:root { color-scheme: dark; }
* { box-sizing: border-box; }
html, body { min-height: 100%; margin: 0; }
body.signin-body {
  min-height: 100vh;
  overflow: hidden;
  color: #f0f1f3;
  background:
    radial-gradient(circle at 18% 12%, rgba(120, 124, 132, .16), transparent 34%),
    radial-gradient(circle at 86% 88%, rgba(40, 42, 46, .45), transparent 32%),
    #090a0c;
  font: 16px/1.5 Inter, ui-sans-serif, system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
}
.signin-atmosphere { position: fixed; inset: 0; pointer-events: none; }
.signin-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(80px);
  opacity: .55;
  animation: signinDrift 18s ease-in-out infinite alternate;
}
.signin-orb-a { width: 46vw; height: 46vw; top: -20%; left: -14%; background: #3a3d44; }
.signin-orb-b { width: 36vw; height: 36vw; right: -12%; bottom: -18%; background: #1a1c20; animation-delay: -7s; }
.signin-orb-c { width: 20vw; height: 20vw; top: 42%; left: 58%; background: #5a5e66; opacity: .28; animation-delay: -3s; }
.signin-grid {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(200, 204, 212, .1) 1px, transparent 1px);
  background-size: 24px 24px;
  mask-image: radial-gradient(circle at 50% 42%, #000 18%, transparent 74%);
  opacity: .45;
}
@keyframes signinDrift {
  from { transform: translate3d(0, 0, 0) scale(1); }
  to { transform: translate3d(3%, -4%, 0) scale(1.06); }
}
.signin-stage {
  position: relative;
  z-index: 1;
  display: grid;
  min-height: 100vh;
  place-content: center;
  justify-items: center;
  padding: 36px 20px 48px;
  text-align: center;
  animation: signinRise .7s cubic-bezier(.22, .8, .18, 1) both;
}
@keyframes signinRise {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: none; }
}
.signin-mark {
  display: grid;
  justify-items: center;
  gap: 12px;
  margin-bottom: 26px;
  color: #f0f1f3;
  letter-spacing: .32em;
  font-size: 12px;
  font-weight: 800;
  text-decoration: none;
}
.signin-mark img {
  width: 78px;
  height: 78px;
  object-fit: contain;
  filter: drop-shadow(0 16px 36px rgba(0, 0, 0, .55));
}
.signin-mark span {
  padding-bottom: 6px;
  border-bottom: 1px solid rgba(255, 255, 255, .22);
}
.signin-stage h1 {
  margin: 0;
  font-size: clamp(40px, 7vw, 64px);
  letter-spacing: -.055em;
  line-height: .98;
  font-weight: 800;
  color: #f5f6f7;
}
.signin-lead {
  max-width: 34ch;
  margin: 16px 0 28px;
  color: #a8adb6;
  font-size: 15px;
  line-height: 1.55;
}
.signin-form {
  display: grid;
  gap: 18px;
  width: min(100%, 420px);
  padding: 22px 22px 20px;
  border: 1px solid rgba(180, 184, 192, .14);
  border-radius: 22px;
  background: rgba(17, 18, 20, .72);
  box-shadow: 0 24px 80px rgba(0, 0, 0, .45);
  backdrop-filter: blur(18px);
}
.signin-agree {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  color: #c8ccd3;
  font-size: 13px;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
}
.signin-agree input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}
.signin-agree i {
  flex: 0 0 auto;
  width: 20px;
  height: 20px;
  margin-top: 1px;
  border: 1.5px solid rgba(180, 184, 192, .4);
  border-radius: 6px;
  background: rgba(255, 255, 255, .04);
  transition: border-color .16s ease, background .16s ease, box-shadow .16s ease;
}
.signin-agree i::after {
  display: block;
  width: 5px;
  height: 9px;
  margin: 2px 0 0 6px;
  border: solid #f0f1f3;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg) scale(0);
  content: '';
  transition: transform .16s ease;
}
.signin-agree:hover i { border-color: #9aa0a8; }
.signin-agree input:focus-visible + i {
  box-shadow: 0 0 0 3px rgba(180, 184, 192, .22);
}
.signin-agree input:checked + i {
  border-color: #8b9098;
  background: #2a2c31;
}
.signin-agree input:checked + i::after { transform: rotate(45deg) scale(1); }
.signin-agree a {
  color: #f0f1f3;
  font-weight: 700;
  text-decoration: underline;
  text-underline-offset: 3px;
}
.signin-form button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 52px;
  border: 1px solid rgba(200, 204, 212, .18);
  border-radius: 14px;
  color: #f5f6f7;
  background: linear-gradient(180deg, #3a3d44, #1c1e22);
  box-shadow: 0 12px 28px rgba(0, 0, 0, .4);
  font: inherit;
  font-size: 15px;
  font-weight: 800;
  cursor: pointer;
  transition: transform .18s ease, filter .18s ease, box-shadow .18s ease, background .18s ease, color .18s ease, border-color .18s ease;
}
.signin-form button svg { width: 22px; height: 22px; }
.signin-form button:hover:not(:disabled) {
  transform: translateY(-1px);
  filter: brightness(1.08);
  border-color: rgba(220, 224, 230, .28);
  box-shadow: 0 16px 34px rgba(0, 0, 0, .5);
}
.signin-form button:disabled {
  color: rgba(240, 241, 243, .38);
  background: rgba(255, 255, 255, .06);
  border-color: rgba(255, 255, 255, .06);
  box-shadow: none;
  cursor: not-allowed;
  filter: none;
}
.signin-note {
  max-width: 42ch;
  margin: 20px 0 0;
  color: #7e848e;
  font-size: 12px;
  line-height: 1.5;
}
@media (prefers-reduced-motion: reduce) {
  .signin-orb, .signin-stage { animation: none; }
}