css divide width 100% to 3 column

I have a layout where I have 3 columns.

Therefore, I divide 100% by 3.

The result is obviously 33.333....

My goal is perfect 1/3 of screen.

Question:

How many numbers after dot can CSS handle to specify 1/3 of width ?

e.g. 33.33333 (n=5) ← how many n can css handle

HTML:

<div id="wrapper">
    <div id="c1"></div>
    <div id="c2"></div>
    <div id="c3"></div>
</div>

CSS:

#c1, #c2, #c3 {
    width: 33%; // 1/3 of 100%
}

Is there a better way to divide by 3?

Solution 1:

As it's 2018, use flexbox - no more inline-block whitespace issues:

body {
  margin: 0;
}

#wrapper {
  display: flex;
  height: 200px;
}

#wrapper > div {
  flex-grow: 1;
}

#wrapper > div:first-of-type { background-color: red }
#wrapper > div:nth-of-type(2) { background-color: blue }
#wrapper > div:nth-of-type(3) { background-color: green }

<div id="wrapper">
  <div id="c1"></div>
  <div id="c2"></div>
  <div id="c3"></div>
</div>

Or even CSS grid if you are creating a grid.

body {
  margin: 0;
}

#wrapper {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-auto-rows: minmax(200px, auto);
}

#wrapper>div:first-of-type { background-color: red }
#wrapper>div:nth-of-type(2) { background-color: blue }
#wrapper>div:nth-of-type(3) { background-color: green }

<div id="wrapper">
  <div id="c1"></div>
  <div id="c2"></div>
  <div id="c3"></div>
</div>

Use CSS calc():

body {
  margin: 0;
}

div {
  height: 200px;
  width: 33.33%; /* as @passatgt mentioned in the comment, for the older browsers fallback */
  width: calc(100% / 3);
  display: inline-block;
}

div:first-of-type { background-color: red }
div:nth-of-type(2) { background-color: blue }
div:nth-of-type(3) { background-color: green }

<div></div><div></div><div></div>

JSFiddle

References:

How to remove the space between inline-block elements?
MDN calc()
Can I Use calc()

Solution 2:

A perfect 1/3 cannot exist in CSS with full cross browser support (anything below IE9). I personally would do: (It's not the perfect solution, but it's about as good as you'll get for all browsers)

#c1, #c2 {
    width: 33%;
}

#c3 {
    width: auto;
}