style.css

@import url("https://fonts.googleapis.com/css2?family=Righteous&display=swap");

body {
  font-family: "Righteous", cursive;
  background-color: rgb(4, 86, 119);
  background-image: url('blue-background.jpg');
  color: rgb(245, 245, 245);
}

#score {
  text-align: center;
  margin: 0;
  font-size: 40px;
}

.container {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding-top: 20px;
}

.btn-container {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 30px;
}

input {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  outline: inherit;
  font: inherit;
  text-transform: uppercase;
  color: rgb(245, 245, 245);
}

@media only screen and (max-width: 350px) {
  .container {
    height: 87vh;
  }
  input {
    font-size: 12px;
  }
  .arrow-container {
    margin-top: -10px;
    padding: 0;
  }
  #gameCanvas {
    margin-bottom: -10px;
  }
}

.active {
  color: #ebc000;
}

#start,
#restart {
  margin: 0 7.5px;
}

.difficulty {
  text-align: center;
  margin-left: 15px;
}

#gameCanvas {
  box-shadow: 12px 12px 40px black;
  border-radius: 4px;
  padding: 0;
  margin: 0;
  background: #fff;
}

.arrow-container {
  display: flex;
  justify-content: center;
  align-items: center;
  align-self: center;
  flex-direction: column;
  margin-top: 40px;
  margin-bottom: 0;
}

button {
  background: none;
  border: none;
  padding: 0;
  cursor: pointer;
  outline: inherit;
  font-size: 50px;
  margin: -10px 12px;
}

.hovering-btn:hover,
.hoverin-btn:active {
  color: #ebc000;;
}