.demo {
  display: inline-block;
  width: 24%;
  padding: 10px;
  box-sizing: border-box;
}
.demo textarea {
  box-sizing: border-box;
  font-family: "Roboto";
  font-size: 0.9em;
  height: 32px;
  padding: 6px 0px;
  resize: none;
  text-align: center;
  width: 100%;
  border: 1px solid rgba(0, 0, 0, 0.2);
}

.markup {
  margin: 3em 0;
}
.effects {
  margin: 3em 0;
}
.license {
  margin-top: 2em;
}

#forkongithub {
  display: none;
}
#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;
  -webkit-transition: 0.5s;
  transition: 0.5s;
}
#forkongithub a:hover,
#forkongithub a:focus,
#forkongithub a:active {
  background: #2098D1;
  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 only screen and (max-width: 959px) {
  .demo {
    width: 32.5%;
  }
}
@media only screen and (max-width: 659px) {
  .demo {
    width: 49%;
  }
  .intro,
  .download {
    max-width: 100%;
    width: 100%;
  }
}
@media only screen and (max-width: 360px) {
  .demo {
    width: 100%;
  }
}

@media screen and (min-width: 1280px) {
  #forkongithub {
    position: absolute;
    display: block;
    top: 0;
    right: 0;
    width: 200px;
    overflow: hidden;
    height: 200px;
  }
  #forkongithub a {
    width: 200px;
    position: absolute;
    top: 60px;
    right: -60px;
    -webkit-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
    box-shadow: 4px 4px 10px rgba(0, 0, 0, 0.8);
  }
  .ad__preview a {
    display: inline-block;
    width: 32%;
  }
  .ad__preview .second {
    margin: 0 2%;
  }
}
.ad {
  margin-top: 2em;
  text-align: center;
}