:root {
  --vermillion: #c8412d;
  --vermillion-dark: #a8341f;
  --ink: #1a1a1a;
  --ink-2: #4a4a4a;
  --ink-3: #8a8a8a;
  --line: #ececec;
  --bg: #f6f4ef;
  --card: #ffffff;
  --radius: 12px;
  --shadow: 0 8px 32px rgba(30, 20, 10, .08);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1200px 600px at 80% -10%, rgba(200,65,45,.08), transparent 60%),
    radial-gradient(800px 400px at -10% 110%, rgba(200,65,45,.06), transparent 60%),
    var(--bg);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.auth-wrap { width: 100%; max-width: 420px; }

.auth-card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 32px 28px 24px;
  border: 1px solid var(--line);
}

.brand { text-align: center; margin-bottom: 24px; }
.brand-seal {
  display: inline-flex;
  align-items: center; justify-content: center;
  width: 48px; height: 48px;
  background: var(--vermillion);
  color: #fff;
  font-family: "STKaiti", "KaiTi", "FangSong", serif;
  font-size: 28px; font-weight: 700;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(200,65,45,.3);
  letter-spacing: 0;
}
.brand-title {
  margin: 12px 0 4px;
  font-size: 22px; font-weight: 700;
  letter-spacing: .5px;
}
.brand-sub { margin: 0; font-size: 13px; color: var(--ink-3); }

.tabs {
  display: flex;
  background: #f4f2ee;
  border-radius: 10px;
  padding: 4px;
  margin-bottom: 20px;
}
.tab {
  flex: 1;
  border: 0;
  background: transparent;
  padding: 10px 0;
  font-size: 14px;
  color: var(--ink-2);
  border-radius: 8px;
  cursor: pointer;
  font-weight: 500;
  transition: all .2s;
}
.tab.active {
  background: #fff;
  color: var(--vermillion);
  box-shadow: 0 1px 3px rgba(0,0,0,.06);
}

.form { display: none; flex-direction: column; gap: 14px; }
.form.active { display: flex; }

.field { display: flex; flex-direction: column; gap: 6px; }
.field-label { font-size: 13px; color: var(--ink-2); }
.field input[type="email"],
.field input[type="password"] {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 11px 12px;
  font-size: 14px;
  background: #fafafa;
  transition: border-color .15s, background .15s;
  outline: none;
  width: 100%;
  font-family: inherit;
}
.field input:focus {
  border-color: var(--vermillion);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(200,65,45,.1);
}

.row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  color: var(--ink-2);
}
.remember { display: inline-flex; align-items: center; gap: 6px; cursor: pointer; }
.link { color: var(--vermillion); text-decoration: none; }
.link:hover { text-decoration: underline; }

.agree { font-size: 12px; color: var(--ink-2); display: flex; gap: 6px; align-items: flex-start; line-height: 1.5; }
.agree input { margin-top: 3px; flex-shrink: 0; }

.btn-primary {
  margin-top: 4px;
  background: var(--vermillion);
  color: #fff;
  border: 0;
  border-radius: 8px;
  padding: 12px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, transform .05s;
  font-family: inherit;
}
.btn-primary:hover { background: var(--vermillion-dark); }
.btn-primary:active { transform: translateY(1px); }
.btn-primary:disabled { background: #ccc; cursor: not-allowed; }

.form-msg { margin: 4px 0 0; font-size: 13px; min-height: 18px; }
.form-msg.error { color: var(--vermillion); }
.form-msg.success { color: #2a8b5a; }

.divider {
  display: flex; align-items: center;
  color: var(--ink-3); font-size: 12px;
  margin: 20px 0 12px;
}
.divider::before, .divider::after {
  content: ""; flex: 1; height: 1px; background: var(--line);
}
.divider span { padding: 0 12px; }

.oauth { display: flex; gap: 10px; }
.oauth-btn {
  flex: 1;
  display: inline-flex; align-items: center; justify-content: center; gap: 6px;
  background: #fff; color: var(--ink-2);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px;
  font-size: 13px;
  cursor: not-allowed;
  opacity: .7;
  font-family: inherit;
}
.oauth-ico { font-size: 16px; }

.footer {
  margin: 20px 0 0;
  text-align: center;
  color: var(--ink-3);
  font-size: 12px;
}

/* 移动端收紧 */
@media (max-width: 480px) {
  .auth-card { padding: 24px 20px 20px; border-radius: 14px; }
  .brand-title { font-size: 20px; }
  body { padding: 16px 12px; }
  .oauth { flex-direction: column; }
}

/* 大屏稍微上浮 */
@media (min-height: 800px) {
  body { align-items: center; }
}