/* ============================================================
   ShareLink · 全新UI设计
   风格：毛玻璃卡片 + 柔和渐变背景
   参考：Send.Wang / 私传网
   ============================================================ */

:root {
  /* 品牌色 */
  --brand: #ff6a3d;
  --brand-light: #ff8c5a;
  --brand-glow: rgba(255, 106, 61, 0.15);

  /* 文字 */
  --ink: #1e293b;
  --ink-2: #475569;
  --ink-3: #94a3b8;
  --ink-4: #cbd5e1;

  /* 背景 */
  --bg-warm: #fef9f3;
  --bg-cool: #f0f5ff;
  --card-bg: rgba(255, 255, 255, 0.82);
  --card-border: rgba(255, 255, 255, 0.65);

  /* 功能色 */
  --ok: #22c55e;
  --ok-bg: rgba(34, 197, 94, 0.1);
  --warn: #f59e0b;
  --warn-bg: rgba(245, 158, 11, 0.1);
  --err: #ef4444;

  /* 圆角 */
  --r-xl: 24px;
  --r-lg: 18px;
  --r-md: 14px;
  --r-sm: 10px;
  --r-xs: 8px;

  /* 阴影 */
  --shadow-card: 0 8px 32px rgba(30, 41, 59, 0.08), 0 2px 8px rgba(30, 41, 59, 0.04);
  --shadow-card-hover: 0 12px 40px rgba(30, 41, 59, 0.12), 0 4px 12px rgba(30, 41, 59, 0.06);
  --shadow-btn: 0 6px 20px rgba(255, 106, 61, 0.25);
  --shadow-btn-hover: 0 8px 28px rgba(255, 106, 61, 0.35);
  --shadow-inset: inset 0 2px 4px rgba(30, 41, 59, 0.04);

  /* 间距 */
  --gap-xs: 6px;
  --gap-sm: 10px;
  --gap-md: 16px;
  --gap-lg: 24px;
}

/* ========== 基础 ========== */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  font-size: 14.5px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;

  /* 柔和渐变背景 - 淡蓝到暖黄 */
  background:
    radial-gradient(ellipse 800px 600px at 15% 0%, rgba(59, 130, 246, 0.08) 0%, transparent 60%),
    radial-gradient(ellipse 700px 500px at 85% 10%, rgba(251, 191, 36, 0.08) 0%, transparent 55%),
    radial-gradient(ellipse 600px 500px at 50% 100%, rgba(255, 106, 61, 0.05) 0%, transparent 50%),
    linear-gradient(180deg, var(--bg-cool) 0%, var(--bg-warm) 60%, #fff 100%);
}

/* 装饰背景层 */
#bg-decor {
  position: fixed; inset: 0; pointer-events: none; z-index: 0;
  background:
    radial-gradient(circle at 20% 30%, rgba(59, 130, 246, 0.06), transparent 40%),
    radial-gradient(circle at 80% 70%, rgba(255, 106, 61, 0.05), transparent 40%);
}

.app { position: relative; z-index: 1; }

/* ========== 顶部导航 ========== */
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 20px 28px;
  max-width: 720px; margin: 0 auto;
}

.logo {
  display: flex; align-items: center; gap: 10px;
  text-decoration: none; color: var(--ink);
}

.logo-mark {
  width: 36px; height: 36px; border-radius: 12px;
  background: linear-gradient(135deg, var(--brand), var(--brand-light));
  color: #fff; display: inline-flex; align-items: center; justify-content: center;
  font-size: 18px; font-weight: 700;
  box-shadow: 0 4px 14px rgba(255, 106, 61, 0.3);
}

.logo-text { font-size: 18px; font-weight: 700; letter-spacing: 0.3px; }
.logo-accent { color: var(--brand); }

.nav { display: flex; gap: 6px; }
.nav-link {
  color: var(--ink-2); text-decoration: none; font-size: 13.5px;
  padding: 7px 14px; border-radius: var(--r-xs);
  transition: all 0.2s ease;
  font-weight: 500;
}
.nav-link:hover {
  color: var(--ink);
  background: rgba(255, 255, 255, 0.6);
  box-shadow: 0 2px 8px rgba(30, 41, 59, 0.06);
}
.nav-link.active {
  color: var(--brand);
  background: rgba(255, 106, 61, 0.08);
}

/* ========== 主内容区 ========== */
.main {
  max-width: 720px; margin: 0 auto;
  padding: 0 28px 60px;
}

.hero { padding: 8px 0 32px; }

.tagline {
  font-size: 28px; font-weight: 700; letter-spacing: 0.3px;
  margin: 0 0 8px; text-align: center;
  background: linear-gradient(135deg, var(--ink) 30%, var(--brand));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

.subline {
  color: var(--ink-2); margin: 0 0 28px;
  font-size: 14.5px; text-align: center;
}

/* ========== 卡片 ========== */
.card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: var(--r-xl);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  backdrop-filter: blur(24px) saturate(1.3);
  -webkit-backdrop-filter: blur(24px) saturate(1.3);
  transition: box-shadow 0.3s ease;
}
.card:hover { box-shadow: var(--shadow-card-hover); }

.card + .card { margin-top: 20px; }

.card-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 22px;
  background: linear-gradient(180deg, rgba(255,255,255,0.8) 0%, rgba(255,255,255,0.4) 100%);
  border-bottom: 1px solid rgba(30, 41, 59, 0.06);
}

.card-title {
  display: flex; align-items: center; gap: 10px;
  font-weight: 600; font-size: 15px; color: var(--ink);
}

.card-ico {
  width: 30px; height: 30px; border-radius: var(--r-xs);
  background: linear-gradient(135deg, rgba(255, 106, 61, 0.12), rgba(255, 140, 90, 0.08));
  color: var(--brand); display: inline-flex;
  align-items: center; justify-content: center; font-size: 14px;
}

/* 状态badge */
.card-badge {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 5px 12px; border-radius: 999px;
  background: var(--warn-bg); color: #92400e;
  font-size: 12.5px; font-weight: 500;
  border: 1px solid rgba(245, 158, 11, 0.15);
}
.card-badge .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--warn);
  box-shadow: 0 0 0 3px rgba(245, 158, 11, 0.2);
}
.card-badge.ok { background: var(--ok-bg); color: #166534; border-color: rgba(34, 197, 94, 0.15); }
.card-badge.ok .dot { background: var(--ok); box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.2); }
.card-badge.warn { background: var(--warn-bg); color: #92400e; }

/* ========== 连接卡片内容 ========== */
.stage { padding: 0 22px 24px; }
.stage > .card-header { margin: 0 -22px 0; }

.hint-text {
  color: var(--ink-2); text-align: center;
  margin: 20px 0 12px; font-size: 14px;
}

/* 房间号输入行 */
.room-row {
  display: flex; gap: 10px;
  margin: 6px 0 14px;
}

.room-input {
  flex: 1;
  padding: 14px 18px;
  border: 2px solid rgba(30, 41, 59, 0.08);
  border-radius: var(--r-md);
  font-size: 18px; letter-spacing: 4px; font-weight: 600;
  color: var(--ink); background: #fff;
  transition: all 0.25s ease;
  outline: none;
  text-align: center;
  box-shadow: var(--shadow-inset);
}
.room-input::placeholder {
  color: var(--ink-4); font-size: 14px; letter-spacing: 1px; font-weight: 400;
}
.room-input:focus {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-glow), var(--shadow-inset);
}

/* 按钮组 */
.btn-row { display: flex; gap: 10px; margin: 4px 0 14px; }

.btn-primary, .btn-ghost, .btn-outline {
  cursor: pointer; border: none; outline: none;
  padding: 13px 22px; border-radius: var(--r-md);
  font-size: 14.5px; font-weight: 600;
  transition: all 0.2s ease;
  display: inline-flex; align-items: center; justify-content: center;
  gap: 6px;
  white-space: nowrap;
}

.btn-primary {
  flex: 1;
  background: linear-gradient(135deg, var(--brand), var(--brand-light));
  color: #fff;
  box-shadow: var(--shadow-btn);
}
.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-btn-hover);
}
.btn-primary:active { transform: translateY(0); }
.btn-primary:disabled {
  opacity: 0.5; cursor: not-allowed;
  transform: none; box-shadow: none;
}

.btn-ghost {
  background: rgba(30, 41, 59, 0.05); color: var(--ink-2);
  border: 1px solid rgba(30, 41, 59, 0.08);
}
.btn-ghost:hover {
  background: rgba(30, 41, 59, 0.08); color: var(--ink);
  border-color: rgba(30, 41, 59, 0.12);
}
.btn-ghost:disabled { opacity: 0.4; cursor: not-allowed; }

.btn-outline {
  flex: 1;
  background: rgba(255, 255, 255, 0.6);
  color: var(--ink);
  border: 1.5px solid rgba(30, 41, 59, 0.1);
}
.btn-outline:hover {
  border-color: var(--brand); color: var(--brand);
  background: rgba(255, 106, 61, 0.04);
}

/* ========== 二维码区 ========== */
.qr-wrap {
  margin: 10px 0 8px; padding: 20px;
  border: 1.5px dashed rgba(30, 41, 59, 0.1);
  border-radius: var(--r-lg);
  background: linear-gradient(180deg, rgba(255,255,255,0.8), rgba(255,255,255,0.5));
  text-align: center;
}

.qr-box {
  width: 176px; height: 176px; margin: 0 auto;
  padding: 12px; background: #fff; border-radius: var(--r-md);
  display: inline-flex; align-items: center; justify-content: center;
  box-shadow: 0 4px 16px rgba(30, 41, 59, 0.08);
}
.qr-box img, .qr-box canvas {
  max-width: 100%; max-height: 100%; border-radius: 8px;
}

.qr-hint { color: var(--ink-2); margin: 12px 0 4px; font-size: 13.5px; }
.qr-url {
  color: #2563eb; font-size: 12.5px; margin: 0 0 14px;
  padding: 6px 12px; background: rgba(37, 99, 235, 0.06);
  border-radius: var(--r-xs); word-break: break-all;
  display: inline-block; max-width: 100%; font-weight: 500;
}

/* 连接提示 */
.conn-tip {
  margin-top: 6px; padding: 12px 16px; border-radius: var(--r-md);
  background: var(--ok-bg); color: #166534;
  display: flex; align-items: center; gap: 10px;
  font-size: 13.5px; font-weight: 500;
  border: 1px solid rgba(34, 197, 94, 0.12);
}
.conn-ic {
  width: 24px; height: 24px; border-radius: 50%;
  background: #fff; color: var(--ok);
  display: inline-flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 13px;
  box-shadow: 0 2px 6px rgba(34, 197, 94, 0.2);
}

/* ========== Tab切换 ========== */
.tabs {
  display: flex; gap: 4px;
  padding: 14px 18px 0;
  border-bottom: 1px solid rgba(30, 41, 59, 0.06);
  background: rgba(255, 255, 255, 0.4);
}

.tab {
  cursor: pointer; border: none; background: transparent;
  padding: 10px 18px; border-radius: var(--r-md) var(--r-md) 0 0;
  color: var(--ink-3); font-size: 14px; font-weight: 600;
  position: relative; transition: all 0.2s ease;
}
.tab:hover { color: var(--ink-2); }
.tab.active {
  color: var(--brand); background: rgba(255, 255, 255, 0.8);
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-bottom-color: #fff;
  margin-bottom: -1px;
}

.tab-panel { display: none; padding: 18px 18px 12px; }
.tab-panel.active { display: block; }

/* ========== 双栏布局 ========== */
.dual-col {
  display: grid; grid-template-columns: 1fr 1fr; gap: 14px;
}
@media (max-width: 720px) { .dual-col { grid-template-columns: 1fr; } }

.panel {
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-radius: var(--r-md);
  background: rgba(255, 255, 255, 0.5);
  padding: 14px;
  backdrop-filter: blur(10px);
}
.panel-title {
  font-weight: 700; margin: 0 0 10px; font-size: 14px;
  display: flex; align-items: center; gap: 6px;
}
.panel-row {
  display: flex; gap: 8px; margin-bottom: 10px;
  align-items: center; flex-wrap: wrap;
}
.panel-meta { font-size: 13px; color: var(--ink-3); }

/* 视频预览 */
.video-preview {
  width: 100%; aspect-ratio: 16/9;
  background: #0f172a;
  border-radius: var(--r-md);
  object-fit: contain; display: block;
}
.video-preview.big { min-height: 200px; }
.video-wrap { position: relative; border-radius: var(--r-md); overflow: hidden; }

.video-placeholder {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  color: var(--ink-3);
  background: linear-gradient(135deg, #1e293b, #0f172a);
  border-radius: var(--r-md);
  font-size: 14px; font-weight: 500;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

/* ========== 文件拖拽区 ========== */
.dropzone {
  border: 2px dashed rgba(30, 41, 59, 0.12);
  border-radius: var(--r-md);
  padding: 32px 20px; text-align: center;
  cursor: pointer; transition: all 0.25s ease;
  background: rgba(255, 255, 255, 0.4);
}
.dropzone:hover, .dropzone.dragover {
  border-color: var(--brand);
  background: rgba(255, 106, 61, 0.04);
}
.drop-icon {
  font-size: 32px; margin-bottom: 8px;
  opacity: 0.7;
}
.drop-title { font-weight: 700; color: var(--ink); margin-bottom: 4px; font-size: 15px; }
.drop-desc { color: var(--ink-3); font-size: 12.5px; }

/* ========== 文件列表 ========== */
.file-list {
  margin-top: 12px;
  display: flex; flex-direction: column; gap: 10px;
  max-height: 340px; overflow: auto;
}
.empty-tip {
  padding: 28px; text-align: center; color: var(--ink-3);
  background: rgba(255, 255, 255, 0.5);
  border-radius: var(--r-md);
  border: 1.5px dashed rgba(30, 41, 59, 0.08);
  font-size: 13.5px;
}

.file-item {
  display: grid;
  grid-template-columns: 40px 1fr auto;
  gap: 12px;
  padding: 12px 14px; border-radius: var(--r-md);
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(30, 41, 59, 0.06);
  align-items: center;
  backdrop-filter: blur(8px);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.file-item:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(30, 41, 59, 0.06);
}

.file-icon {
  width: 40px; height: 40px; border-radius: var(--r-sm);
  background: linear-gradient(135deg, rgba(255, 106, 61, 0.1), rgba(255, 140, 90, 0.06));
  color: var(--brand);
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 18px;
}
.file-name {
  font-weight: 600; font-size: 13.5px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
  max-width: 100%; color: var(--ink);
}
.file-meta { font-size: 12px; color: var(--ink-3); margin-top: 2px; }
.file-right { display: flex; align-items: center; gap: 8px; }
.file-percent {
  font-weight: 700; color: var(--ink); font-size: 13px;
  min-width: 46px; text-align: right;
}
.file-actions { display: flex; gap: 6px; }

.icon-btn {
  border: none; background: rgba(30, 41, 59, 0.05);
  color: var(--ink-2);
  width: 32px; height: 32px; border-radius: var(--r-xs);
  cursor: pointer; font-size: 14px;
  transition: all 0.2s ease;
  display: inline-flex; align-items: center; justify-content: center;
}
.icon-btn:hover {
  background: rgba(255, 106, 61, 0.1); color: var(--brand);
}

.progress {
  grid-column: 2 / span 2;
  margin-top: 8px;
  height: 5px;
  background: rgba(30, 41, 59, 0.06);
  border-radius: 999px; overflow: hidden;
}
.progress > span {
  display: block; height: 100%;
  background: linear-gradient(90deg, var(--brand), var(--brand-light));
  border-radius: 999px;
  transition: width 0.3s ease;
  width: 0%;
}

/* ========== 聊天 ========== */
.chat-box {
  height: 300px; overflow: auto; padding: 12px;
  background: rgba(255, 255, 255, 0.5);
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-radius: var(--r-md);
  display: flex; flex-direction: column; gap: 10px;
  margin-bottom: 10px;
}

.chat-msg {
  max-width: 78%;
  padding: 10px 14px; border-radius: var(--r-md);
  word-break: break-word; font-size: 13.5px; line-height: 1.5;
  animation: msgIn 0.2s ease;
}
@keyframes msgIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.chat-msg.me {
  align-self: flex-end;
  background: linear-gradient(135deg, var(--brand), var(--brand-light));
  color: #fff;
  border-bottom-right-radius: 3px;
  box-shadow: 0 4px 12px rgba(255, 106, 61, 0.2);
}
.chat-msg.other {
  align-self: flex-start;
  background: rgba(255, 255, 255, 0.85);
  color: var(--ink);
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-bottom-left-radius: 3px;
}
.chat-time { font-size: 11px; opacity: 0.65; margin-top: 4px; }

.chat-input-row { display: flex; gap: 8px; }
.chat-input {
  flex: 1; padding: 12px 16px; border-radius: var(--r-md);
  border: 1.5px solid rgba(30, 41, 59, 0.08); outline: none;
  font-size: 14px; background: #fff;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-inset);
}
.chat-input:focus {
  border-color: var(--brand);
  box-shadow: 0 0 0 4px var(--brand-glow), var(--shadow-inset);
}
.chat-input-row .btn-primary { flex: none; padding: 12px 20px; }
.chat-input-row .btn-ghost {
  width: 44px; height: 44px; padding: 0;
  display: inline-flex; align-items: center; justify-content: center;
  font-size: 20px; border-radius: var(--r-md);
}

/* ========== 文档区域 ========== */
.doc-section { padding: 50px 0 20px; }
.doc-section h2 {
  font-size: 24px; margin: 0 0 10px; color: var(--ink);
  font-weight: 700;
}
.doc-section.alt {
  background: linear-gradient(180deg, transparent, rgba(255,255,255,0.6) 50%);
  border-radius: var(--r-xl) var(--r-xl) 0 0;
  padding: 56px 28px 20px; margin: 0 -28px;
}
.doc-section.alt h2, .doc-section.alt .section-desc { padding: 0 28px; }
.section-desc { color: var(--ink-2); margin: 0 0 22px; font-size: 14.5px; }

.steps {
  list-style: none; padding: 0; margin: 0 0 28px;
  display: grid; gap: 12px;
}
.steps li {
  padding: 16px 18px;
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-radius: var(--r-md);
  box-shadow: 0 2px 8px rgba(30, 41, 59, 0.04);
  display: grid; grid-template-columns: 110px 1fr; gap: 14px; align-items: start;
  backdrop-filter: blur(8px);
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}
.steps li:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(30, 41, 59, 0.08);
}
.steps li b { font-weight: 700; color: var(--ink); }
.steps li span { color: var(--ink-2); font-size: 13.5px; }
@media (max-width: 640px) { .steps li { grid-template-columns: 1fr; } }

/* 特性网格 */
.feature-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px;
}
@media (max-width: 900px) { .feature-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .feature-grid { grid-template-columns: 1fr; } }

.feature {
  padding: 18px; border-radius: var(--r-md);
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(30, 41, 59, 0.06);
  box-shadow: 0 2px 8px rgba(30, 41, 59, 0.04);
  backdrop-filter: blur(8px);
  transition: transform 0.15s ease;
}
.feature:hover { transform: translateY(-2px); }
.ft-ic { font-size: 26px; }
.feature h3 { margin: 8px 0 4px; font-size: 15px; color: var(--ink); }
.feature p { margin: 0; color: var(--ink-2); font-size: 13px; }

/* 技术卡片 */
.tech-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px;
}
@media (max-width: 900px) { .tech-grid { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 520px) { .tech-grid { grid-template-columns: 1fr; } }

.tech-card {
  padding: 16px; border-radius: var(--r-md);
  background: linear-gradient(180deg, rgba(255,255,255,0.8), rgba(255,255,255,0.5));
  border: 1px solid rgba(30, 41, 59, 0.06);
  backdrop-filter: blur(8px);
  transition: transform 0.15s ease;
}
.tech-card:hover { transform: translateY(-2px); }
.tech-card h4 { margin: 0 0 6px; font-size: 14px; color: var(--ink); }
.tech-card p { margin: 0; font-size: 13px; color: var(--ink-2); }

/* 隐私框 */
.privacy-box {
  background: linear-gradient(180deg, rgba(255,255,255,0.8), rgba(255,247,240,0.6));
  border: 1px solid rgba(30, 41, 59, 0.06);
  border-radius: var(--r-xl);
  padding: 22px 24px;
  box-shadow: 0 2px 8px rgba(30, 41, 59, 0.04);
  backdrop-filter: blur(8px);
}
.privacy-box ul { margin: 10px 0 0; padding-left: 20px; color: var(--ink-2); }
.privacy-box li { margin: 6px 0; font-size: 13.5px; }

/* ========== 底部 ========== */
.footer {
  text-align: center; padding: 24px;
  color: var(--ink-3); font-size: 12.5px;
  border-top: 1px solid rgba(30, 41, 59, 0.06);
  margin-top: 30px;
  background: rgba(255, 255, 255, 0.4);
  backdrop-filter: blur(8px);
}
.footer-divider { opacity: 0.4; padding: 0 8px; }

/* ========== Toast提示 ========== */
.toast {
  position: fixed; left: 50%; bottom: 44px;
  transform: translateX(-50%);
  background: #1e293b; color: #fff;
  padding: 12px 20px; border-radius: var(--r-md);
  font-size: 13.5px; z-index: 100;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.2);
  animation: toastIn 0.25s ease;
  max-width: 90%; font-weight: 500;
  backdrop-filter: blur(8px);
}
.toast.ok { background: var(--ok); }
.toast.err { background: var(--err); }

@keyframes toastIn {
  from { opacity: 0; transform: translate(-50%, 10px); }
  to { opacity: 1; transform: translate(-50%, 0); }
}

.hidden { display: none !important; }

/* ========== 滚动条 ========== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: rgba(148, 163, 184, 0.35);
  border-radius: 999px;
}
::-webkit-scrollbar-thumb:hover { background: rgba(148, 163, 184, 0.6); }

/* ========== 移动端适配 ========== */
@media (max-width: 640px) {
  .topbar { padding: 14px 16px; }
  .nav { display: none; }
  .main { padding: 0 16px 40px; }
  .tagline { font-size: 22px; }
  .subline { font-size: 13px; }
  .card { border-radius: var(--r-lg); }
  .stage { padding: 0 16px 20px; }
  .stage > .card-header { margin: 0 -16px 0; padding: 14px 16px; }
  .room-input { font-size: 16px; padding: 12px 14px; }
  .qr-box { width: 150px; height: 150px; }
  .doc-section.alt { margin: 0 -16px; padding: 40px 16px 16px; }
  .doc-section.alt h2, .doc-section.alt .section-desc { padding: 0 16px; }
}