body {
    margin: 0;
    padding-top: 80px;
    background-color: white;
    font-family: Arial, sans-serif;
}
#header-bar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 80px;
    background-color: blue;
    color: white;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    font-weight: bold;
    z-index: 1000;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

a {
    text-decoration: none;
    outline: none;
    color: white;
}
    .container{
    width: 600px;
    height: 600px;
    background-color: red;
    border: 6px solid black;
    margin: 150px auto;
}
.div1{width: 150px;
    height: 150px;
    background-color: blue;
    border-bottom: 6px solid black;
    border-right: 6px solid black;
    box-sizing: border-box;
    float: left;
}
.div2{width: 150px;
    height: 300px;
    background-color: green;
    box-sizing: border-box;
    float: right;
    border-left: solid black 6px;
}
.div3{width: 300px;
height: 150px;
background-color: yellow;
    border-bottom: solid black 6px;
box-sizing: border-box;
    float: left;
}
.div4 {
    float: right;
    width: 200px;
    height: 150px;
    background-color: white;
    border-left: solid black 6px;
    box-sizing: border-box;
}
.div5 {
    clear: both;
    float: left;
    width: 150px;
    height: 150px;
    background-color: olivedrab;
    box-sizing: border-box;
    border-top: solid black 6px;
    border-right: solid black 6px;
}
.div6 {
    float: left;
    width: 200px;
    height: 150px;
    background-color: rebeccapurple;
    box-sizing: border-box;
    border-top: solid black 6px;
}
.div7 {
    float: left;
    width: 250px;
    height: 150px;
    background-color: aqua;
    box-sizing: border-box;
    border-top: solid black 6px;
    border-left: solid black 6px;
}
.div8 {
    clear: left;
    float: left;
    width: 250px;
    height: 150px;
    background-color: yellow;
    box-sizing: border-box;
    border-right: solid black 6px;
    border-top: solid black 6px;
}

.div9 {
    float: left;
    width: 200px;
    height: 150px;
    background-color: maroon;
    box-sizing: border-box;
    border-top: solid black 6px;
}

.div10 {
    float: left;
    width: 150px;
    height: 150px;
    background-color: #A3C893; /* groen accent */
    box-sizing: border-box;
    border-left: solid black 6px;
    border-top: solid black 6px;
}