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

html, body {
  height: 100%;
  margin: 0;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  overflow: hidden; /* evita scroll innecesario */
}

/* ===== IMAGEN DE FONDO (desde HTML) ===== */
.background-img {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover; /* cubre toda la pantalla sin deformar */
  z-index: 0;
}

/* ===== CAPA OSCURA (overlay) ===== */
.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.6);
  z-index: 1;
  pointer-events: none; /* permite clics en los elementos de arriba */
}

/* ===== CONTENIDO CENTRADO ===== */
.center-content {
  position: fixed;  /* o absolute, pero fijo es más estable */
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 20px;
  pointer-events: auto; /* habilitamos clics en el contenido */
  width: 100%;
  max-width: 500px;
}

.logo-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 30px;
}

.logo {
  max-width: 300px;
  width: 100%;
  height: auto;
  filter: drop-shadow(0 0 15px rgba(255, 255, 255, 0.2));
}

.login-btn {
  padding: 16px 50px;
  background: linear-gradient(135deg, #0d6efd, #0d6efd);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 20px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
  text-decoration: none;
  display: inline-block;
}

.login-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
  background: linear-gradient(135deg, #224abe, #4e73df);
  color: white;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
  .logo {
    max-width: 280px;
  }

  .login-btn {
    padding: 14px 40px;
    font-size: 18px;
  }

  .center-content {
    padding: 15px;
  }
}