:root {
  --bg-deep:       #0d0519;
  --bg-base:       #1a1a2e;
  --accent-blue:   #51A0DE;
  --accent-purple: #7B68EE;
  --accent-amber:  #fac679;
  --text-primary:  rgba(204, 204, 204, 1);
  --text-secondary:rgba(150, 150, 150, 1);
  --glass-bg:      rgba(39, 39, 39, 0.55);
  --glass-border:  rgba(255, 255, 255, 0.07);
  --input-bg:      rgba(255, 255, 255, 0.05);
  --input-border:  rgba(255, 255, 255, 0.08);
  --error-color:   #f87171;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: 'PingFang SC', 'Microsoft YaHei', -apple-system, sans-serif;
  background: linear-gradient(180deg, var(--bg-deep) 0%, var(--bg-base) 100%);
  background-attachment: fixed;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.login-card {
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  border: 1px solid var(--glass-border);
  border-radius: 24px;
  padding: 40px 32px;
  width: 100%;
  max-width: 420px;
  text-align: center;
  box-shadow: 0 0 60px rgba(81, 160, 222, 0.06);
}

.login-icon {
  width: 64px;
  height: 64px;
  border-radius: 16px;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  margin: 0 auto 20px;
  box-shadow: 0 0 30px rgba(81, 160, 222, 0.2);
}

.login-title {
  font-size: 20px;
  font-weight: 600;
  color: #fff;
  margin-bottom: 6px;
}

.login-sub {
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.form-group {
  text-align: left;
  margin-bottom: 16px;
}

.form-label {
  display: block;
  font-size: 11px;
  color: var(--text-secondary);
  letter-spacing: 1px;
  margin-bottom: 6px;
}

.form-input {
  width: 100%;
  background: var(--input-bg);
  border: 1px solid var(--input-border);
  border-radius: 12px;
  padding: 12px 16px;
  font-size: 15px;
  color: var(--text-primary);
  outline: none;
  transition: border-color 0.2s;
  font-family: inherit;
}
.form-input::placeholder { color: rgba(150, 150, 150, 0.5); }
.form-input:focus { border-color: rgba(81, 160, 222, 0.4); }
.form-input.error { border-color: var(--error-color); }

#code-input {
  letter-spacing: 3px;
  font-size: 16px;
  text-transform: uppercase;
}

.btn-activate {
  width: 100%;
  background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
  color: #fff;
  border: none;
  border-radius: 50px;
  padding: 14px;
  font-size: 16px;
  font-weight: 500;
  cursor: pointer;
  margin-top: 8px;
  transition: opacity 0.2s;
  letter-spacing: 1px;
}
.btn-activate:hover:not(:disabled) { opacity: 0.9; }
.btn-activate:disabled { opacity: 0.5; cursor: not-allowed; }

.error-msg {
  margin-top: 12px;
  font-size: 12px;
  color: var(--error-color);
  min-height: 18px;
  text-align: center;
}

.success-msg {
  margin-top: 12px;
  font-size: 13px;
  color: var(--accent-amber);
  text-align: center;
}

.invite-note {
  margin-top: 24px;
  font-size: 11px;
  color: rgba(150, 150, 150, 0.5);
  letter-spacing: 1px;
  border-top: 1px solid var(--glass-border);
  padding-top: 20px;
}

.btn-activate.loading::after {
  content: '';
  display: inline-block;
  width: 14px;
  height: 14px;
  border: 2px solid rgba(255,255,255,0.3);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  margin-left: 8px;
  vertical-align: middle;
}
@keyframes spin { to { transform: rotate(360deg); } }