width
Box and spacing
The horizontal size; 100% follows the parent, 100vw follows the viewport.
| How to write it | width: auto; |
|---|---|
| Common values | auto, 100%, 320px, fit-content |
| Inherited | No — it stops at this element |
| Category | Box and spacing |
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 width property?
The horizontal size; 100% follows the parent, 100vw follows the viewport.
Q. How do you write width?
As width: auto; Common values include auto, 100%, 320px, fit-content.
Q. Is width inherited?
No. It applies only where you write it, so each element needs its own declaration.
Q. What group does width belong to?
The box and spacing group.