index.css

body {
    background-color: #eee8d5;
    max-width: 1200px;
    margin: 0px auto;
    padding: 5px;
    color: #073642;
}
h1, p{
    font-family: sans-serif;
    padding: 0px 10px;
}
#content {
    width: 100%;
    padding: 0px;
    height: 450px;
}
#content::after {
    content: ".";
    visibility: hidden;
    display: block;
    height: 0;
    clear: both;
}

#left, #right, textarea {
    width: 50%;
    height: 100%;
    padding: 10px;
    box-sizing: border-box;
    font-family: monospace;
}

#left {
    float: left;
}

#right {
    float: right;
}

#simple-sub-input, #simple-sub-output {
    width: 100%;
    height: 100%;
    box-sizing: border-box;
    border-radius: 10px;
    padding: 10px;
    background-color: #002b36;
    /* color: #93a1a1; */
    /* color: #cacaca; */
    color: #efefef;
    font-size: 14px;
}
#simple-sub-input {
    resize: none;
    outline: none;
}

#simple-sub-output {
    border: 1px solid black;
}

.binding {
    font-family: monospace;
    white-space: pre;
}

.name::before {
    content: "val ";
    color: #839496;
}

.name::after {
    content: " : ";
    color: #839496;
}

.name, .type {
    display: inline;
}
.name {
    color: #93a1a1;
    font-weight: bold;
}
.type {
    color: #859900;
    font-weight: bold;
    display: inline-block;
}