/* ═══════════════════════════════════════════════════════════════
   SABER PRO / TYT  ·  Estilos UNAD
   Paleta institucional:
     Naranja  #f47920
     Azul     #004669
   ═══════════════════════════════════════════════════════════════ */

/* ── Variables ─────────────────────────────────────────────────── */
:root {
  --unad-orange:      #f47920;
  --unad-orange-dark: #d4641a;
  --unad-blue:        #004669;
  --unad-blue-dark:   #003250;
  --unad-blue-light:  #e8f0f5;
  --unad-gray-bg:     #f5f6f8;
  --unad-gray-border: #dde3ea;
  --unad-text:        #1a2b38;
  --unad-text-muted:  #5c7080;
  --radius-card:      14px;
  --radius-input:     8px;
  --shadow-card:      0 4px 24px rgba(0,70,105,.10);
  --transition:       .2s ease;
}

/* ── Reset mínimo ───────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; }

/* ── Body / fondo ───────────────────────────────────────────────── */
body {
  margin: 0;
  min-height: 100vh;
  background: var(--unad-gray-bg);
  background-image:
    radial-gradient(ellipse 80% 50% at 50% -10%, rgba(0,70,105,.08) 0%, transparent 70%);
  display: flex;
  flex-direction: column;
  font-size:18px;
}

/* ── Header ─────────────────────────────────────────────────────── */
.st-header {
  background: #fff;
  padding: 0 2rem;
  height: 64px;
  display: flex;
  align-items: center;
  gap: 1rem;
  box-shadow: 0 2px 8px rgba(0,0,0,.18);
}
.st-header__logo {
  height: 38px;
  width: auto;
}
.st-header__title {
  color: #004669;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: .01em;
  line-height: 1.2;
  border-left: 2px solid var(--unad-orange);
  padding-left: 1rem;
  margin: 0;
}
.st-header__subtitle {
  display: block;
  font-size: .75rem;
  font-weight: 400;
  color: #004669;
}

/* ── Layout principal ───────────────────────────────────────────── */
.st-main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2.5rem 1rem;
}

/* ── Tarjeta contenedora ────────────────────────────────────────── */
.st-card {
  background: #fff;
  border-radius: var(--radius-card);
  box-shadow: var(--shadow-card);
  width: 100%;
  max-width: 480px;
  overflow: hidden;
}

.st-card__head {
  background: linear-gradient(135deg, var(--unad-blue) 0%, var(--unad-blue-dark) 100%);
  padding: 1.75rem 2rem 1.5rem;
  position: relative;
}
.st-card__head::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 4px;
  background: var(--unad-orange);
}
.st-card__head-title {
  color: #fff;
  font-size: 1.2rem;
  font-weight: 700;
  margin: 0 0 .3rem;
}
.st-card__head-sub {
  color: rgba(255,255,255,.7);
  font-size: .82rem;
  margin: 0;
}

.st-card__body {
  padding: 2rem;
}

/* ── Grupos de campo ────────────────────────────────────────────── */
.st-field {
  margin-bottom: 1.25rem;
}
.st-field label {
  display: block;
  font-size: .82rem;
  font-weight: 600;
  color: var(--unad-blue);
  margin-bottom: .45rem;
  letter-spacing: .02em;
  text-transform: uppercase;
}
.st-field input {
  width: 100%;
  padding: .7rem 1rem;
  border: 1.5px solid var(--unad-gray-border);
  border-radius: var(--radius-input);
  font-size: .97rem;
  color: var(--unad-text);
  background: #fff;
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}
.st-field input:focus {
  border-color: var(--unad-orange);
  box-shadow: 0 0 0 3px rgba(244,121,32,.15);
}
.st-field input.is-invalid {
  border-color: #dc3545;
  box-shadow: 0 0 0 3px rgba(220,53,69,.12);
}
.st-field__hint {
  display: block;
  margin-top: .35rem;
  font-size: .78rem;
  color: var(--unad-text-muted);
}
.st-field__error {
  display: none;
  margin-top: .35rem;
  font-size: .78rem;
  color: #dc3545;
  font-weight: 500;
}
.st-field input.is-invalid + .st-field__hint { display: none; }
.st-field input.is-invalid ~ .st-field__error { display: block; }

/* ── Botones ────────────────────────────────────────────────────── */
.st-btn-group {
  display: flex;
  gap: .75rem;
  margin-top: 1.75rem;
}
.st-btn {
  flex: 1;
  padding: .72rem 1rem;
  border: none;
  border-radius: var(--radius-input);
  font-size: .95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), opacity var(--transition);
  letter-spacing: .01em;
}
.st-btn:active { transform: scale(.97); }
.st-btn--primary {
  background: var(--unad-orange);
  color: #fff;
}
.st-btn--primary:hover { background: var(--unad-orange-dark); }
.st-btn--primary:disabled {
  opacity: .55;
  cursor: not-allowed;
  transform: none;
}
.st-btn--secondary {
  background: var(--unad-blue-light);
  color: var(--unad-blue);
}
.st-btn--secondary:hover { background: #d0dfe9; }

/* ── Footer ─────────────────────────────────────────────────────── */
.st-footer {
  background: var(--unad-blue-dark);
  color: rgba(255,255,255,.5);
  text-align: center;
  font-size: .75rem;
  padding: .9rem 1rem;
  letter-spacing: .03em;
}

/* ── Responsive ─────────────────────────────────────────────────── */
@media (max-width: 520px) {
  .st-header { padding: 0 1rem; }
  .st-header__title { font-size: .88rem; }
  .st-card__body { padding: 1.5rem; }
  .st-btn-group { flex-direction: column; }
}