:root {
  --bg: #0d1117;
  --panel: #161b22;
  --line: #262d38;
  --ink: #e6edf3;
  --dim: #8b949e;
  --accent: #2f81f7;
  --bad: #f85149;
}
* { box-sizing: border-box; }
html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", Segoe UI, Helvetica, Arial, sans-serif;
}
.wrap {
  min-height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}
.card {
  width: 100%;
  max-width: 380px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 28px 24px;
}
h1 {
  margin: 0 0 6px;
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 0.5px;
}
p.sub {
  margin: 0 0 22px;
  color: var(--dim);
  font-size: 13px;
  line-height: 1.6;
}
input {
  width: 100%;
  padding: 13px 14px;
  font-size: 16px; /* 16px stops iOS Safari from zooming on focus */
  color: var(--ink);
  background: #0d1117;
  border: 1px solid var(--line);
  border-radius: 9px;
  outline: none;
}
input:focus { border-color: var(--accent); }
button {
  width: 100%;
  margin-top: 12px;
  padding: 13px;
  font-size: 15px;
  font-weight: 600;
  color: #fff;
  background: var(--accent);
  border: 0;
  border-radius: 9px;
  cursor: pointer;
}
button:disabled { opacity: 0.55; cursor: default; }
.err {
  margin-top: 12px;
  min-height: 18px;
  font-size: 13px;
  color: var(--bad);
}