body {
    padding: 0;
    margin: 0;
    display: grid;
    place-items: center;
    background-image: linear-gradient(to right, red, blue, green);
    background-image: -moz-linear-gradient(to right, red, blue, green);
    
    
}

.main {
  margin-top: 10%;
  height: 750px;
  width: 600px;
  background: #222;
  border-radius: 30px;
  display: grid;
  place-items: center;
  font-family: verdana;
}

#box {
  height: 40px;
  width: 80%;
  border: none;
  outline: none;
  outline: none;
  border-radius: 40px;
  text-align: center;
}

#title {
  color: azure;
  margin-left: auto;
  margin-right: auto;
  width: 5.5em;

}

#clr-sol {
  width: auto;
  height: 50px;
  border-radius: 40px;
  background-color: rgb(0,0,0);
  border: 3px solid;
  margin-bottom: 10px;
  margin-left: auto;
  margin-right: auto;
  width: 30em;
}

#clr-guess {
  width: auto;
  height: 50px;
  border-radius: 40px;
  background-color: rgb(0,0,0);
  border: 3px solid;
  margin-top: 20px;
  margin-left: auto;
  margin-right: auto;
  width: 30em;
}

#btn_submit {
  display:block;
  width: 15em;
  height: 30px;
  background-color: #666;
  margin-left: auto;
  margin-right: auto;
  margin-top: 1em;
  border-radius: 20px;
}

/* CSS property for slider */
input[type="range"] {
  -webkit-appearance: none;
  margin-top: 10%;
  height: 15px;
  width: 80%;
  border-radius: 50px;
  outline: none;
}
/* CSS property for slider thumb */
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  height: 40px;
  width: 40px;
  border-radius: 30px;
  background: grey;
  cursor: pointer;
}

/* CSS property for slider thumb on firefox */
input[type="range"]::-moz-range-thumb {
  width: 40px;
  height: 40px;
  background: grey;
  border-radius: 30px;
  cursor: pointer;
}

.main #clr-1 {
  background: linear-gradient(90deg, #000, red);
}

.main #clr-2 {
  background: linear-gradient(90deg, #000, green);
}

.main #clr-3 {
  background: linear-gradient(90deg, #000, blue);
}