styles.css

h1 {
    text-align: center;
}

#inputLine, #outputWrap, #labelLine, #blockInput {
    display: block;
    margin: 0 auto;
    width: 60%;
}

#page {
    width: 80%;
    margin-left: auto;
    margin-right: auto;
    border: 1px solid black;
}

p, ol, ul {
    font-family: Helvetica, Arial, sans-serif;
    margin-left: auto;
    margin-right: auto;
    width: 90%;
}

#inputLine {
    margin-bottom: 10px;
}

#input {
    width: 80%;
}

#eval {
    width: 15%;
}

#labelLine label {
    float: left;
    width: 50%;
    text-align: left;
}

#labelLine a {
    width: 50%;
    float: left;
    text-align: right;
}

#blockInput {
    clear: both;
}

#blockInput textarea {
    display: block;
    height: 300px;
    width: 100%;
}

#blockInput button {
    display: block;
    margin-left: auto;
    margin-right: auto;
}

#outputWrap {
    clear: both;
    border: 1px solid black;
    width: 60%;
    height: 80px;
    padding: 0;
}

#output {
    overflow-y: auto;
    width: 99.5%;
    height: 100%;
    margin: 0;
    padding: 0;
}

.inputText, .outputText, .errorText {
    width: 100%;
}

.inputText {
    color: black;
}

.outputText {
    color: green;
}

.errorText {
    color: red;
}