:root {
  color-scheme: light;
  --bg: #f3f5f9;
  --panel: #ffffff;
  --border: #dfe4ea;
  --text: #1c212c;
  --muted: #68717f;
  --accent: #2456c4;
  --accent-soft: #e8eefc;
  --bad: #bd3131;
  --bad-soft: #fbe7e7;
  --input-bg: #f2f4f8;
  --input-border: #cdd4de;
  --shadow-lift: 0 4px 14px rgba(24, 34, 56, 0.12);
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #12151c;
    --panel: #1b1f28;
    --border: #2c323e;
    --text: #e4e8ef;
    --muted: #9aa2b1;
    --accent: #3987e5;
    --accent-soft: #1d2b45;
    --bad: #e06c6c;
    --bad-soft: #3a1c1c;
    --input-bg: #13161d;
    --input-border: #3a4150;
    --shadow-lift: 0 4px 16px rgba(0, 0, 0, 0.5);
  }
}

* { box-sizing: border-box; }
html { font-size: clamp(14px, 12px + 0.22vw, 17.5px); -webkit-text-size-adjust: 100%; }
html, body { min-height: 100%; margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 1rem/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}
.login-shell { min-height: 100dvh; display: grid; place-items: center; padding: 1.25rem; }
.login-card {
  width: min(24rem, 100%);
  padding: 1.7rem;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow-lift);
}
.brand { display: flex; align-items: center; gap: 0.6rem; color: var(--text); font-size: 1.12rem; font-weight: 750; letter-spacing: 0.01em; }
.brand img { display: block; width: 2rem; height: 2rem; object-fit: contain; }
h1 { margin: 1.2rem 0 0.85rem; font-size: 1.35rem; line-height: 1.3; }
form { display: grid; gap: 0.45rem; }
label { margin-top: 0.55rem; font-size: 0.905rem; font-weight: 600; }
input {
  width: 100%;
  border: 1px solid var(--input-border);
  border-radius: 8px;
  padding: 0.58rem 0.7rem;
  background: var(--input-bg);
  color: var(--text);
  font: inherit;
}
input:focus { outline: none; border-color: var(--accent); background: var(--panel); box-shadow: 0 0 0 3px var(--accent-soft); }
button {
  appearance: none;
  width: 100%;
  min-height: 2.65rem;
  margin-top: 1rem;
  border: 1px solid var(--accent);
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}
button:hover { filter: brightness(0.92); }
button:focus { outline: none; }
button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.error { margin: 0 0 0.7rem; border-radius: 9px; padding: 0.55rem 0.7rem; background: var(--bad-soft); color: var(--bad); font-size: 0.9rem; }

@media (max-width: 480px) {
  .login-shell { align-items: start; padding: 8vh 1rem 1rem; }
  .login-card { padding: 1.25rem; }
}