"width: calc(100% / 3);" not working properly

Question

I have a 3 column layout that should fill the whole screen so on my columns I am using:

width: calc(100% / 3);

So lets say for example my screen is 782px wide:

782 / 3 = 260.66̅

However the problem I have is in Internet Explorer, where it rounds the pixels to two decimal places (260.67)

260.67 * 3 = 782.01

So at certain widths, I lose a 1/3 of my page as it wraps underneath.

Here's an example:

function onResize() {
    $('ul').each(function() {
        var H = eval($(this).height() / $(this).children('li').length);
        $(this).children('li').outerHeight(H);
        $(this).children('li').css('line-height', H + 'px');
        $(this).children('li').outerWidth($(this).width());
    });
}

var timer;
$(window).resize( function() {
    timer && clearTimeout(timer);
    timer = setTimeout(onResize, 100);
});
onResize();

html {
    height:100%;
}
body {
    background:black;
    margin:0;
    padding:0;
    overflow:hidden;
    height:100%;
}
ul {
    width: calc(100% / 3);
    display: inline-block;
    overflow:hidden;
    margin:0;
    padding:0;
    float:left;
    height:100%;
    list-style: outside none none;
}
ul li {
    background: rgb(230,240,163);
    background: -webkit-gradient(linear, 0 0, 0 100%, from(rgba(230,240,163,1)), color-stop(0.5, rgba(210,230,56,1)), color-stop(0.51, rgba(195,216,37,1)), to(rgba(219,240,67,1)));
    background: -webkit-linear-gradient(rgba(230,240,163,1) 0%, rgba(210,230,56,1) 50%, rgba(195,216,37,1) 51%, rgba(219,240,67,1) 100%);
    background: -moz-linear-gradient(rgba(230,240,163,1) 0%, rgba(210,230,56,1) 50%, rgba(195,216,37,1) 51%, rgba(219,240,67,1) 100%);
    background: -o-linear-gradient(rgba(230,240,163,1) 0%, rgba(210,230,56,1) 50%, rgba(195,216,37,1) 51%, rgba(219,240,67,1) 100%);
    background: linear-gradient(rgba(230,240,163,1) 0%, rgba(210,230,56,1) 50%, rgba(195,216,37,1) 51%, rgba(219,240,67,1) 100%);
    filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#e6f0a3', endColorstr='#dbf043',GradientType=0 );
    text-align:center;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul id="ul1">
    <li>Test 1</li>
    <li>Test 2</li>
</ul>
<ul id="ul2">
    <li>Test 3</li>
    <li>Test 4</li>
</ul>
<ul id="ul3">
    <li>Test 5</li>
    <li>Test 6</li>
</ul>

Does anyone know of an elegant way of solving this problem?

I know I could use width: 33.33%, however there's a small part of me inside that cries knowing that it's not 100% bang on.

Answer 1

Try width: calc(100% * 0.33333); to make sure float rounding errors err on the side of caution or width: calc((100% / 3) - 0.1px);.

Answer 2

2020 Answer

Use flexbox:

.container {
   width: 242px; /* /3 = 80.66̅  */
   height: 100px;
   
   display: flex;
}

.col {
  flex: 1 0 0; /* Set flex basis to 0 to force equal widths */
}

.col1 {
  background-color: red;
}
.col2 {
  background-color: green;
}
.col3 {
  background-color: blue;
}

<div class="container">
  <div class="col col1"></div>
  <div class="col col2"></div>
  <div class="col col3"></div>
<div>

Old Answer

It would seem that the suggestion by @web-tiki with:

width:33.33%;

is the best option.