JSFiddle - React, Tailwind, and code Playground

HTML

<div id = "wrapper">
 <div class = "leftMenu"></div>
 <div class = "rightBlock block1"></div>
 <div class = "rightBlock block2"></div>
 <div class = "rightBlock block1"></div>
 <div class = "rightBlock block2"></div>
 <div class = "rightBlock block1"></div>
</div>

CSS

.leftMenu {
    width: 100px;
    height: 300px;
    background: green;
    float: left;
}
#wrapper :last-child:after {
    clear: both;
}
.block1 {
    background-color: red;
    width: 400px;
    height: 50px;
}
.block2 {
    background-color: blue;
    width: 400px;
    height: 100px;
}