%extension-install-button {
    vertical-align: top;
    margin-right: 10px;
    background-size: 32px 32px;
    display: inline-block;
    height: 50px;
    width: 32px;
    background: no-repeat 0px 9px;
}

.install-chrome {
  @extend %extension-install-button;
  background-image: image-url('browser-icons/Chrome-32x32.png');
}

.install-firefox {
  @extend %extension-install-button;
  background-image: image-url('browser-icons/Firefox-32x32.png');
}

.install-safari {
  @extend %extension-install-button;
  background-image: image-url('browser-icons/Safari-32x32.png');
}

%extension-install-button {
    vertical-align: top;
    margin-right: 10px;
    background-size: 32px 32px;
    display: inline-block;
    height: 50px;
    width: 32px;
    background: no-repeat 0px 9px;
}

.install-chrome {
  @extend %extension-install-button;
  background-image: asset-data-url('browser-icons/Chrome-32x32.png');
}

.install-firefox {
  @extend %extension-install-button;
  background-image: asset-data-url('browser-icons/Firefox-32x32.png');
}

.install-safari {
  @extend %extension-install-button;
  background-image: asset-data-url('browser-icons/Safari-32x32.png');
}

Use asset data URL instead of image url
Use asset data URL instead of image url
