style.css

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}

html {
  font-size: 62.5%;
}

.editor-menu {
  width: 100%;
  height: 6rem;
  background-color: lightgrey;
  display: flex;
  justify-content: flex-start;
  align-items: center;
  padding: 5px 0 5px 10px;
}

.btn {
  color: #fff;
  border: none;
  outline: none;
  background-color: #17c;
  cursor: pointer;
  padding: 8px 7px;
  border-radius: 3px;
  font-size: 15px;
  margin-right: 8px;
  min-width: 50px;
  transition: all 0.3s;
}

.btn:hover {
  background-color: orangered;
}

.live {
  font-size: 16px;
  background-color: rgb(198, 240, 179);
  color: #242424;
  font-weight: bold;
  border: 2px solid orangered;
  padding: 5px 7px;
  display: flex;
  align-items: center;
  border-radius: 3px;
  cursor: pointer;
}

.live > * {
  cursor: pointer;
}

.container {
  position: absolute;
  bottom: 0px;
  top: 7rem;
  width: 100%;
  display: flex;
}

.left,
.right {
  height: 100%;
  width: 50%;
  border: 1px solid #d5d5d5;
}

.bar {
  width: 4px;
  height: 100%;
  background-color: #eee;
  cursor: pointer;
}

.right {
  flex: 1;
}

.logo {
  margin-right: 950px;
  font-size: 20px;
  margin-left: 15px;
  font-weight: 900;
  color: #17c;
  border-bottom: 2px dotted orangered;
  text-shadow: 0px 1px;
}

.editor {
  font-size: 18px;
  width: 100%;
  height: 100%;
  outline: none;
  border-color: #ccc;
  padding: 1rem 0 0 1rem;
}

i {
  margin-right: 5px;
}

.iframe {
  width: 100%;
  height: 100%;
  background-color: #fff;
  overflow-y: auto;
  white-space: pre;
  right: 0;
  padding: 4px;
}