:root {
  --bg: #0f1220;
  --bg-grad: radial-gradient(1200px 600px at 50% -10%, #1d2440 0%, #0f1220 60%);
  --card: #181c2e;
  --card-2: #1f2438;
  --accent: #6c8cff;
  --accent-2: #34d399;
  --text: #e7e9f3;
  --muted: #8b91ab;
  --danger: #f87171;
  --ring: #2a3050;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg-grad), var(--bg);
  display: flex;
  justify-content: center;
}

.app {
  width: 100%;
  max-width: 520px;
  padding: 32px 20px 40px;
}

.app-header { text-align: center; margin-bottom: 24px; }
.app-header h1 { margin: 0; font-size: 26px; letter-spacing: 1px; }
.subtitle { margin: 6px 0 0; color: var(--muted); font-size: 13px; }

/* 标签栏 */
.tabs {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 10px;
  margin-bottom: 18px;
  scrollbar-width: thin;
}
.tab {
  flex: 0 0 auto;
  padding: 8px 16px;
  border-radius: 999px;
  background: var(--card);
  border: 1px solid var(--ring);
  color: var(--muted);
  cursor: pointer;
  font-size: 14px;
  white-space: nowrap;
  transition: all 0.18s ease;
}
.tab:hover { color: var(--text); border-color: var(--accent); }
.tab.active {
  background: linear-gradient(135deg, var(--accent), #8aa2ff);
  color: #0d1020;
  border-color: transparent;
  font-weight: 600;
}

/* 卡片 */
.cards { position: relative; }
.card {
  background: linear-gradient(160deg, var(--card-2), var(--card));
  border: 1px solid var(--ring);
  border-radius: 20px;
  padding: 28px 24px;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.35);
  animation: fade 0.25s ease;
}
@keyframes fade { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }

.card-issuer { color: var(--accent); font-size: 13px; font-weight: 600; letter-spacing: 0.5px; }
.card-label { color: var(--muted); font-size: 14px; margin-top: 2px; }

.code-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 22px 0 18px;
  gap: 12px;
}
.code {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: 6px;
  font-variant-numeric: tabular-nums;
  cursor: pointer;
  user-select: all;
  transition: color 0.15s ease;
}
.code:hover { color: var(--accent-2); }
.code.copied { color: var(--accent-2); }

.copy-hint { font-size: 12px; color: var(--muted); min-width: 70px; text-align: right; }

/* 倒计时进度 */
.progress {
  height: 8px;
  border-radius: 999px;
  background: #11142400;
  border: 1px solid var(--ring);
  overflow: hidden;
}
.progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transition: width 0.9s linear;
  border-radius: 999px;
}
.progress-bar.low { background: linear-gradient(90deg, #fbbf24, var(--danger)); }

.countdown { text-align: right; font-size: 12px; color: var(--muted); margin-top: 8px; }

.app-footer { text-align: center; margin-top: 22px; font-size: 12px; color: var(--muted); }
.empty { text-align: center; color: var(--muted); padding: 40px 0; }