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

:root {
  --off-white: #effffb;
  --green: #50d890;
  --blue: #4f98ca;
  --dark: #272727;
}

body {
  background-color: var(--off-white);
  color: var(--dark);
}

header {
  text-align: center;
}

h1 {
  text-align: center;
  margin: 2rem auto;
}

p {
  display: inline-block;
}

p,
#score {
  font-size: 1.5rem;
  font-weight: bold;
}

p,
button {
  margin: 0 auto 1rem auto;
}

button {
  padding: 5px 10px;
  margin-left: 20px;
  background-color: var(--blue);
  border-radius: 7px;
}

p,
#restart-game {
  text-decoration: none;
  font-size: 1.25rem;
}

#restart-game {
  color: white;
}

.cards-container {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
  margin: 0 20%;
}

.card-container {
  width: 150px;
  height: 150px;
  margin: 10px;
  perspective: 1000px;
}

.card-container.flipped .card {
  transform: rotateY(180deg);
}

.card {
  width: 100%;
  height: 100%;
  position: relative;
  transition: transform 1s;
  transform-style: preserve-3d;
}

.card-front,
.card-back {
  width: 100%;
  height: 100%;
  position: absolute;
  backface-visibility: hidden;
  border-radius: 7px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.card-front {
  background-color: var(--green);
  color: white;
  text-align: center;
}

.card-back {
  background-color: var(--blue);
  color: var(--dark);
  transform: rotateY(180deg);
}