:root {
  --purple-50: #f5f0ff;
  --purple-100: #ece3ff;
  --purple-200: #d9c8ff;
  --purple-300: #c3a8f7;
  --purple-400: #a98ae8;
  --purple-500: #8f6fd6;
  --purple-600: #7757bd;
  --purple-700: #6147a0;
  --text: #3a3550;
  --text-light: #7b7496;
  --bg: linear-gradient(160deg, #f3ecff 0%, #e9dcff 45%, #fdf3ff 100%);
  --card-bg: #ffffff;
  --ok: #5b8c6f;
  --ok-bg: #e7f4ec;
  --bad: #b0565f;
  --bad-bg: #fbe9eb;
  --radius: 16px;
  --shadow: 0 12px 34px rgba(97, 71, 160, 0.14);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  font-family: "PingFang SC", "Microsoft YaHei", "Segoe UI", system-ui, sans-serif;
  color: var(--text);
}

body {
  background: var(--bg);
  background-attachment: fixed;
}

/* ---------- login ---------- */
.auth-bg {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.auth-card {
  width: 100%;
  max-width: 400px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px 36px;
}

.brand { text-align: center; margin-bottom: 28px; }

.brand-mark {
  width: 56px;
  height: 56px;
  margin: 0 auto 14px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--purple-400), var(--purple-600));
  color: #fff;
  font-size: 26px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 8px 18px rgba(119, 87, 189, 0.35);
}

.brand h1 {
  margin: 0;
  font-size: 20px;
  letter-spacing: 1px;
}

.subtitle {
  margin: 8px 0 0;
  color: var(--text-light);
  font-size: 13px;
}

/* ---------- fields ---------- */
.field { display: block; margin-bottom: 16px; }

.field span {
  display: block;
  font-size: 13px;
  color: var(--text-light);
  margin-bottom: 6px;
}

.field input {
  width: 100%;
  padding: 11px 14px;
  font-size: 15px;
  border: 1.5px solid var(--purple-200);
  border-radius: 10px;
  background: var(--purple-50);
  outline: none;
  transition: border-color .2s, box-shadow .2s, background .2s;
}

.field input:focus {
  border-color: var(--purple-500);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(143, 111, 214, 0.18);
}

/* ---------- captcha ---------- */
.captcha-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.captcha-row input { flex: 1; }

.captcha-question {
  background: var(--purple-100);
  color: var(--purple-700);
  border-radius: 8px;
  padding: 9px 12px;
  font-size: 15px;
  font-weight: 600;
  white-space: nowrap;
}

/* ---------- buttons ---------- */
.btn {
  border: none;
  cursor: pointer;
  font-size: 15px;
  border-radius: 10px;
  padding: 11px 22px;
  transition: transform .1s, box-shadow .2s, background .2s;
}

.btn:disabled { opacity: .6; cursor: not-allowed; }

.btn.primary {
  background: linear-gradient(135deg, var(--purple-400), var(--purple-600));
  color: #fff;
  box-shadow: 0 6px 16px rgba(119, 87, 189, 0.35);
}

.btn.primary:hover:not(:disabled) {
  box-shadow: 0 8px 22px rgba(119, 87, 189, 0.45);
  transform: translateY(-1px);
}

.btn-block { width: 100%; margin-top: 8px; }

.btn.ghost {
  background: transparent;
  color: var(--purple-600);
  padding: 8px 14px;
  font-size: 13px;
  border: 1.5px solid var(--purple-300);
}

.btn.ghost:hover { background: var(--purple-100); }

/* ---------- alert ---------- */
.alert {
  padding: 11px 14px;
  border-radius: 10px;
  font-size: 14px;
  margin-bottom: 18px;
}

.alert.error {
  background: var(--bad-bg);
  color: var(--bad);
}

/* ---------- main page ---------- */
.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 26px;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--purple-100);
}

.brand.small { display: flex; align-items: center; gap: 10px; margin: 0; }

.brand.small .brand-mark {
  width: 34px;
  height: 34px;
  font-size: 16px;
  margin: 0;
}

.brand-name { font-size: 16px; font-weight: 600; }

.container {
  max-width: 640px;
  margin: 40px auto;
  padding: 0 20px;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 30px 28px;
}

.card h2 { margin: 0 0 6px; font-size: 19px; }

.hint {
  margin: 0 0 22px;
  color: var(--text-light);
  font-size: 13.5px;
  line-height: 1.6;
}

.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }

.card .btn.primary { margin-top: 6px; width: 100%; }

/* ---------- result ---------- */
.result {
  margin-top: 22px;
  padding: 16px 18px;
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.result.ok { background: var(--ok-bg); color: var(--ok); }
.result.bad { background: var(--bad-bg); color: var(--bad); }

.result-title { font-size: 16px; font-weight: 600; }

.result span { font-size: 14px; }

.footer {
  text-align: center;
  color: var(--text-light);
  font-size: 12px;
  padding: 20px 0 30px;
}

@media (max-width: 520px) {
  .form-grid { grid-template-columns: 1fr; }
  .topbar { padding: 12px 16px; }
  .card { padding: 22px 18px; }
}