That is a default behaviour of each browser; your browser seems to be Safari, in Google Chrome it is orange in color!
Use this to remove this effect:
button {
outline: none; // this one
}
More Related Contents:
- What is the difference between visibility:hidden and display:none?
- What does the “+” (plus sign) CSS selector mean?
- What is the difference between Normalize.css and Reset CSS?
- CSS \9 in width property
- Opacity CSS not working in IE8
- CSS hover border makes inline elements adjust slightly
- What is the meaning of “cascading’ in CSS?
- Justify the last line of a div?
- Difference between @import and link in CSS
- Angular-cli from css to scss
- Position a CSS background image x pixels from the right?
- Style certain characters with CSS
- What is the difference between :focus and :active?
- Why does ‘overflow: auto’ clear floats? And why are clear floats needed?
- Bootstrap grid with fixed wrapper – Prevent columns from stacking up
- font-size vs line-height vs actual height
- Bootstrap 4 – Navbar items outside the collapse
- hide div tag on mobile view only?
- Allowed characters for CSS identifiers
- How to use relative/absolute paths in css URLs?
- Zebra striping a table with hidden rows using CSS3?
- Which are the most important media queries to use in creating mobile responsive design?
- Less lists as a mixin argument(s)
- What is the difference between `margin` and `padding` in CSS?
- How to show the first N elements of a block and hide the others in css?
- Width equal to content [duplicate]
- Align form elements in CSS
- How can I align 3 divs side by side?
- How to override the properties of a CSS class to avoid copying and renaming styles
- text overflow ellipsis: avoid word break