outline
Borders
A line drawn outside the border; it takes no space, which is why focus rings use it.
| How to write it | outline: none; |
|---|---|
| Common values | none, 2px solid #0ea5e9 |
| Inherited | No — it stops at this element |
| Sets all of | outline-width, outline-style, outline-color |
| Category | Borders |
How to read this
- An inherited property only needs writing once on the parent — every child picks it up. Most text properties work this way.
- A shorthand resets whatever you leave out. Writing background: red alone also wipes a background image you set earlier.
- When rules collide, the more specific selector wins; only when specificity ties does source order decide.
- Animate transform and opacity for smoothness. Changing width or top forces the layout to be recalculated.
Frequently asked questions
Q. What is the CSS outline property?
A line drawn outside the border; it takes no space, which is why focus rings use it.
Q. How do you write outline?
As outline: none; Common values include none, 2px solid #0ea5e9.
Q. Is outline inherited?
No. It applies only where you write it, so each element needs its own declaration.
Q. What does the outline shorthand set?
outline-width, outline-style, outline-color — and anything you leave out resets to its default.