Transform Scale Causing Gaps/Lines - css

Question

I'm building a website currently and am experiencing issues with transform: scale. I've got a button, and when a user hovers over it, two things happen:
A background "sweeps" in diagonally
The button label colour changes
The button grows slightly
I have got this working, and it looks really nice, but after implementing point 3, I'm seeing a weird gap to the left hand side when the button grows.
Here is my code: click for demo
HTML
Hover
CSS
body {
text-align: center;
padding-top: 10%;
}
.button {
display: inline-block;
text-transform: uppercase;
font-size: 1.1em;
font-weight: 600;
background: transparent;
transition: all ease .25s;
border: 3px solid green;
color: green;
position: relative;
overflow: hidden;
z-index: 2;
font-family: sans-serif;
padding: 20px 35px;
text-decoration: none;
}
.button:before {
content: ' ';
transition: all ease-out .25s;
width: 200%;
height: 100%;
position: absolute;
top: 0;
left: 0;
transform-origin: 0 0;
z-index: -1;
transform: skewX(-45deg) translateX(-100%);
background: green;
}
.button:hover:before {
transform: translateX(0);
}
.button:hover {
color: white;
transform: scale(1.1);
}
And here's a screenshot of the gap I'm seeing. This issue occurs in Chrome and Safari (I haven't tested Firefox or IE as I can't download them at work).
Screenshot of weird gap

Answer 1

It "only" appears in Chrome but not Firefox (edit: worse in Edge: first it's on the left then on bottom...). Not sure if a rounding error or something else is the cause of that gap, but I find that replacing border by a box-shadow improves the rendering.
There's still a gap that can be seen near the end of the transition but finally disappears so I added 2 box-shadows on :hover: the new one is inset and fills the gap between "border/box-shadow" and content box faster.
Codepen: http://codepen.io/PhilippeVay/pen/oYjZzK?editors=0100
body {
text-align: center;
padding-top: 10%;
}
.button {
display: inline-block;
text-transform: uppercase;
font-size: 1.1em;
font-weight: 600;
background: transparent;
transition: all ease .25s;
box-shadow: 0 0 0 3px green; /* replaces border which caused a gap in Chr, not Fx */
color: green;
position: relative;
overflow: hidden;
z-index: 2;
font-family: sans-serif;
padding: 19px 34px;
text-decoration: none;
}
.button:before {
content: ' ';
transition: transform ease-out .25s;
width: 200%;
height: 100%;
position: absolute;
top: 0;
left: 0;
transform-origin: 0 0;
z-index: -1;
transform: skewX(-45deg) translateX(-100%);
background: green;
}
.button:hover:before {
transform: translateX(0);
}
.button:hover {
color: white;
box-shadow: 0 0 0 3px green, inset 0 0 0 1px green; /* improves end of transition in Chrome */
transform: scale(1.1);
}
Hover
EDIT: playing with the size of the transitioned :pseudo
.button:before {
content: ' ';
transition: all ease-out .25s;
width: calc(200% + 6px);
height: calc(100% + 6px);
position: absolute;
top: -3px;
left: -3px;
transform-origin: 0 3px;
z-index: -1;
transform: skewX(-45deg) translateX(-100%);
background: green;
}
to take into account the border but that doesn't change anything because of overflow: hidden.
So here's my third try: by adding a container (or having the A element as a container) and keeping the border on the child element, it makes that gap disappear (overflow is around the border).
Codepen: http://codepen.io/PhilippeVay/pen/ZBbKWd
body {
text-align: center;
padding-top: 10%;
}
a {
display: inline-block;
overflow: hidden;
background: transparent;
transition: all ease .25s;
color: green;
position: relative;
z-index: 2;
font-family: sans-serif;
text-decoration: none;
}
a > span {
display: inline-block;
text-transform: uppercase;
font-size: 1.1em;
font-weight: 600;
border: 3px solid green;
padding: 20px 35px;
}
a:before {
content: ' ';
transition: all ease-out .25s;
width: 200%;
height: 100%;
position: absolute;
top: 0;
left: 0;
transform-origin: 0 0;
z-index: -1;
transform: skewX(-45deg) translateX(-100%);
background: green;
}
a:hover:before {
transform: translateX(0);
}
a:hover {
color: white;
transform: scale(1.1);
}
<span class="bd">Hover</span>
Fx transitions till the end flawlessly... and "corrects" the width by adding 2px on the right. But it's already visible in your jsbin so it's another story (and less annoying I guess as user will have clicked by then imho)