Welcome to the Treehouse Community
Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.
Looking to learn something new?
Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.
Start your free trial2 Answers
Naomi Freeman
Treehouse Guest TeacherThis has to do with mobile.
So width you're saying "always be 40% of the window"
But max-width is saying "you can be a maximum of 100% of the window ever (if it's a tiny device)" or "you can be a max of 1300px" for a big imac, if you know that it's going to break and look bad.
The max-width property is used to set the maximum width of a given element. It prevents the used value of the width property from becoming larger than the value specified for max-width.
Stone Preston
42,016 Pointssee this forum post for a detailed explanation of the difference between width and max-width