body { min-height: 100vh; display: grid; place-items: center; padding: 24px 16px; overflow: hidden; }

/* ---------- 开机动画：紫色图标像苹果打开 App 一样放大到全屏 ---------- */
.boot {
  position: fixed;
  inset: 0;
  z-index: 50;
  background: #000;
  display: grid;
  place-items: center;
  cursor: pointer;
}
.boot-tile {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--accent);
  clip-path: inset(calc(50% - 46px) calc(50% - 46px) round 22px);
  opacity: 0;
  transform: scale(0.82);
  animation:
    tile-in 0.55s cubic-bezier(0.16, 1, 0.3, 1) 0.25s forwards,
    tile-open 0.9s cubic-bezier(0.76, 0, 0.24, 1) 1.15s forwards;
}
.boot-tile img { width: 56px; height: 56px; animation: mark-out 0.5s ease 1.15s forwards; }
@keyframes tile-in { to { opacity: 1; transform: scale(1); } }
@keyframes tile-open {
  0% { clip-path: inset(calc(50% - 46px) calc(50% - 46px) round 22px); background: var(--accent); }
  70% { background: var(--accent); }
  100% { clip-path: inset(0 0 round 0); background: var(--bg); }
}
@keyframes mark-out { to { opacity: 0; transform: scale(2.4); } }
.boot.done { animation: boot-out 0.35s ease forwards; }
@keyframes boot-out { to { opacity: 0; visibility: hidden; } }

/* ---------- 登录 ---------- */
.login { width: 100%; max-width: 340px; text-align: center; }
.mark { width: 64px; height: 64px; }
h1 { font-size: 44px; font-weight: 800; letter-spacing: 0.08em; line-height: 1.1; margin: 22px 0 10px; }
.sub { color: var(--text-2); margin: 0 0 32px; font-size: 13px; }

/* 动画结束后依次出现：图标 → 标题 → 说明 → 输入框 */
.booting .login > * { opacity: 0; transform: translateY(14px); }
.revealed .login > * { animation: rise 0.7s cubic-bezier(0.16, 1, 0.3, 1) forwards; }
.revealed .login > :nth-child(2) { animation-delay: 0.08s; letter-spacing: 0.3em; animation-name: rise-title; }
.revealed .login > :nth-child(3) { animation-delay: 0.18s; }
.revealed .login > :nth-child(4) { animation-delay: 0.28s; }
@keyframes rise { to { opacity: 1; transform: none; } }
@keyframes rise-title { to { opacity: 1; transform: none; letter-spacing: 0.08em; } }

form { display: grid; gap: 10px; }
input {
  height: 46px;
  padding: 0 14px;
  border-radius: 10px;
  border: 1px solid var(--line-strong);
  background: var(--bg-raise);
  color: var(--text);
  font: inherit;
  text-align: center;
  transition: border-color 0.15s, box-shadow 0.15s;
}
input::placeholder { color: var(--text-3); }
input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
form .btn { height: 46px; font-size: 15px; border-radius: 10px; }
.error { min-height: 20px; margin: 4px 0 0; color: var(--red); font-size: 13px; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

@media (prefers-reduced-motion: reduce) {
  .boot { display: none; }
  .booting .login > * { opacity: 1; transform: none; }
}