index.css

html,
body {
  height: 100%;
  user-select: none;
  -webkit-user-select: none;
  font-family: Avenir;
  font-size: 1rem;
}

* {
  -webkit-touch-callout: none; /* iOS Safari */
  -webkit-user-select: none; /* Safari */
  -khtml-user-select: none; /* Konqueror HTML */
  -moz-user-select: none; /* Old versions of Firefox */
  -ms-user-select: none; /* Internet Explorer/Edge */
  user-select: none; /* Non-prefixed version, currently supported by Chrome, Opera and Firefox */
}

#container {
  display: flex;
  flex-flow: row;
  align-items: center;
  justify-content: space-evenly;
  min-height: 95%;
}

#instructions {
  display: flex;
  flex-flow: column;
  justify-content: center;
}

#buttons {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  align-items: center;
  margin: 1rem 0;
}
button {
  font-size: 1rem;
  height: 3rem;
  width: 90%;
  outline: none;
  border: 1px solid transparent;
  border-radius: 4rem;
  background-color: rgb(236, 171, 85);
  margin: 1rem 0;
  box-shadow: 0px 8px 15px rgba(0, 0, 0, 0.1);
  cursor: pointer;
  transition: all 0.3s ease 0s;
}
button:active {
  border-color: black;
  transform: translateY(-4px);
}

#touchArea {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.5rem;
  text-align: center;
  border: 5px solid transparent;
  border-radius: 10px;
  width: 90vh;
  height: 90vh;
  /* Add this again to add lines
  background-image: linear-gradient(white 1px, transparent 0),
    linear-gradient(90deg, white 1px, transparent 0);
    */
  background-size: 6.6667% 100%;
  touch-action: none;
  cursor: pointer;
  background-color: rgb(255, 228, 77);
}

@media screen and (max-width: 1200px) {
  #container {
    flex-direction: column;
    justify-content: space-evenly;
  }

  #touchArea {
    width: 80vw;
    height: 80vw;
  }
}

@media screen and (max-width: 600px) {
  #container {
    justify-content: flex-start;
  }

  #buttons {
    margin: 0.5rem 0;
  }
  button {
    margin: 0.5rem 0;
  }
  #touchArea {
    width: 90vw;
    height: 90vw;
  }
}

@media screen and (max-height: 600px) {
  h3 {
    margin: 0;
  }
  button {
    height: 2rem;
    font-size: 0.8rem;
  }
}