:root {
  --bg: #eef2f7;
  --card: #ffffff;
  --ink: #1d2733;
  --muted: #5b6878;
  --accent: #1f6fd1;
  --accent-ink: #ffffff;
  --border: #cfd8e3;
  --error: #b42318;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12171e;
    --card: #1b222c;
    --ink: #e6ebf1;
    --muted: #9aa6b4;
    --accent: #5a9cf0;
    --accent-ink: #0b1220;
    --border: #2d3846;
    --error: #ff8a80;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.5 "Segoe UI", "Malgun Gothic", system-ui, sans-serif;
}
.card {
  width: min(380px, calc(100vw - 32px));
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 28px 28px 18px;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
}
h1 { margin: 0 0 6px; font-size: 22px; font-weight: 600; }
.brand { color: var(--accent); }
.lead { margin: 0 0 18px; color: var(--muted); }
label { display: block; font-weight: 600; margin-bottom: 6px; }
input {
  width: 100%;
  padding: 9px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: transparent;
  color: var(--ink);
  font: inherit;
}
input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }
button[type="submit"] {
  margin-top: 14px;
  width: 100%;
  padding: 9px;
  border: 0;
  border-radius: 6px;
  background: var(--accent);
  color: var(--accent-ink);
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}
#message { min-height: 1.5em; color: var(--error); margin: 10px 0 0; }
.lang { text-align: right; margin: 6px 0 0; }
.lang button { background: none; border: 0; color: var(--muted); cursor: pointer; font: inherit; }