* {
    margin: 0 auto;
    padding: 0;
}

.header {
    width: 100%;
    height: 100px;
    background-color: #f5f5f5;
    border-bottom: 1px solid #e5e5e5;
}

.aside {
    height: 100%;
    width: 12rem;
    position: absolute;
    left: 0;
    top: 100px;
    padding-top: 40px;
}

.aside h3 {
    text-align: center;
}

.aside ul {
    list-style: square;
    margin-left: 1.5rem;
}

.container {
    margin-left: 12rem;
    height: 100%;
}

.container p {
    text-align: justify;
    margin-top: 1rem;
    margin-bottom: 1rem;
    margin-right: 1rem;
}

.container ul {
    margin-left: 2rem;
    margin-top: 1rem;
    text-align: justify;
    list-style: upper-roman;
}

.container ul li {
    margin-bottom: 0.5rem;
}


.title-1 {
    text-align: center;
}

.resources {
    display: inline-block;
    margin-top: 1rem;
    width: 100%;
}

.resources a {
    text-decoration: none;
    list-style: none;
    color: #000;
}

.resources img {
    width: 100px;
    height: 75px;
}

.logo-source-download {
    vertical-align: middle;
}

.resources b {
    vertical-align: middle;
    margin-left: 0.5rem;
    margin-right: 0.5rem;
}

.nav {
    margin-top: 1rem;
    margin-bottom: 1rem;
    margin-left: 10rem;
    height: 50px;
}

.nav .next {
    float: right;
    margin-right: 8rem;
    background-color: #199319;
    color: white;
    padding: 15px 25px;
    text-decoration: none;
    border-radius: 25px;
}

.nav .next:hover {
    background-color: #145314;
}

.nav .preview {
    float: left;
    margin-left: 1rem;
    background-color: #199319;
    color: white;
    padding: 15px 25px;
    text-decoration: none;
    border-radius: 25px;
}

.nav .preview:hover {
    background-color: #145314;
}

.image-center{
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
    text-align: center;
    margin-bottom: 2rem;
}

.image-center img{
    width: 500px;
    height: auto;
}

.code{
    padding: 1rem;
    display: inline-block;
    text-align: center;
    font-size: larger;
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    border: #000 dotted 1px;
}

.code .yellow{
    color: #d3b615;
}

.code .blue{
    color: #0066ff;
}

.code .green{
    color: #009900;
}

.code .orange{
    color: #ff9900;
}

.homework{
    margin-top: 1rem;
    margin-bottom: 3rem;
    margin-left: 10rem;
}