:root {
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --success: #22c55e;
  --warning: #facc15;
  --bg-dark: #0b0f19;
  --form-bg: #1e293b;
  --input-border: #334155;
  --input-focus: var(--primary);
  --text-muted: #94a3b8;
  --radius: 12px;
}

body {
  margin: 0;
  font-family: 'Inter', 'Segoe UI', Tahoma, sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: var(--bg-dark);
  color: #f1f5f9;
  transition: background 0.4s ease;
}

/* Contenedor principal */
.auth-container {
  background: var(--form-bg);
  padding: 32px;
  border-radius: var(--radius);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.3);
  width: 100%;
  max-width: 400px;
  animation: fadeUp 0.6s ease both;
}

/* Formularios */
.form-box {
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.form-box.hidden {
  display: none;
}

/* Inputs */
input, select {
  padding: 12px 14px;
  border: 1px solid var(--input-border);
  border-radius: var(--radius);
  outline: none;
  font-size: 15px;
  background-color: #0f172a;
  color: #f1f5f9;
  transition: border 0.3s ease, box-shadow 0.3s ease;
}
input::placeholder, select::placeholder {
  color: var(--text-muted);
}
input:focus, select:focus {
  border-color: var(--input-focus);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.2);
}

/* Botones */
button {
  background: var(--primary);
  color: white;
  border: none;
  padding: 12px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 15px;
  cursor: pointer;
  transition: background 0.3s ease, transform 0.2s ease, box-shadow 0.2s ease;
}
button:hover {
  background: var(--primary-dark);
  transform: scale(1.02);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.2);
}

/* Links */
.link {
  text-align: center;
  font-size: 14px;
  color: var(--text-muted);
}
.link a {
  color: var(--primary);
  text-decoration: none;
  font-weight: 500;
}
.link a:hover {
  text-decoration: underline;
}

/* Fecha de nacimiento */
.birth-container {
  display: flex;
  gap: 10px;
}

/* Tabs */
.tab {
  padding: 10px 16px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.3s ease;
}
.tab.active {
  background: var(--primary);
  color: white;
}
.tab:not(.active) {
  background: #334155;
  color: #f1f5f9;
}
.tab:hover {
  background: var(--primary-dark);
  color: white;
}

/* Animaciones */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Responsive */
@media (max-width: 480px) {
  .auth-container {
    padding: 24px;
    border-radius: 10px;
  }
  input, select {
    font-size: 14px;
  }
  button {
    font-size: 14px;
  }
}