If frameborder is obsolete, why does youtube still use it?

[asasass]

If frameborder is obsolete, why does youtube still use it?

[ronpat]

You would have to ask YouTube why they have not replaced frameborder with a CSS equivalent.

[asasass]

I read putting [border 0;] in style is the replacement for that.

[ronpat]

Yes, it is.
(don’t forget the colon)

[asasass]

it’s there.

[asasass]

@asasass

border 0;

you mean, semicolon

[ronpat]

No, I meant the colon between the word “border” and the zero.

[asasass]

style="border: 0;"

[asasass]

If you already have a border, [border: 5px solid #5CB378;] adding an additional border: 0; would probably have no effect, right?

[ronpat]

@asasass

f you already have a border, [border: 5px solid #5CB378;] adding an additional border: 0; would probably have no effect, right?

It depends on where those border assignments fall in CSS. The C stands for Cascading so assuming the same specificity the last border assignment is the one that is applied. In inline styles, the properties are read from left to right. The rightmost would win.