body {
    font-family: verdana;
    background-color: orange;
    background-image: url(/images/background_index.jpg); background-size: cover;
}
header, nav, main, article, aside, footer, section, div {
    border: 8px solid green;
    margin: 12px;
    padding: 12px;
    border-radius: 20px;
}

h1 {
    font-size: 36pt;
    color: green;
    text-align: center;
}

header p {
    text-align: center;
}

h2 {
    color: yellowgreen;
}

h3 {
    color: yellowgreen
}
a {
    border: 4px solid red;
    padding: 5px;
    background-color: yellowgreen;
    text-decoration: none;
    border-radius: 15px;
}

a:hover {
    font-style: italic;
    border: 7px solid yellowgreen;
    background-color: red;
}

img {
    float: right;
    height: 250px;
    margin: 6px;
    border: 8px solid green;
    border-radius: 20px;
}

article {
    float: left;
    width: 65%;
}

aside {
    float: right;
    width: 25%;

}
 
 main {
     overflow: hidden;
 }

 li {
     margin-bottom: 25px;
     list-style: square;
 }

 dt {
     margin-top: 16px;
     margin-bottom: 8px;
 }

 section {
     display: flex;
     flex-flow: row wrap;
 }

 .div1 {
     flex: 1 1 30%;
     background-image: url(/images/trees.jpg); background-size: cover;
     min-height: 25vh;
 }

 .div2 {
    flex: 1 1 30%;
    background-image: url(/images/mountain.jpg); background-size: cover;
    min-height: 25vh;
 }