vertical lines with full height between divs

Question

I have three divs (left, mid and right) and these divs don't have an exact height, because it depends on how many rows text are inside the div. Now I want vertical lines (which seperate the three divs) through the whole height of the users monitor, no matter how high the divs are.

How can I do this? Because , as you can see in the css-code, border-right/border-left don't work for me.

Intention HTML

<div class="content">
    <div class="content_left"></div>
    <div class="content_mid"></div>
    <div class="content_right"></div>
</div>

CSS

.content {  
    line-height: 1.1;
    background-color: #FFF;
    color: #000; 
    position: absolute;
    top: 36px; /* because there is a top-menu which is 36px high */
    left: 70px; /* because there is a side-menu which is 70px wide */
    right: 0px;
    bottom: 0px;
    overflow-x: hidden;
    overflow-y: auto;
}
.content_left {
    position: absolute;
    width: 22.5%;
    left: 0px;
    top: 0px;
    border-right: 1px solid #ccc;
    padding: 10px;
    overflow-x: hidden;
    overflow-y:hidden;
}
.content_mid {
    position: relative;
    width: 50%;
    top: 10px;
    left: 25%;
    float: left;
    padding-left: 10px;
}
.content_right {
    position: absolute;
    width: 22.5%;
    right: 0px;
    top: 0px;
    border-left: 1px solid #ccc;
    padding: 10px;
    overflow-x: hidden;
    overflow-y: hidden;
}

Edit 1: I would like to have these seperate-lines 1px wide and I cannot set the height of content_left, content_mid, content_right to 100% because I have resizeable boxes in these divs.

Answer 1

I think this does what you want.

JSFiddle example

The HTML structure is a bit more complicated than yours:

<div class="menu-top">Menu top</div>
<div class="wrapper">
    <div class="menu-left">Menu left</div>
    <div class="content">
        <div class="column">
            <div class="column-content">
                 <h1>Column 1</h1>
            </div>
        </div>
        <div class="column">
            <div class="column-content">
                 <h1>Column 2</h1>
            </div>
        </div>
        <div class="column">
            <div class="column-content">
                <h1>Column 3</h1>
            </div>
        </div>
    </div>
</div>

And here's the CSS:

body {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    height: 100%;
    width: 100%;
}
.menu-top {
    width: 100%;
    height: 36px;
    background-color: #3498DB;
}
.wrapper {
    display: flex;
}
.menu-left {
    height: calc(100vh - 36px);
    width: 70px;
    background-color: #59ABE3;
}
.content {
    width: calc(100vw - 70px);
    height: calc(100vh - 36px);
    background-color: #E4F1FE;
    display: flex;
}
.column {
    flex: 33;
    border-left: 1px solid hotpink;
}
.column:first-of-type {
    border-left: none;
}