/* Resets */
:root {
  --main-color: #ff9d0a;
  --light-color: #eee;
  --dark-color: #444;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: Arial, Helvetica, sans-serif;
  min-height: 100vh;
  text-align: center;
  color: var(--dark-color);
}

/* Game */
body > div {
  margin: 1rem;
}
/* Username */
#un label {
  display: block;
}
#un input:focus {
  background-color: var(--main-color);
  color: #fff;
  border: none;
  box-shadow: none;
  font-weight: bold;
}

/* Difficulty */
#diff label {
  display: block;
}
#diff input[type="radio"]:checked + span {
  color: var(--main-color);
}

/* Timer */
#game {
  position: relative;
}
#timer {
  position: absolute;
  top: 1rem;
  right: 1rem;
  margin: 0.5rem;
  border: 1px solid #000;
  border-radius: 10%;
  width: 3rem;
  height: 3rem;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 2rem;
  background-color: var(--light-color);
}

/* Card Table */
#table {
  display: grid;
  gap: 10px;
}
#table.easy {
  grid-template-columns: repeat(4, 1fr);
}
#table.medium {
  grid-template-columns: repeat(6, 1fr);
}
#table.hard {
  grid-template-columns: repeat(8, 1fr);
}
#table.expert {
  grid-template-columns: repeat(10, 1fr);
}

img {
  position: absolute;
  top: 10%;
  left: 10%;
  width: 80%;
  height: 80%;
}

/* Cards */
.card {
  box-shadow: 1px 1px 6px -3px var(--dark-color);
  border-radius: 10%;
}

/* Flip effect */
#table {
  perspective: 1000px;
}

.card {
  position: relative;
  padding-top: 100%;
  transform-style: preserve-3d;
  transition: transform 0.7s;
}
.front,
.back {
  backface-visibility: hidden;
}

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

.front {
  transform: rotateY(180deg);
}

/* Leaderboard */
#leaderboard h2 {
  margin: 1rem;
}
#leaderboardDiffBtns {
  overflow: hidden;
  margin: 0.5rem 0;
}
#leaderboard .width {
  float: left;
  width: 50%;
  padding: 0.2rem 0.2rem;
}
#leaderboard input[type="button"] {
  min-height: 1.5rem;
  width: 100%;
  /* stroke: none; */
}
#leaderboard table{
  border-collapse: collapse;
  width: 100%;
}
#leaderboard tr th {
  border: 1px solid #000;
  height: 2rem;
  background-color: var(--light-color);
  color: var(--dark-color);
}
#leaderboard tr td {
  border: 1px solid #000;
  height: 2rem;
}
#leaderboard input[type="button"] {
  background-color: #fff;
  border: 1px solid var(--dark-color);
  border-radius: 2px;
}
#leaderboard input[type="button"]:focus {
  outline: none;
}
.target {
  background-color: var(--main-color) !important;
  color: #fff;
  font-weight: bold;
}

footer {
  padding: 1rem 0;
  background-color: var(--dark-color);
  color: #fff;
}

/* Responsivenes */
/* Mobile */
#table, #un, #diff, .container {
margin: 1rem auto;
max-width: 65vh;
}
#un, #diff {
  text-align: center;
}
#un label {
  margin: 0.5rem;
}
#diff label {
  margin: 0.5rem;
}

/* Tablet */
@media only screen and (min-width: 600px) {
  #leaderboard .width {
    width: 25%;
    padding: 0rem 0.2rem;
  }
  /* #leaderboard input[type="button"] {
    width: 25%;
  } */
  #table, #un, #diff, .container {
    max-width: 75vh;
  }
  
  #un, #diff {
    text-align: left;
  }
  
  #un label, #diff label {
    display: inline-block;
    width: 40%;
    margin: 0;
  }
}

/* Desktop */
@media only screen and (min-width: 950px) {
  body>div {
    overflow: hidden;
    margin: 0;
  }
  
  *[class*=col] {
    float: left;
    width: 50%;
    min-width: 300px;
    overflow: hidden;
    padding: 1rem;
  }

  footer {
    position: absolute;
    width: 100%;
  }
  
}