body {
    background-color: #f5f5f5;
    color: #333;
}

h1 {
    font-size: 2em;
    font-weight: normal;
    margin: 0.67em 0;
    color: black;
    font-weight: bold;
}

#application {
    width: 100%;
    height: 100%;
    background-color: #f0f0f0;
    position: relative;
    overflow: hidden;
    text-align: center;
}

#form {
    background-color: #afa;
    font-size: 1.5em;
}

#expression {
    background-color: #f0f0f0;
    border: 1px solid #000;
    padding: 0.5em;
    font-weight: bold;
    color: #000;
}

#expression:focus {
    background-color: #fff;
    border: 1px solid #123;
    color: #123;
}

#expression:invalid {
    background-color: #f00;
    border: 1px solid #000;
    color: #000;
}

#calc {
    background-color: #f0f0f0;
    border: 1px solid #000;
    padding: 0.5em;
    font-weight: bold;
    color: #000;
}

#calc:hover {
    background-color: #fff;
    border: 1px solid #123;
    color: #123;
}

#reset {
    background-color: #0f0f0f;
    border: 1px solid #fff;
    padding: 0.5em;
    font-weight: bold;
    color: #fff;
}

#reset:hover {
    background-color: #fff;
    border: 1px solid #123;
    color: #123;
}

#result {
    background-color: #f0f0f0;
    border: 1px solid #000;
    padding: 0.5em;
    font-weight: bold;
    color: #000;
}