author B2G Bumper Bot <>
Wed, 26 Nov 2014 04:41:58 -0800
changeset 242028 3098b45e9a24dc42213a0240d82620dfada6193b
parent 83129 85358854403fbd5c6b1731e2eda2722deea51d98
permissions -rw-r--r--
Bumping manifests a=b2g-bump

<!DOCTYPE html>
    Turns out that the antialiasing on the outer edge of a block with
    border-radius is not consistent if the width and border-width are changed
    even if the resulting shape should look the same.  So clip out the part
    that's too far from the center
  div.outer {
    width: 100px;
    height: 100px;
    overflow: hidden;
  /* We want the following constraints to be satisfied:
     1)  Entire inner div content area is contained inside the 100px square.
     2)  Entire 100px square is contained inside the outer circle of the inner
         div's border.

     This requires that the inner div width/height be < 100px and that the
     radius of the outer circle be at least 50 * sqrt(2).  Let's go with a 75px
     radius for that outer circle.  We then need to shift our inner div up and
     to the left by 25px to center it in the clipping region.

  div.inner {
    width: 50px;
    height: 50px;
    border: 50px solid black;
    background: black;
    border-radius: 100px;
    position: relative;
    top: -25px;
    left: -25px;
<div class="outer"><div class="inner"></div></div>