba(255,255,255,0.25); }
.video-info { padding: 16px; }
.video-info h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.video-info .meta { font-size: 12px; color: var(--c-text-sec); }
.video-info .desc { font-size: 13px; color: var(--c-text-sec); margin-top: 8px; line-height: 1.6; }

/* ===== 模型下载页 ===== */
.model-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
}
.model-card {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  transition: box-shadow var(--transition);
}
.model-card:hover { box-shadow: var(--shadow-hover); }
.model-icon { font-size: 40px; margin-bottom: 12px; }
.model-card h3 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.model-card .meta { font-size: 12px; color: var(--c-text-sec); margin-bottom: 10px; }
.model-card .desc { font-size: 13px; color: var(--c-text-sec); line-height: 1.6; margin-bottom: 14px; }
.btn-download {
  display: inline-block; padding: 8px 20px;
  background: var(--c-accent); color: #fff;
  border-radius: 20px; font-size: 13px; font-weight: 600;
  transition: background var(--transition);
}
.btn-download:hover { background: #146E47; text-decoration: none; color: #fff; }

/* ===== 教程列表页 ===== */
.tutorial-list { display: flex; flex-direction: column; gap: 16px; }
.tutorial-item {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  transition: box-shadow var(--transition);
  display: block;
}
.tutorial-item:hover { box-shadow: var(--shadow-hover); text-decoration: none; }
.tutorial-item h3 { font-size: 16px; font-weight: 600; color: var(--c-text); margin-bottom: 8px; }
.tutorial-item .summary { font-size: 13px; color: var(--c-text-sec); line-height: 1.7; }
.tutorial-item .meta { font-size: 12px; color: var(--c-text-sec); margin-top: 10px; }

/* ===== 关于页 ===== */
.about-section { max-width: 720px; margin: 0 auto; }
.about-section h2 { font-size: 20px; font-weight: 700; margin: 36px 0 16px; }
.about-section p, .about-section li {
  font-size: 14px; color: var(--c-text-sec); line-height: 1.8;
}
.about-section ul { padding-left: 20px; }
.about-section .highlight {
  background: var(--c-primary-light);
  border-radius: var(--radius-sm);
  padding: 20px; margin: 24px 0;
}
.tag-list { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.tag {
  font-size: 12px; padding: 4px 12px;
  background: var(--c-bg); border-radius: 16px;
  color: var(--c-text-sec);
}

/* ===== 筛选栏 ===== */
.filter-bar {
  display: flex; gap: 10px; flex-wrap: wrap;
  margin-bottom: 24px;
}
.filter-btn {
  padding: 6px 16px; border-radius: 20px;
  font-size: 13px; border: 1px solid var(--c-border);
  background: var(--c-surface); cursor: pointer;
  transition: all var(--transition);
}
.filter-btn:hover { border-color: var(--c-primary); color: var(--c-primary); }
.filter-btn.active { background: var(--c-primary); color: #fff; border-color: var(--c-primary); }

/* ===== 搜索框 ===== */
.search-box {
  width: 100%; max-width: 400px;
  padding: 10px 16px;
  border: 1px solid var(--c-border);
  border-radius: 24px;
  font-size: 14px;
  outline: none;
  transition: border-color var(--transition);
  margin-bottom: 24px;
}
.search-box:focus { border-color: var(--c-primary); }

/* ===== Footer ===== */
.footer {
  background: var(--c-hero-bg); color: rgba(255,255,255,0.6);
  padding: 32px 20px; font-size: 13px;
}
.footer-inner {
  max-width: 1100px; margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 16px;
}
.footer-logo { font-size: 16px; font-weight: 700; color: #fff; margin-bottom: 4px; }
.footer a { color: rgba(255,255,255,0.7); }
.footer a:hover { color: #fff; }

/* ===== 响应式 ===== */
@media (max-width: 768px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none; flex-direction: column;
    position: absolute; top: 56px; left: 0; right: 0;
    background: var(--c-surface);
    padding: 16px 20px;
    border-bottom: 1px solid var(--c-border);
    gap: 12px;
  }
  .nav-links.open { display: flex; }
  .hero h1 { font-size: 26px; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .card-grid, .video-grid, .model-grid {
    grid-template-columns: 1fr;
  }
  .footer-inner { flex-direction: column; text-align: center; }
}
@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .hero { padding: 56px 16px 48px; }
}

/* ===== 社区页面 ===== */
.hero-small {
  padding: 40px 20px 32px;
}
.hero-small h1 { font-size: 28px; margin-bottom: 8px; }

/* 工具栏 */
.community-toolbar {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 20px; flex-wrap: wrap;
}
.community-search { flex: 1; min-width: 200px; margin-bottom: 0; }
.btn-ask {
  border-radius: 24px; white-space: nowrap; flex-shrink: 0;
}

/* 话题列表 */
.topic-list { display: flex; flex-direction: column; gap: 14px; }
.topic-card {
  background: var(--c-surface);
  border-radius: var(--radius);
  padding: 20px 24px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: all var(--transition);
  border-left: 4px solid transparent;
  position: relative;
}
.topic-card:hover {
  box-shadow: var(--shadow-hover);
  transform: translateX(4px);
  border-left-color: var(--c-primary);
}
.topic-card.solved { border-left-color: var(--c-accent); }

.topic-card-header {
  display: flex; justify-content: space-between; align-items: flex-start;
  margin-bottom: 10px;
  gap: 12px;
}
.topic-card-title {
  font-size: 16px; font-weight: 600; color: var(--c-text);
  line-height: 1.5; flex: 1;
}
.topic-badge {
  display: inline-flex; align-items: center; gap: 4px;
  font-size: 11px; font-weight: 600; padding: 3px 10px;
  border-radius: 12px; white-space: nowrap; flex-shrink: 0;
}
.badge-hot { background: #FEF3E0; color: #C45D00; }
.badge-new { background: #E8F0FE; color: #2B5DAE; }
.badge-solved { background: #E6F3DE; color: #1B8A5A; }

.topic-card-body {
  font-size: 14px; color: var(--c-text-sec);
  line-height: 1.7; margin-bottom: 12px;
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical;
  overflow: hidden;
}

.topic-card-footer {
  display: flex; align-items: center; gap: 16px;
  font-size: 12px; color: var(--c-text-sec);
}
.topic-tag {
  background: var(--c-primary-light); color: var(--c-primary);
  padding: 2px 10px; border-radius: 10px; font-weight: 500;
}
.topic-meta { display: flex; align-items: center; gap: 4px; }
.topic-replies {
  margin-left: auto;
  background: var(--c-bg); padding: 2px 10px;
  border-radius: 10px;
}

/* 社区提示 */
.community-notice {
  text-align: center; padding: 28px 20px;
  color: var(--c-text-sec); font-size: 13px;
  background: var(--c-surface); border-radius: var(--radius);
  margin-top: 32px;
}

/* ===== 弹窗（提问/详情）===== */
.modal-overlay {
  display: none; position: fixed;
  inset: 0; z-index: 1000;
  background: rgba(0,0,0,0.5);
  backdrop-filter: blur(4px);
  align-items: center; justify-content: center;
  padding: 20px;
}
.modal-overlay.active { display: flex; }
.modal-card {
  background: var(--c-surface);
  border-radius: var(--radius);
  width: 100%; max-width: 560px;
  max-height: 90vh; overflow-y: auto;
  box-shadow: 0 20px 60px rgba(0,0,0,0.2);
  animation: modalIn 0.25s ease;
}
.modal-large { max-width: 720px; }
@keyframes modalIn {
  from { opacity: 0; transform: translateY(20px) scale(0.97); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}
.modal-header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 20px 24px; border-bottom: 1px solid var(--c-border);
  position: sticky; top: 0; background: var(--c-surface); z-index: 1;
}
.modal-header h2 { font-size: 18px; font-weight: 700; }
.modal-close {
  background: none; border: none; font-size: 26px; cursor: pointer;
  color: var(--c-text-sec); line-height: 1; padding: 4px;
}
.modal-close:hover { color: var(--c-text); }
.modal-body { padding: 24px; }

/* 表单样式 */
.form-label {
  display: block; font-size: 13px; font-weight: 600;
  color: var(--c-text); margin-bottom: 6px; margin-top: 16px;
}
.form-label:first-child { margin-top: 0; }
.required { color: #D93025; }
.form-input, .form-select, .form-textarea {
  width: 100%; padding: 10px 14px;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  font-size: 14px; font-family: inherit;
  outline: none; transition: border-color var(--transition);
  background: var(--c-bg);
}
.form-input:focus, .form-select:focus, .form-textarea:focus {
  border-color: var(--c-primary); box-shadow: 0 0 0 3px var(--c-primary-light);
}
.form-textarea { resize: vertical; min-height: 100px; }
.form-actions {
  display: flex; gap: 10px; margin-top: 24px; justify-content: flex-end;
}
.btn-cancel { border-color: var(--c-border); color: var(--c-text-sec); }

/* 上传区域 */
.form-upload {
  border: 2px dashed var(--c-border); border-radius: var(--radius-sm);
  padding: 20px; text-align: center;
  cursor: pointer; transition: all var(--transition);
}
.form-upload:hover { border-color: var(--c-primary); background: var(--c-primary-light); }
.upload-placeholder { font-size: 13px; color: var(--c-text-sec); }
.upload-preview { margin-top: 12px; }
.upload-preview img {
  max-width: 200px; max-height: 150px;
  border-radius: var(--radius-sm); object-fit: cover;
}

/* ===== Giscus / 留言区 ===== */
.giscus-wrap { margin-top: 10px; }
.giscus-placeholder { min-height: 300px; }
.giscus-fallback {
  background: var(--c-bg); border-radius: var(--radius);
  padding: 36px 28px; text-align: center;
  border: 1px dashed var(--c-border);
}
.giscus-fallback h3 { font-size: 18px; margin-bottom: 12px; color: var(--c-text); }
.giscus-fallback p { font-size: 13px; color: var(--c-text-sec); line-height: 1.7; margin-bottom: 8px; }
.giscus-fallback ul { list-style: none; padding: 0; text-align: left; max-width: 320px; margin: 12px auto; }
.giscus-fallback li {
  font-size: 13px; color: var(--c-text-sec); padding: 6px 0;
  border-bottom: 1px solid var(--c-border);
}
.fallback-form {
  margin-top: 24px; padding-top: 20px;
  border-top: 1px solid var(--c-border);
}
.fallback-form h4 { font-size: 15px; margin-bottom: 12px; color: var(--c-text); }
.fallback-form textarea {
  width: 100%; padding: 12px; border: 1px solid var(--c-border);
  border-radius: var(--radius-sm); font-size: 14px; font-family: inherit;
  resize: vertical; outline: none; background: var(--c-surface);
}
.fallback-form textarea:focus { border-color: var(--c-primary); }

/* 快速留言列表 */
.quick-msg-item {
  text-align: left; background: var(--c-surface);
  border-radius: var(--radius-sm); padding: 12px 16px;
  margin-top: 10px; font-size: 13px;
  box-shadow: var(--shadow);
}
.quick-msg-item .msg-text { color: var(--c-text); line-height: 1.6; }
.quick-msg-item .msg-time {
  font-size: 11px; color: var(--c-text-sec); margin-top: 6px;
}

/* ===== 学员案例展示 ===== */
.showcase-section {
  background: #0D0D12;
  padding: 56px 0;
}
.showcase-title {
  font-size: 28px; font-weight: 700;
  color: #fff; margin-bottom: 8px;
}
.showcase-subtitle {
  font-size: 14px; color: rgba(255,255,255,0.5);
  margin-bottom: 36px;
}
.showcase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 20px;
}
.showcase-card {
  background: #1A1A24;
  border-radius: 16px;
  overflow: hidden;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition);
  border: 1px solid rgba(255,255,255,0.06);
}
.showcase-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(0,0,0,0.4);
}
.showcase-img {
  width: 100%; aspect-ratio: 4/3;
  position: relative;
}
.showcase-img-placeholder {
  width: 100%; height: 100%;
  display: flex; align-items: center; justify-content: center;
  font-size: 48px;
}
.showcase-body {
  padding: 16px 18px 20px;
}
.showcase-body h3 {
  font-size: 15px; font-weight: 600;
  color: #fff; margin-bottom: 6px;
}
.showcase-body p {
  font-size: 13px; color: rgba(255,255,255,0.45);
  line-height: 1.6;
}

/* ===== 话题详情弹窗内容 ===== */
.detail-meta-row {
  display: flex; align-items: center; gap: 12px;
  flex-wrap: wrap; margin-bottom: 18px;
}
.detail-content {
  font-size: 14px; color: var(--c-text);
  line-height: 1.9; margin-bottom: 24px;
  white-space: pre-wrap;
}
.detail-content img {
  max-width: 100%; border-radius: var(--radius-sm);
  margin: 12px 0;
}
.reply-section { border-top: 1px solid var(--c-border); padding-top: 20px; }
.reply-section h3 { font-size: 16px; margin-bottom: 14px; }
.reply-item {
  background: var(--c-bg); border-radius: var(--radius-sm);
  padding: 14px 16px; margin-bottom: 10px;
}
.reply-author { font-weight: 600; font-size: 13px; color: var(--c-primary); }
.reply-time { font-size: 11px; color: var(--c-text-sec); margin-left: 8px; }
.reply-text { font-size: 13px; color: var(--c-text-sec); line-height: 1.7; margin-top: 6px; }
.reply-form {
  display: flex; gap: 8px; margin-top: 16px; align-items: flex-start;
}
.reply-form textarea {
  flex: 1; padding: 10px 14px; border: 1px solid var(--c-border);
  border-radius: var(--radius-sm); font-size: 13px;
  font-family: inherit; resize: none; height: 72px;
  outline: none; background: var(--c-surface);
}
.reply-form textarea:focus { border-color: var(--c-primary); }
.reply-form button { flex-shrink: 0; border-radius: 20px; }