: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% - 24px));
  margin: 42px auto 20px;
  background: rgba(255,255,255,.96);
  border: 1px solid var(--border);
  border-radius: 16px;
  box-shadow: 0 16px 34px rgba(15,23,42,.12);
  padding: 24px 14px;
  text-align: center;
  position: relative;
  overflow: hidden;
  isolation: isolate;
}
.wrap::before {
  content: "";
  position: absolute;
  right: -130px;
  top: -110px;
  width: 280px;
  height: 280px;
  border-radius: 28px;
  background:
    radial-gradient(circle at 24% 30%, rgba(47,156,220,.16) 0 24%, transparent 25% 100%),
    radial-gradient(circle at 72% 68%, rgba(47,156,220,.12) 0 18%, transparent 19% 100%),
    linear-gradient(120deg, rgba(47,156,220,.12), rgba(47,156,220,.02));
  transform: rotate(-14deg);
  opacity: .6;
  z-index: 0;
  pointer-events: none;
}
.wrap::after {
  content: "";
  position: absolute;
  right: 28px;
  top: 76px;
  width: 140px;
  height: 88px;
  border: 1px dashed rgba(47,156,220,.3);
  border-radius: 12px;
  opacity: .45;
  transform: rotate(-8deg);
  z-index: 0;
  pointer-events: none;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 8px;
  color: #0f172a;
  font-weight: 700;
  font-size: 13px;
  position: relative;
  z-index: 1;
}
.brand img {
  height: 20px;
  width: auto;
  display: block;
}
.badge {
  width: 28px;
  height: 28px;
  margin: 0 auto 6px;
  border-radius: 999px;
  background: linear-gradient(180deg, #5cc0f2, #2f9cdc);
  color: #fff;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  box-shadow: 0 8px 20px rgba(47,156,220,.35);
  position: relative;
  z-index: 1;
}
.code {
  margin: 0;
  font-size: clamp(48px, 16vw, 84px);
  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: 10px 0 8px;
  font-size: clamp(22px, 6.6vw, 30px);
  line-height: 1.3;
  position: relative;
  z-index: 1;
}
.desc {
  margin: 0 auto 16px;
  max-width: 520px;
  color: var(--muted);
  line-height: 1.72;
  font-size: 14px;
  text-align: left;
  position: relative;
  z-index: 1;
}
.actions {
  display: grid;
  grid-template-columns: 1fr;
  gap: 8px;
  margin-bottom: 12px;
  position: relative;
  z-index: 1;
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid var(--border);
  text-decoration: none;
  font-size: 14px;
  font-weight: 600;
}
.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);
}
.hint { font-size: 12px; color: #94a3b8; position: relative; z-index: 1; }
.smart-guess {
  margin: 12px auto 0;
  text-align: left;
  border: 1px solid #dbe7f7;
  border-radius: 10px;
  background: rgba(255,255,255,.9);
  padding: 10px;
  position: relative;
  z-index: 1;
}
.smart-guess h3 {
  margin: 0 0 6px;
  font-size: 14px;
}
.smart-guess p {
  margin: 0 0 7px;
  color: #64748b;
  font-size: 12px;
  line-height: 1.65;
}
.smart-guess ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 5px;
}
.smart-guess a {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  text-decoration: none;
  color: #1f6ea8;
  font-size: 13px;
}
.smart-guess a::before {
  content: "→";
  color: #2f9cdc;
}
.smart-guess code {
  font-family: Consolas, "Courier New", monospace;
  background: #f1f5f9;
  border-radius: 5px;
  padding: 1px 5px;
}
@keyframes pulse404 {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-2px); }
}