style.css

* {
  box-sizing: border-box;
}

#editor-frame {
  position: fixed;
  left: 0;
  top: 0;
  width: 50%;
  height: 100%;
  background: rgb(252,252,252);
  z-index: 2;
}

#rs {
  position: fixed;
  left: 50%;
  width: 30px;
  margin-left: -15px;
  height: 100%;
  top: 0;
  background: rgba(0,255,0, 0.2);
  opacity: 0;
  cursor: col-resize;
  z-index: 999;
}

#rs:hover {
  opacity: 1;
  transition: 0.2s ease-in-out;
}

#editor {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  padding: 50px 100px;
  padding-bottom: 500px;

  font-size: 15px;
  font-family: "Source Code Pro", "Monaco", "Consolas", monospace;
  color: rgb(26,26,26);

  border: none;
  background: transparent;

  -webkit-font-smoothing: subpixel-antialiased;
}

#editor:focus {
  outline: none;
}

#preview {
  position: fixed;
  top: 0;
  left: 50%;
  height: 100%;
  width: 50%;
  overflow-y: scroll;
  z-index: 1;
  border-left: 1px solid #eee;
}

.markdown-body {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  padding: 45px;
  padding-bottom: 500px;
  -webkit-font-smoothing: subpixel-antialiased;
}

#file-list-frame {
  position: fixed;
  z-index: 999;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #f2f2f2;
  color: #444;
  font-size: 18px;
  text-align: center;
  margin: 0;
  padding: 0;
  font-family: "Source Code Pro", "Monaco", "Consolas", monospace;
}

#file-list {
  list-style-type: none;
  padding: 0;
}

#file-list > li > a {
  line-height: 2em;
  display: block;
}

#file-list > li > a:hover,
#file-list > li > a:focus {
  background: #ddd;
}

#file-list-search {
  padding: 10px;
  font-size: 18px;
  margin-top: 20px;
  color: #676767;
  background: rgba(255,255,255, 0.5);
  display: inline-block;
  width: 300px;
}