index.css

body {
  margin: 0;
}

canvas {
  width: 100%;
  height: 100%;
}

.container {
  font-family: 'Roboto', sans-serif;
}

.input_container {
  display: flex;
  flex-direction: column;
  width: 80%;
  margin-left: 10%;
  margin-top: 50px;
}

.input_box {
  display: flex;
  margin-bottom: 1em;
}

.input_label {
  margin-right: 0.5em;
  font-family: Verdana, Geneva, Tahoma, sans-serif;
}

#forkongithub a {
  background: #000;
  color: #fff;
  text-decoration: none;
  font-family: arial, sans-serif;
  text-align: center;
  font-weight: bold;
  padding: 5px 40px;
  font-size: 1rem;
  line-height: 2rem;
  position: relative;
  transition: 0.5s;
  top: 30px;
}
#forkongithub a:hover {
  background: #c11;
  color: #fff;
}
#forkongithub a::before,
#forkongithub a::after {
  content: "";
  width: 100%;
  display: block;
  position: absolute;
  top: 1px;
  left: 0;
  height: 1px;
  background: #fff;
}
#forkongithub a::after {
  bottom: 1px;
  top: auto;
}
@media screen and (min-width: 800px) {
  #forkongithub {
    position: fixed;
    display: block;
    top: 0;
    right: 0;
    width: 200px;
    overflow: hidden;
    height: 200px;
    z-index: 9999;
  }
  #forkongithub a {
    width: 200px;
    position: absolute;
    top: 60px;
    right: -60px;
    transform: rotate(45deg);
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    -moz-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.8);
  }

  .input_container {
    width: 50%;
    margin-top: 1.5em;
  }
}