The value px for a width property is incorrect, it should include both the value and the units, like 10px, or just 0 if it’s zero width. Using only the units without the value is incorrect.
Example of Incorrect CSS
Corrected Example of CSS
Make sure to include the unit (like px, em, %, etc.) when specifying the width:
Conclusion
Always ensure to provide proper units when specifying dimensions in CSS. Common units are:
px (pixels)
em (relative to the font size of the element)
% (percentage of the parent element’s width)