:root {
  color-scheme: dark;
  --bg: #06121b;
  --surface: #0a1a25;
  --surface-2: #102532;
  --line: rgba(148, 170, 188, .22);
  --text: #eef5f8;
  --muted: #91a6b4;
  --teal: #45e0c1;
  --red: #ff6b72;
  --green: #63e6a5;
  font-family: Inter, Pretendard, "Noto Sans KR", system-ui, sans-serif;
}
* { box-sizing: border-box; }
body {
  min-height: 100vh;
  margin: 0;
  display: grid;
  place-items: center;
  color: var(--text);
  background:
    radial-gradient(circle at 18% 18%, rgba(69, 224, 193, .10), transparent 34%),
    radial-gradient(circle at 82% 75%, rgba(91, 167, 255, .08), transparent 32%),
    var(--bg);
}
button, input { font: inherit; }
button { cursor: pointer; }
.auth-shell {
  width: min(980px, calc(100% - 32px));
  display: grid;
  grid-template-columns: .9fr 1.1fr;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: rgba(7, 20, 29, .92);
  box-shadow: 0 28px 90px rgba(0, 0, 0, .38);
}
.auth-intro {
  min-height: 590px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 54px;
  border-right: 1px solid var(--line);
  background: linear-gradient(145deg, rgba(69, 224, 193, .08), rgba(8, 22, 31, .6));
}
.brand-mark {
  width: 54px;
  height: 54px;
  display: grid;
  place-items: center;
  margin-bottom: 32px;
  border-radius: 14px;
  color: #042019;
  background: var(--teal);
  font-size: 19px;
  font-weight: 900;
  letter-spacing: -.05em;
}
.kicker, .eyebrow {
  color: var(--teal);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: .16em;
}
h1 { margin: 9px 0 7px; font-size: 48px; letter-spacing: -.055em; }
h2 { margin: 7px 0 28px; font-size: 30px; letter-spacing: -.035em; }
p { margin: 0; color: var(--muted); }
.auth-card { min-height: 590px; padding: 42px 52px; }
.mode-tabs {
  display: inline-flex;
  gap: 4px;
  margin-bottom: 38px;
  padding: 4px;
  border: 1px solid var(--line);
  border-radius: 11px;
  background: var(--bg);
}
.mode-tabs button {
  padding: 9px 17px;
  border: 0;
  border-radius: 8px;
  color: var(--muted);
  background: transparent;
}
.mode-tabs button.active { color: var(--teal); background: var(--surface-2); }
.auth-panel { display: none; }
.auth-panel.active { display: block; }
form { display: grid; gap: 17px; }
label { display: grid; gap: 8px; color: #c8d5dc; font-size: 13px; font-weight: 650; }
input {
  width: 100%;
  min-height: 48px;
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  outline: none;
  color: var(--text);
  background: rgba(4, 15, 23, .75);
}
input:focus { border-color: rgba(69, 224, 193, .68); box-shadow: 0 0 0 3px rgba(69, 224, 193, .08); }
form small { margin-top: -10px; color: var(--muted); font-size: 12px; }
form button {
  min-height: 48px;
  margin-top: 7px;
  border: 1px solid rgba(69, 224, 193, .55);
  border-radius: 10px;
  color: #042019;
  background: var(--teal);
  font-weight: 800;
}
form button:disabled { cursor: wait; opacity: .55; }
.auth-message {
  min-height: 22px;
  margin-top: 20px;
  color: var(--red);
  font-size: 13px;
  line-height: 1.6;
}
.auth-message.success { color: var(--green); }
@media (max-width: 760px) {
  body { place-items: start center; padding: 18px 0; }
  .auth-shell { grid-template-columns: 1fr; }
  .auth-intro { min-height: auto; padding: 30px; border-right: 0; border-bottom: 1px solid var(--line); }
  .brand-mark { margin-bottom: 22px; }
  h1 { font-size: 38px; }
  .auth-card { min-height: 520px; padding: 30px; }
}