body {
    background: url("https://i.pinimg.com/1200x/85/67/d4/8567d4f5ffcbf1bbb958a02fbc862c95.jpg") no-repeat center center fixed;
    background-size: cover;   
}

.wrapper {
  --input-focus: #00A6A6;       /* Azul Turquesa */
  --font-color: #004E7C;        /* Azul Marino */
  --font-color-sub: #6ED3CF;    /* Verde Agua */
  --bg-color: rgba(242, 233, 228, 0.8); /* Arena Beige transparente */
  --bg-color-alt: rgba(110, 211, 207, 0.6); /* Verde Agua translúcido */
  --main-color: #004E7C;        /* Azul Marino */

  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  min-height: 100vh;  
}

/* switch card */
.switch {
  transform: translateY(-200px);
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 30px;
  width: 50px;
  height: 20px;
}

.card-side::before {
  position: absolute;
  content: 'Acceso';
  left: -70px;
  top: 0;
  width: 100px;
  text-decoration: none;
  color: #F2E9E4;
  font-weight: 600;
}

.card-side::after {
  position: absolute;
  content: 'Regístrate';
  left: 70px;
  top: 0;
  width: 100px;
  text-decoration: none;
  color: #F2E9E4;
  font-weight: 600;
}

.toggle {
  opacity: 0;
  width: 0;
  height: 0;
}

.slider {
  box-sizing: border-box;
  border-radius: 5px;
  border: 2px solid var(--main-color);
  box-shadow: 4px 4px var(--main-color);
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--bg-color);
  transition: 0.3s;
}

.slider:before {
  box-sizing: border-box;
  position: absolute;
  content: "";
  height: 20px;
  width: 20px;
  border: 2px solid var(--main-color);
  border-radius: 5px;
  left: -2px;
  bottom: 2px;
  background-color: var(--bg-color);
  box-shadow: 0 3px 0 var(--main-color);
  transition: 0.3s;
}

.toggle:checked + .slider {
  background-color: var(--input-focus);
}

.toggle:checked + .slider:before {
  transform: translateX(30px);
}

/* card */ 
.flip-card__inner {
  width: 300px;
  height: 350px;
  position: relative;
  background-color: transparent;
  perspective: 1000px;
  text-align: center;
  transition: transform 0.8s;
  transform-style: preserve-3d;
}

.toggle:checked ~ .flip-card__inner {
  transform: rotateY(180deg);
}

.toggle:checked ~ .flip-card__front {
  box-shadow: none;
}

.flip-card__front, .flip-card__back {
  padding: 20px;
  position: absolute;
  display: flex;
  flex-direction: column;
  justify-content: center;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  background: rgba(242, 233, 228, 0.85); /* Arena Beige translúcido */
  gap: 20px;
  border-radius: 10px;
  border: 2px solid var(--main-color);
  box-shadow: 4px 4px rgba(0, 78, 124, 0.6); /* Azul Marino suave */
}

.flip-card__back {
  width: 100%;
  transform: rotateY(180deg);
}

.flip-card__form {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
}

.title {
  margin: 20px 0 20px 0;
  font-size: 25px;
  font-weight: 900;
  text-align: center;
  color: var(--main-color);
}

.flip-card__input {
  width: 250px;
  height: 40px;
  border-radius: 5px;
  border: 2px solid var(--main-color);
  background-color: rgba(242, 233, 228, 0.7); /* Input translúcido */
  box-shadow: 2px 2px rgba(0, 78, 124, 0.4);
  font-size: 15px;
  font-weight: 600;
  color: var(--font-color);
  padding: 5px 10px;
  outline: none;
}

.flip-card__input::placeholder {
  color: var(--font-color-sub);
  opacity: 0.8;
}

.flip-card__input:focus {
  border: 2px solid var(--input-focus);
}

.flip-card__btn:active, .button-confirm:active {
  box-shadow: 0px 0px var(--main-color);
  transform: translate(3px, 3px);
}

.flip-card__btn {
  margin: 20px 0 20px 0;
  width: 120px;
  height: 40px;
  border-radius: 5px;
  border: 2px solid var(--main-color);
  background-color: rgba(110, 211, 207, 0.85); /* Verde Agua translúcido */
  box-shadow: 2px 2px rgba(0, 78, 124, 0.5);
  font-size: 17px;
  font-weight: 600;
  color: #004E7C; /* Azul Marino */
  cursor: pointer;
}