:root {
  color-scheme: light dark;
  --canvas-a: #eef2ff;
  --canvas-b: #dbeafe;
  --canvas-c: #f5d0fe;
  --glass: rgba(255, 255, 255, 0.66);
  --glass-border: rgba(255, 255, 255, 0.78);
  --text: #172033;
  --muted: #667085;
  --input: rgba(255, 255, 255, 0.72);
  --input-border: rgba(126, 145, 175, 0.28);
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-ring: rgba(37, 99, 235, 0.18);
  --danger: #b42318;
  --danger-soft: rgba(254, 226, 226, 0.76);
  --shadow: 0 24px 70px rgba(45, 55, 85, 0.18);
}

* { box-sizing: border-box; }
html, body { min-height: 100%; }

body {
  margin: 0;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 18% 18%, rgba(129, 140, 248, 0.42), transparent 34%),
    radial-gradient(circle at 82% 22%, rgba(236, 72, 153, 0.25), transparent 32%),
    radial-gradient(circle at 68% 82%, rgba(56, 189, 248, 0.28), transparent 34%),
    linear-gradient(135deg, var(--canvas-a), var(--canvas-b) 48%, var(--canvas-c));
  background-attachment: fixed;
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans KR", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.5;
}

body::before,
body::after {
  position: fixed;
  z-index: -1;
  width: 280px;
  height: 280px;
  border-radius: 999px;
  content: "";
  filter: blur(12px);
  opacity: 0.55;
}

body::before {
  top: -90px;
  left: -70px;
  background: rgba(99, 102, 241, 0.34);
}

body::after {
  right: -80px;
  bottom: -100px;
  background: rgba(14, 165, 233, 0.30);
}

.shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 32px 20px;
}

.card {
  width: min(100%, 420px);
  padding: 40px;
  border: 1px solid var(--glass-border);
  border-radius: 28px;
  background: var(--glass);
  box-shadow: var(--shadow);
  backdrop-filter: blur(20px) saturate(145%);
  -webkit-backdrop-filter: blur(20px) saturate(145%);
}

.brand {
  width: 52px;
  height: 52px;
  display: grid;
  place-items: center;
  margin-bottom: 24px;
  border: 1px solid rgba(255, 255, 255, 0.68);
  border-radius: 16px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  box-shadow: 0 12px 28px rgba(37, 99, 235, 0.28);
  color: #fff;
  font-size: 22px;
  font-weight: 800;
  letter-spacing: -0.03em;
}

.heading { margin-bottom: 28px; }

.eyebrow {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.12em;
}

h1 {
  margin: 0;
  font-size: 30px;
  line-height: 1.25;
  letter-spacing: -0.035em;
}

.description {
  margin: 12px 0 0;
  color: var(--muted);
}

.alerts { margin: 0 0 20px; }

.alert {
  padding: 12px 14px;
  border: 1px solid rgba(248, 113, 113, 0.38);
  border-radius: 12px;
  background: var(--danger-soft);
  color: var(--danger);
  font-size: 14px;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.alert-success {
  border-color: rgba(34, 197, 94, 0.38);
  background: rgba(220, 252, 231, 0.76);
  color: #15803d;
}

form { display: grid; gap: 10px; }

label {
  margin-top: 4px;
  font-size: 14px;
  font-weight: 700;
}

input {
  width: 100%;
  min-height: 50px;
  padding: 10px 13px;
  border: 1px solid var(--input-border);
  border-radius: 14px;
  outline: none;
  background: var(--input);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.64);
  color: var(--text);
  font: inherit;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: border-color 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

input:focus {
  border-color: var(--accent);
  background: rgba(255, 255, 255, 0.86);
  box-shadow: 0 0 0 4px var(--accent-ring);
}

button {
  min-height: 50px;
  margin-top: 12px;
  border: 0;
  border-radius: 14px;
  background: linear-gradient(135deg, #2563eb, #4f46e5);
  box-shadow: 0 14px 28px rgba(37, 99, 235, 0.26);
  color: #fff;
  cursor: pointer;
  font: inherit;
  font-weight: 800;
  transition: transform 0.18s ease, box-shadow 0.18s ease, filter 0.18s ease;
}

button:hover {
  transform: translateY(-1px);
  box-shadow: 0 18px 34px rgba(37, 99, 235, 0.32);
  filter: brightness(1.04);
}

button:active { transform: translateY(1px); }

button:focus-visible {
  outline: 4px solid var(--accent-ring);
  outline-offset: 3px;
}

.button-row { display: grid; gap: 10px; }
.danger-button {
  background: linear-gradient(135deg, #dc2626, #b91c1c);
  box-shadow: 0 14px 28px rgba(185, 28, 28, 0.24);
}
.danger-button:hover {
  box-shadow: 0 18px 34px rgba(185, 28, 28, 0.30);
}

.field-help {
  margin: -4px 0 4px;
  color: var(--muted);
  font-size: 13px;
}

.secondary-link {
  display: block;
  margin-top: 18px;
  color: var(--accent);
  font-size: 14px;
  font-weight: 700;
  text-align: center;
  text-decoration: none;
}

.secondary-link:hover { text-decoration: underline; }

.notice {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.notice span {
  margin-top: 5px;
  color: #16a34a;
  font-size: 10px;
}

@media (max-width: 520px) {
  .shell { padding: 20px 16px; }
  .card { padding: 30px 24px; border-radius: 24px; }
  h1 { font-size: 27px; }
}

@media (prefers-color-scheme: dark) {
  :root {
    --canvas-a: #0f172a;
    --canvas-b: #172554;
    --canvas-c: #2e1065;
    --glass: rgba(15, 23, 42, 0.64);
    --glass-border: rgba(255, 255, 255, 0.18);
    --text: #f8fafc;
    --muted: rgba(241, 245, 249, 0.68);
    --input: rgba(15, 23, 42, 0.54);
    --input-border: rgba(255, 255, 255, 0.18);
    --accent: #93c5fd;
    --accent-hover: #bfdbfe;
    --accent-ring: rgba(147, 197, 253, 0.18);
    --danger: #fca5a5;
    --danger-soft: rgba(127, 29, 29, 0.30);
    --shadow: 0 28px 80px rgba(0, 0, 0, 0.38);
  }

  input:focus { background: rgba(15, 23, 42, 0.76); }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    transition: none !important;
  }
}