HTML / CSS: Issues Creating Three Columns - html

Question

I created three columns spread across 90% of the width page width and also centred on the page using "margin: auto". I wanted to have the three columns of equal width with equal spacing in between but was unable to achieve my desired result. How would I ago about doing this?
html, body {
width: 100%;
height: 100%;
margin: 0px;
background-color: #fbe3cf;
}
.ColumnContainer {
height: 100%;
width: 90%;
margin: auto;
}
.c1 {
float: left;
width: 30%;
height: 70%;
background-color: green;
}
.c2 {
float: right;
width: 30%;
height: 70%;
background-color: #DDDDDD;
}
.c3{
float: right;
width: 30%;
height: 70%;
background-color: yellow;
}
<div class="ColumnContainer">
<div class="c1">c1</div>
<div class="c3">c3</div>
<div class="c2">c2</div>
</div>

Answer 1

You can use flex box to easily achieve this, here is the css for the desired result which also keeps it fully responsive.
here is a more detailed explanation on flex box and what you can achieve
html, body {
width: 100%;
height: 100%;
margin: 0px;
background-color: #fbe3cf;
}
.ColumnContainer {
height: 100%;
width: 90%;
margin: auto;
display:flex;
justify-content:space-between;
}
.c1 {
width: 30%;
height: 70%;
background-color: green;
}
.c2 {
width: 30%;
height: 70%;
background-color: #DDDDDD;
}
.c3{
width: 30%;
height: 70%;
background-color: yellow;
}
<div class="ColumnContainer">
<div class="c1">c1</div>
<div class="c3">c3</div>
<div class="c2">c2</div>
</div>

Answer 2

You can remove float and make them as inline-block, and then center the elements present in the ColumnContainer.
html, body {
width: 100%;
height: 100%;
margin: 0px;
background-color: #fbe3cf;
}
.ColumnContainer {
height: 100%;
width: 90%;
margin: auto;
text-align: center;
}
.ColumnContainer > div{
display:inline-block;
width:30%;
}
.c1 {
height: 70%;
background-color: green;
}
.c2 {
height: 70%;
background-color: #DDDDDD;
}
.c3{
height: 70%;
background-color: yellow;
}
<div class="ColumnContainer">
<div class="c1">c1</div>
<div class="c3">c3</div>
<div class="c2">c2</div>
</div>