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

#navbar {
  height: 67px;
  padding: 10px;
  padding-bottom: 20px;
  background-image: url("../img/BG_nav-bt.svg");
  background-repeat: repeat;
  float: left;
}

#separator{
  width: 65px;
  height: 67px;
  padding-top: 18px;
  background-image: url("../img/BG_nav-sep.svg");
  float: left;
}

#navbar2 {
  height: 67px;
  padding-top: 18px;
  background-image: url("../img/BG_nav.svg");
  overflow: hidden;
}

#message {
  font-weight: 900;
}

.button {
  margin-right: 10px;
  padding: 5px;
  padding: 5px 10px 5px 10px;
  border-radius: 5px;
  border-width: 0;

  position: relative;
  display: inline-block;

  color: white;
  font-weight: bolder;
  font-size: large;
  text-decoration: none;
  background: linear-gradient(rgb(0, 0, 255), rgb(173, 216, 230));
  box-shadow: 0px 0px 2.5px black;  
}

.button:after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: calc(100% - 4px);
  height: 50%;
  background: linear-gradient(
    rgba(255, 255, 255, 0.8),
    rgba(255, 255, 255, 0.2)
  );
  border-radius: 3.5px;
}

.button:hover {
  color: white;
  background: linear-gradient(rgb(128, 128, 255), rgb(0, 255, 255));
  box-shadow: 0px 0px 5px rgb(0, 255, 255);
}

.button:active {
  color: white;
  background: linear-gradient(rgb(0, 0, 128), rgb(0, 128, 128));
  box-shadow: 0px 0px 0px;
}

#gameField {
  width: 90%;
  margin: auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
}

.container {
  width: 100%;
  /* border: 1px solid black; */
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  perspective: 1000px;
}

.card {
  width: 100px;
  height: 100px;
  margin: 5px;
  background-color: blue;
  color: white;
  display: flex;
  justify-content: center;
  text-align: center;
  transition-duration: 0.5s;
  transform-style: preserve-3d;
}

.card-back,
.card-front {
  width: 100%;
  position: absolute;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
}

/* hidden */
.card-back {
  /* display: none; */
  font-size: xxx-large;
  transform: rotateY(180deg);
}

/* content/flipped/revealed */
/* .card-front {
} */

.flip-animation {
  transform: rotateY(180deg);
}

.intro-slide-up {
  animation: slide-up 1s;
}

.intro-slide-left {
  animation: slide-left 2s;
}

.intro-flip {
  animation: rotateIntoView 1s;
}

@keyframes slide-up {
    0% {
      opacity: 0;
      transform: translateY(50px);
    }
    100% {
      opacity: 1;
      transform: translateY(0);
    }
}

@keyframes slide-left {
    0% {
      opacity: 0;
      transform: translateX(100%);
    }
    100% {
      opacity: 1;
      transform: translateX(0);
    }
}

@keyframes rotateIntoView {
    0% {
      opacity: 0;
      transform: rotateX(90deg);
    }
    100% {
      opacity: 1;
      transform: rotateX(0deg);
    }
}