/* ========================================
   BOTONES — SISTEMA .btn
   Variantes: --primary (relleno, un solo por pantalla),
   --secondary (borde con gradiente), --ghost (enlace terciario).
   Tamaños: base, --sm, --lg.
   Efectos: brillo que sigue al cursor (--mx/--my, ver js/effects.js),
   shimmer en hover, flecha desplazable (.btn-arrow), magnetismo leve
   solo con puntero fino (también en effects.js). Todo se apaga con
   prefers-reduced-motion. Transiciones con propiedades explícitas:
   nunca `transition: all`.
   ======================================== */

.btn {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  isolation: isolate;
  overflow: hidden;
  min-height: 48px;
  padding: 0 var(--sp-6);
  border-radius: var(--r-pill);
  border: 1px solid transparent;
  font-family: var(--font-secondary);
  font-weight: 600;
  font-size: var(--fs-base);
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  color: var(--text-light);
  transition: transform var(--dur-fast) var(--ease-out),
              box-shadow var(--dur-fast) var(--ease-out),
              border-color var(--dur-fast) var(--ease-out),
              background-color var(--dur-fast) var(--ease-out),
              opacity var(--dur-fast) var(--ease-out);
}

.btn--sm {
  min-height: 40px;
  padding: 0 var(--sp-4);
  font-size: var(--fs-sm);
}

.btn--lg {
  min-height: 52px;
  padding: 0 var(--sp-8);
  font-size: var(--fs-lead);
}

/* --- Brillo que sigue al cursor (radial-gradient posicionado con --mx/--my) --- */
.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  opacity: 0;
  background: radial-gradient(140px circle at var(--mx, 50%) var(--my, 50%),
              rgba(255, 255, 255, 0.35), transparent 70%);
  transition: opacity var(--dur-fast) var(--ease-out);
  pointer-events: none;
}

/* --- Shimmer: barrido diagonal al hacer hover --- */
.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  z-index: -1;
  background: linear-gradient(115deg, transparent 20%, rgba(255, 255, 255, 0.22) 50%, transparent 80%);
  transform: translateX(-120%);
  transition: transform var(--dur-slow) var(--ease-out);
  pointer-events: none;
}

@media (hover: hover) {
  .btn:hover::before { opacity: 1; }
  .btn:hover::after { transform: translateX(120%); }
}

/* --- Flecha desplazable (solo en botones que la incluyan, ej. CTA del hero) --- */
.btn-arrow {
  display: inline-block;
  transition: transform var(--dur-fast) var(--ease-out);
}

@media (hover: hover) {
  .btn:hover .btn-arrow {
    transform: translateX(4px);
  }
}

/* --- Variante primaria: relleno con gradiente de marca --- */
.btn--primary {
  background: linear-gradient(135deg, var(--primary-accent), var(--secondary-accent));
  border-color: rgba(255, 255, 255, 0.15);
  box-shadow: var(--shadow-glow-accent);
}

@media (hover: hover) {
  .btn--primary:hover {
    box-shadow: var(--shadow-glow-accent-lg);
    transform: translateY(-2px);
  }
}

.btn--primary:active {
  transform: translateY(0) scale(0.98);
  box-shadow: var(--shadow-glow-accent);
}

/* --- Variante secundaria: borde con gradiente sobre fondo oscuro --- */
.btn--secondary {
  background: linear-gradient(var(--primary-dark), var(--primary-dark)) padding-box,
              var(--gradient-brand) border-box;
  border: 1px solid transparent;
  color: var(--text-light);
}

@media (hover: hover) {
  .btn--secondary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
  }
}

.btn--secondary:active {
  transform: translateY(0);
}

/* --- Variante ghost: terciaria, tipo enlace con borde hairline --- */
.btn--ghost {
  background: transparent;
  border-color: var(--border-hairline-strong);
  color: var(--accent-text);
}

@media (hover: hover) {
  .btn--ghost:hover {
    border-color: var(--accent-text);
    background: rgba(199, 125, 240, 0.08);
  }
}

/* --- Estados --- */
.btn:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
  box-shadow: 0 0 0 6px var(--cyan-10);
}

.btn[disabled],
.btn.is-disabled {
  opacity: 0.7;
  cursor: not-allowed;
  box-shadow: none;
}

.btn[disabled]::before,
.btn[disabled]::after {
  display: none;
}

/* Cargando: reutiliza el spinner que ya trae el botón de envío del formulario */
.btn .form-spinner {
  display: none;
}

.btn[disabled] .form-spinner {
  display: inline-block;
}

.btn.is-success {
  background: linear-gradient(135deg, var(--success), var(--teal));
  border-color: transparent;
}

/* --- Magnetismo leve: solo con puntero fino, JS setea --mx/--my y transform --- */
@media (pointer: coarse) {
  .btn {
    transform: none !important;
  }
}