index.css

html {
  background: #eee;
  font: 16px/1.6 "Open Sans","Helvetica Neue",Helvetica,Arial,sans-serif;
}
h1 {
  text-align: center;
}
a {
  color: #ee6723;
  text-decoration: none;
  -webkit-transition: color .1s;
  transition: color .1s;
}
a:hover,
a:active {
  color: #ce5010;
  text-decoration: underline;
}
.github-ribbon {
  position: absolute;
  right: 0px;
  top: 0px;
  width: 150px;
  height: 150px;
  overflow: hidden;
  z-index: 9999;
}
.github-ribbon a {
  display: inline-block;
  width: 200px;
  overflow: hidden;
  padding: 6px 0px;
  text-align: center;
  transform: rotate(45deg);
  text-decoration: none;
  color: rgb(255, 255, 255);
  position: inherit;
  top: 45px;
  right: -40px;
  border-width: 1px 0px;
  border-style: dotted;
  border-color: rgba(255, 255, 255, 0.701961);
  font-style: normal;
  font-variant: normal;
  font-weight: 700;
  font-stretch: normal;
  font-size: 13px;
  line-height: normal;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  box-shadow: rgba(0, 0, 0, 0.498039) 0px 2px 3px 0px;
  background-color: rgb(170, 0, 0);
  background-image: linear-gradient(rgba(0, 0, 0, 0), rgba(0, 0, 0, 0.14902));
}

#app div {
  display: inline-block;
  min-width: 33%;
  overflow: hidden;
  text-align: center;
  padding: 20px 0;
  border: 1px solid #ddd;
  margin: 0;
  float: left;
}

#app a {
  display: block;
}

#app a:hover {
  text-decoration: none;
}

iframe {
  width: 80%;
}