#editor {
  position: relative;
  width: 500px;
  height: 400px;
}
.run-button {
  display: inline-block;
  background: #8f7a66;
  border-radius: 3px;
  padding: 0 20px;
  text-decoration: none;
  color: #f9f6f2;
  height: 40px;
  line-height: 42px;
  display: block;
  text-align: center;
  float: right; }

@media screen and (max-width: 520px) {
  #editor {
    width: 280px;
  }
  .run-button {
    width: 42%;
    padding: 0;
    display: block;
    box-sizing: border-box;
    margin-top: 2px; }
}

#editor {
  position: relative;
  width: 500px;
  height: 400px;
}
.run-button {
  margin-left: 5px;
  display: inline-block;
  background: #8f7a66;
  border-radius: 3px;
  padding: 0 20px;
  text-decoration: none;
  color: #f9f6f2;
  height: 40px;
  line-height: 42px;
  display: block;
  text-align: center;
  float: right; }

@media screen and (max-width: 520px) {
  #editor {
    width: 280px;
  }
  .run-button {
    width: 42%;
    padding: 0;
    display: block;
    box-sizing: border-box;
    margin-top: 2px; }
}

Add margin between editor buttons
Add margin between editor buttons
