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              <h1>One Pixel is not always one pixel</h1>
  <h2>Or: Browsers are really bad at rounding and here is why</h2>

  <p class="expl">All of the paragraphs in the gray box are set with a font size of .875em equaling 14 pixels in relation to the font size of the body (which is 16 pixels in all modern browsers). <b>Right? Right!</b></p>

  <section class="test">

    <h3>Test Case</h3>

    <p class="now-u-dont">Laaaaaaalaaalalaaaaaa</p>

    <p class="now-u-sea-me">Trolololololololooooo</p>

    <p class="invisible-border">hahahahahaaaahahahahahaaaa</p>

  </section>

  <p class="expl">The first paragraph in the box has a value of .0625em for the attribute border-bottom. .875em divided by .0625em equals .0546875. With this in mind one should expect browsers to render a one-pixel line after this value is rounded. <b>Right? Wrong!</b></p>

  <p class="expl"><em>Firefox</em> is rendering a one pixel border, all cool, but <em>Chrome</em> is not and <em>Safari</em> as well is not doing its job. <em>Opera</em>, since it moved to Webkit, is also not displaying the border for the first paragraph.</p>

  <p class="expl">By the way: the second paragraph has a border-width of .07071428572em which is the minimum value where webkit is rendering the one pixel border. One could go on adding numbers after the dot but let's not get too carried away here. Oh, and in case you wondered: 1 divided by 14 equals .<span class="period">0714285</span>. <b>Right? Right!</b></p>

  <p class="expl">So after seeing this test we can all agree, that Firefox is doing a good job at rounding and that Webkit should go visit some basic math courses. <b>Right? Wrong!</b></p>

  <p class="expl">The last paragraph features the lowest value where Firefox is still rendering a one pixel border, which is (brace yourselves): .0006em ?!? A true WTF moment because I can't see the relation.</p>

  <h4>Conclusion</h4>

  <p>Browsers are bad at rounding no matter what and I don't understand the decisions behind the values where a pixel is rendered or not. It really makes me wonder how bad this can get regarding design decisions.</p>
            
          
!
            
              body {
  font-size: 100%;
  font-family: "Helvetica Neue", Segoe, Roboto, "Droid Sans", sans-serif;
  line-height: 1.46em;
  margin: 0 auto;
  padding: 2em;
  width: 40em;
  color: #766576;
}
h2 {
  margin-bottom: 1.4em;
}
h4 {
  font-size: 1.25em;
  text-transform: uppercase;
  margin: 2em 0 .6em;
}
p {
  font-size: 1.25em;
  line-height: 1.55em;
}
img {
  float: right;
}
.test {
  padding: .5em 1em 1em;
  margin: 1.5em 0;
  background: #e5e5e5;
  border: .0625em solid #f93;
}
.now-u-dont,
.now-u-sea-me,
.invisible-border {
  font-size: .875em;
}
.now-u-sea-me {
  border-bottom: .07071428572em solid #69f;
}
.now-u-dont {
  border-bottom: .0625em solid #69f;
}
.invisible-border {
  border-bottom: .0006em solid #69f;
}
.period {
  text-decoration: overline;
}
            
          
!
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