html - div with same margin top and bottom (no %) -

all want have small black line on left of screen borders top , bottom 30px.

it's pretty if use % won't have 30 px on top , bottom.

#border-right {     right:0;      width: 71px;      height: 94%;      top: 3%;      bottom: 3%;      position:fixed;      background:rgba(255,255,255,.9);     border-left:2px solid black;     z-index:1; } 

here's i'm stuck — https://jsfiddle.net/9o3t5u2d/

thanks! f.

you can set top , bottom offsets 30px, no math required.

i not sure why need width , background color, can add needed.

#border-right {    position: fixed;    z-index: 1;    right: 0;    top: 30px;    bottom: 30px;    box-sizing: border-box;    border-right: 2px solid black;    width: 30px; /* not sure if need this... */    background: rgba(125, 125, 125, .5); /* not sure if need this... */  }

<div id="border-right"></div>