:root {
  --primary: #2f9cdc;
  --primary-dark: #1f6ea8;
  --soft: #eff8ff;
  --text: #1f2937;
  --muted: #64748b;
  --border: #dbe7f7;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
  color: var(--text);
  background: radial-gradient(circle at 10% 0%, #f5fbff 0%, #f8fafc 50%, #f1f5f9 100%);
  display: flex;
  flex-direction: column;
}
.wrap {
  width: min(760px, calc(100% - 32px));
  margin: 72px auto 28px;
  background: rgba(255,255,255,.96);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: 0 18px 40px rgba(15,23,42,.12);
  padding: 34px 28px;
  text-align: center;
  position: relative;
  overflow: hidden;
  isolation: isolate;
}
.wrap::before {
  content: "";
  position: absolute;
  inset: -30% -20% auto auto;
  width: 420px;
  height: 420px;
  background:
    radial-gradient(circle at 24% 30%, rgba(47,156,220,.18) 0 26%, transparent 27% 100%),
    radial-gradient(circle at 72% 68%, rgba(47,156,220,.12) 0 20%, transparent 21% 100%),
    linear-gradient(120deg, rgba(47,156,220,.12), rgba(47,156,220,.02));
  border-radius: 32px;
  transform: rotate(-14deg);
  opacity: .55;
  pointer-events: none;
  z-index: 0;
}
.wrap::after {
  content: "";
  position: absolute;
  right: 70px;
  top: 96px;
  width: 220px;
  height: 130px;
  border: 1px dashed rgba(47,156,220,.28);
  border-radius: 16px;
  opacity: .45;
  transform: rotate(-8deg);
  pointer-events: none;
  z-index: 0;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
  color: #0f172a;
  font-weight: 700;
  font-size: 14px;
  letter-spacing: .2px;
  position: relative;
  z-index: 1;
}
.brand img {
  height: 22px;
  width: auto;
  display: block;
}
.badge {
  width: 30px;
  height: 30px;
  margin: 0 auto 8px;
  border-radius: 999px;
  background: linear-gradient(180deg, #5cc0f2, #2f9cdc);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  box-shadow: 0 10px 22px rgba(47,156,220,.35);
  position: relative;
  z-index: 1;
}
.code {
  margin: 0;
  font-size: clamp(52px, 9vw, 92px);
  line-height: 1;
  letter-spacing: 2px;
  color: var(--primary);
  text-shadow: 0 8px 20px rgba(47,156,220,.28);
  animation: pulse404 2.2s ease-in-out infinite;
  position: relative;
  z-index: 1;
}
h1 {
  margin: 12px 0 10px;
  font-size: clamp(24px, 4vw, 34px);
  position: relative;
  z-index: 1;
}
.desc {
  margin: 0 auto 20px;
  max-width: 520px;
  color: var(--muted);
  line-height: 1.75;
  font-size: 15px;
  position: relative;
  z-index: 1;
}
.actions {
  display: flex;
  justify-content: center;
  gap: 10px;
  flex-wrap: wrap;
  margin-bottom: 16px;
  position: relative;
  z-index: 1;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 132px;
  min-height: 40px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
  transition: all .18s ease;
}
.btn-primary {
  color: #fff;
  border-color: var(--primary);
  background: linear-gradient(180deg, #42ace4, var(--primary));
  box-shadow: 0 8px 18px rgba(47,156,220,.3);
}
.btn-ghost {
  color: var(--primary-dark);
  background: var(--soft);
}
.btn:hover { transform: translateY(-1px); }
.hint { font-size: 13px; color: #94a3b8; position: relative; z-index: 1; }
.smart-guess {
  margin: 14px auto 0;
  max-width: 620px;
  text-align: left;
  border: 1px solid #dbe7f7;
  border-radius: 12px;
  background: rgba(255,255,255,.88);
  padding: 12px;
  position: relative;
  z-index: 1;
}
.smart-guess h3 {
  margin: 0 0 8px;
  font-size: 15px;
}
.smart-guess p {
  margin: 0 0 8px;
  color: #64748b;
  font-size: 13px;
  line-height: 1.7;
}
.smart-guess ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 6px;
}
.smart-guess a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  text-decoration: none;
  color: #1f6ea8;
  font-size: 14px;
}
.smart-guess a::before {
  content: "→";
  color: #2f9cdc;
}
.smart-guess code {
  font-family: Consolas, "Courier New", monospace;
  background: #f1f5f9;
  border-radius: 6px;
  padding: 1px 6px;
}
@keyframes pulse404 {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-2px); }
}
@media (max-width: 640px) {
  .wrap { margin-top: 48px; padding: 26px 16px; border-radius: 14px; }
  .actions { flex-direction: column; align-items: stretch; }
  .btn { width: 100%; }
}