Why default button overrides outline on focus event? - html

Question

I do not know if it is a bug or not, but it seems to be.
When you have a default button and you click it when you have a :focus pseudo class it does not seem to have an outline.
#buttontag:focus {
}
<button id="buttontag" type="button">Focus me</button>
It shows the outline when you use tab key, though.
Nevertheless, it shows the outline both when clicking or using tab key on the button if you change the background-color to it.
#buttontag:focus {
background-color: #dde;
}
<button id="buttontag" type="button">Focus me</button>
But it does not work for all types of background-color. For example, it does not work for background-color: #ddd. In this case it is only shows when you use tab key.
#buttontag:focus {
background-color: #ddd;
}
<button id="buttontag" type="button">Focus me</button>
Here an screenshot when the button is focused, nothing changes.
I know that the background-color: #ddd is the same colour as the default border of the button (both on focus or not focused). I have created the following code to be sure of it.
var buttontag = document.getElementById('buttontag');
buttontag.onfocus = function(){
var border = window.getComputedStyle(buttontag).getPropertyValue("border");
alert(border);
}
var border = window.getComputedStyle(buttontag).getPropertyValue("border");
alert(border);
#buttontag:focus {
background-color: #ddd;
}
<button id="buttontag" type="button">Focus me</button>
I know that rgb(221, 221, 221) is the same as #DDDDDD on hex and that is the same as #ddd. I do not know if it has to be something related about contrast between both colours (there is no contrast because they are the same colour) and outline but it is very strange that in this background-color the outline does not appear.
More and more strange
If you inspect the default button and you force it to be focussed (I am trying on Google Chrome debugger) , it has an outline and shows it on the button. It is the default outline that appears in the rest of buttons with another background-color.
:focus {
outline: -webkit-focus-ring-color auto 5px;
}
And I also wanted to know if it was something related about forcing the button to be in focus state so I created a Javascript snippet to see what outline the button has in focus state.
var buttonFocus = document.getElementById('buttontag');
buttonFocus.onfocus = function(){
var outline = window.getComputedStyle(buttonFocus).getPropertyValue("outline");
alert(outline);
}
#buttontag:focus {
background-color: #ddd;
}
<button id="buttontag" type="button">Focus me</button>
It retrieves the default outline, but does not show it. It seems that it only shows the outline if you force the button to be focussed (on the debugger).
I have searched on the official documentation but could not find anything related about a special behaviour for default buttons or specific background-color.
So here I have some questions:
Why is the outline not displayed on the default button when you click on it?
Why with background: #ddd it is not shown also?
Why is the outline shown when you use tab and not when you click on the button (on the two cases above)?
Why the button has the outline in his CSS but it does not display it? Is it a bug?

Answer 1

Might be wrong.
The default button (in Google Chrome at least) uses appearance
style attribute:
button {
-webkit-appearance: button;
}
The appearance property allows you to make elements look like a
standard user interface element from your operating system. Talking about OS X, standard interface buttons do not have outline
by default.
Very easy way to check how the standard os buttons looks:
alert('I am standard button')
When you've created a button:focus pseudo-class that contained
background or border rule (example #2), you have overridden the
standard appearance by default browser style for button + your
rules.
In example #1, the button:focus is empty, and apparently it is
just ignored by the browser, hence os interface style is applied.
If you will create a style:
button { -webkit-appearance: initial; }
you will get default browser button that has outline.
Chrome's default style for button has a rule:
background-color: buttonface;
Safari and Google Chrome support custom color names that are
references to the currently used colors of user interface elements.
It might be the case, that buttonface is '#dddddd' in your system. Interesting though, as I can see the blue outline in OS X Chrome.
For the questions 3 and 4, I am afraid I cannot replicate it, as I do get outline.
Will update the answer after some research. Cheers! :)

Answer 2

webkit Chrome and Safari behave differently, in that they do not trigger :focus on a click event, but do on tab keyboard event.
That :focus behavior is present, especially on the button element.
So you might have to add tabindex attribute on your button element to let the browser know that this element can receive focus.
tabindex="0"
Since without that tabindex attribute, the browser sees that focus flag as being false, hence no :focus.
See W3C spec:
https://drafts.csswg.org/selectors-3/#the-user-action-pseudo-classes-hover-act
There may be document language or implementation specific limits on which elements can become :active or acquire :focus.
Also see the following regarding focused browsing context
https://html.spec.whatwg.org/multipage/interaction.html#currently-focused-area-of-a-top-level-browsing-context
If the attribute is omitted or parsing the value returns an error.
The user agent should follow platform conventions to determine if the element's tabindex focus flag is set and, if so, whether the element and any focusable areas that have the element as their DOM anchor can be reached using sequential focus navigation, and if so, what their relative position in the sequential focus navigation order is to be.
Modulo platform conventions, it is suggested that for the following elements, the tabindex focus flag be set:
a elements that have an href attribute
link elements that have an href attribute
button elements
You can also see this related StackOverflow question:
css focus not working in safari and chrome

Answer 3

button has a default style define by each browser. it might (and often is) different from browser to browser. But we can overwrite the default values to suit our needs.
Why is the outline not displayed on the default button when you click on it?
The button doesn't enter in focus state when you click. It enters the active state.
Why with background: #ddd it is not shown also?
It does show in my browser, but only when in focus. I your examples you use #ddd and #dde which are 2 very similar grays to the default gray, but once I changed the value I could see the difference.
Why is the outline shown when you use tab and not when you click on the button (on the two cases above)?
The focus state is meant to allow the user to hit the Enter/Return key to activate the button. However, the button doesn't enter the focus state one it is clicked
Why the button has the outline in his CSS but it does not display it? Is it a bug?
It is not a bug. It only displays when in focus state, which can be forced through the code inspector, via javascript or by tabbing through form elements. I used my own example declaring:
outline: 2px solid #ccc;
The focus state is very useful when trying t make the application/website accessible to screen readers for people who are visually impaired. It allows us to add more functions that can be triggered in those situations, and to guide the user through the page when looking at it isn't possible.

Answer 4

The default browser behavior is to show an outline only on focus (by using tab f.e.), not on click. Each browser also may have it's default outline color and width.
To avoid any funny behavior you can overwrite the outline, and also add it to a click:
#buttontag:focus, #buttontag:active {
outline: #ddd solid 2px;
}