Is number 1 in correct format? I collect it from MDN.

Question

font-family: Gill Sans Extrabold, sans-serif; font-family: "Goudy Bookletter 1911", sans-serif;

Answer 1

According to MDN the first one is valid. But, w3.org recommends to quote font family names that contain white space, digits, or punctuation characters other than hyphens:

Answer 2

When you're unsure use this

https://jigsaw.w3.org/css-validator/#validate_by_input

Copy and paste this to check validation

p {font-family: Gill Sans Extrabold, sans-serif; font-family: Goudy Bookletter 1911, sans-serif;}

then this

p {font-family: Gill Sans Extrabold, sans-serif; font-family: "Goudy Bookletter 1911", sans-serif;}

Answer 3

Both declarations are valid

"Font family names must either be given quoted as strings, or unquoted as a sequence of one or more identifiers. This means that punctuation characters and digits at the start of each token must be escaped in unquoted font family names." - MDN

Answer 4

These are the guys who make the standards. https://www.w3.org/TR/CSS2/fonts.html

Answer 5

Chris C. Thanks

Answer 6

Chris C. Maybe quated format is more valid, I use this. Validators shows no warning.

Answer 7

Chris C. But why it is invalid?
font-family: Goudy Bookletter 1911, sans-serif;
can you please make some explanation?