I need a fixed position element into the floated element, I tried below snippet codes but it doesn't work, it makes fixed box width 100% based to device width, but i need it to be 100% width floated ".left-column" box
.left-column, .right-column {
width: 20%;
box-sizing: border-box;
float: right;
position: relative;
display:inline-block;
background: blue;
direction: rtl;
height:1000px;
}
.right-column {
width: 80%;
background:#b54930
}
.fixed-inner-box{
width: 100%;
border:1px solid black;
height:100px;
box-sizing:border-box;
z-index:5;
background:red;
position:fixed
}
<div class="left-column">
<div class="fixed-inner-box">
</div>
</div>
<div class="right-column">
</div>