I am new to HTML, CSS I am trying to create a website for my project however one of the requirements is it should be the responsive website. for some reason, my yellow box becomes smaller and smaller unlike my red and blue box which are big when I clicked smartphone to view, laptop view and different another view it just the yellow box became small and thin. I wanted o to ask for help or advice to make it a responsive website thank you
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" rel="stylesheet"/>
<div class="row">
<div class="col-md-4" style="margin-left: 3%" >
<div class="color">Column 1</div>
<div class="color" >Column 2</div>
</div>
<div class="col-md-8">Column 3</div>
</div>
<style type="text/css">
.color:nth-child(1) {
background:red;
height:40%;
margin-top:5%;
margin-left: 2%;
border-radius: 4%;
width: 100%;
}
.color:nth-child(2) {
margin-top: 3%;
border-radius: 4%;
background:blue; height:260px;
}
.col-md-8 {
background:yellow; height:628px;
width: 38%;
margin-left: 15%;
margin-top: 1%;
border-radius: 9%;
}
</style>