* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: 'MiSans', system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, 'Noto Sans SC', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: radial-gradient(1200px 600px at 20% 10%, #e6f0ff 0%, #f8f9ff 35%, #ffffff 70%),
              linear-gradient(135deg, #d8e9ff 0%, #f4e9ff 50%, #fff1e6 100%);
  color: #111827;
}
.app {
  min-height: 100%;
  display: grid;
  place-items: center;
  padding: 24px;
  position: relative;
}
.card {
  position: relative;
  width: min(680px, 100%);
  background: rgba(255,255,255,0.7);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(17, 24, 39, 0.06);
  box-shadow: 0 20px 40px rgba(31, 41, 55, 0.08);
  border-radius: 20px;
  padding: 36px 28px 56px;
  text-align: center;
}
.title {
  margin: 8px 0 6px;
  font-size: 28px;
  line-height: 1.2;
  font-weight: 800;
}
.subtitle {
  font-size: 14px;
  color: #6b7280;
  margin-bottom: 28px;
}
.actions {
  position: relative;
  height: 120px;
}
.btn {
  position: relative;
  appearance: none;
  border: none;
  cursor: pointer;
  padding: 12px 22px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  transition: transform 0.12s ease, box-shadow 0.12s ease, background-color 0.2s ease, color 0.2s ease;
}
.btn:active { transform: scale(0.98); }
.agree {
  background: #16a34a;
  color: #ffffff;
  box-shadow: 0 8px 20px rgba(22, 163, 74, 0.25);
}
.agree:hover { filter: brightness(1.05); }
.disagree {
  position: absolute;
  left: 52%;
  top: 52%;
  transform: translate(-50%, -50%);
  background: #f3f4f6;
  color: #111827;
  box-shadow: 0 8px 20px rgba(17, 24, 39, 0.1);
}
.disagree:hover { background: #e5e7eb; }
@media (max-width: 520px) {
  .card { padding: 28px 18px 50px; }
  .title { font-size: 22px; }
  .actions { height: 160px; }
}
.success-page {
  min-height: 100%;
  display: grid;
  place-items: center;
  background: linear-gradient(120deg, #fdf2f8, #eff6ff 40%, #ecfeff 80%);
}
.success-text {
  font-size: clamp(36px, 8vw, 72px);
  font-weight: 800;
  color: #111827;
  text-shadow: 0 10px 30px rgba(0,0,0,0.06);
}
/* mascot */
.mascot {
  position: fixed;
  bottom: 24px;
  left: 24px;
  width: clamp(120px, 16vw, 180px);
  height: auto;
  z-index: 20;
  pointer-events: none;
  opacity: 0.96;
}
.mascot-svg { width: 100%; height: auto; display: block; }
/* background pattern and watermark */
.app::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: radial-gradient(circle at 1px 1px, rgba(99, 102, 241, 0.12) 1px, transparent 1px),
    linear-gradient(90deg, rgba(79, 70, 229, 0.05) 1px, transparent 1px),
    linear-gradient(rgba(79, 70, 229, 0.05) 1px, transparent 1px);
  background-size: 18px 18px, 90px 1px, 1px 90px;
  background-position: 0 0, 0 0, 0 0;
  pointer-events: none;
  mask-image: radial-gradient(1200px 600px at 20% 10%, black 40%, transparent 70%);
}
.card::after {
  content: "CS CLUB • 计算机社团 • Open Source • AI • ACM • CTF";
  position: absolute;
  inset: 8px;
  display: block;
  color: rgba(17,24,39,0.04);
  font-weight: 800;
  font-size: 56px;
  letter-spacing: 2px;
  text-transform: uppercase;
  transform: rotate(-12deg);
  pointer-events: none;
  white-space: nowrap;
  overflow: hidden;
}
.footer {
  margin-top: 14px;
  font-size: 12px;
  color: #9ca3af;
}
.foot-link {
  color: #9ca3af;
  text-decoration: none;
  border-bottom: 1px dotted transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}
.foot-link:hover { color: #6b7280; border-color: #9ca3af; }
.dot { margin: 0 6px; color: #d1d5db; }
.success-page::after {
  content: "计算机社团";
  position: fixed;
  bottom: 12vh;
  right: 6vw;
  font-size: clamp(24px, 6vw, 48px);
  font-weight: 800;
  color: rgba(17,24,39,0.06);
  transform: rotate(-8deg);
  pointer-events: none;
}
.success-footer {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  background: rgba(255,255,255,0.6);
  backdrop-filter: blur(6px);
  border: 1px solid rgba(17,24,39,0.06);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 12px;
  color: #9ca3af;
}
.success-footer .tag { color: #9ca3af; }