fix(css): Update rgb hsl values as per the latest syntax

[dipikabh]

Updates the rgb() and a few hsl() values to follow the latest syntax:

• rgba -> rgb
• Commas are omitted.
• The alpha value is specified as a percentage separated by a slash (/).

UPDATE: PR to update prose/examples in content --> mdn/content#30604

[bsmth]

Looks great, tnx. We might want to check in the content repo if we refer to any of these examples in this way:

in the following example, we use rgb(1,2,3) or rgba(1,2,3,4)

edit: indeed we need to update some places in content that reference the examples in prose.

Need update:

• Learn/CSS/CSS_layout/Positioning
• Learn/CSS/Building_blocks/Backgrounds_and_borders
• Learn/CSS/Building_blocks/Advanced_styling_effects
• Learn/CSS/CSS_layout/Media_queries
  • (Walkthrough: a simple mobile-first layout)

Look okay to me:

• Learn/CSS/Building_blocks/The_box_model
• Learn/CSS/Building_blocks/Debugging_CSS
• Learn/CSS/CSS_layout/Floats_skills
• Learn/CSS/CSS_layout/Grid_skills

[teoli2003]

I think that they are missing returns at the end of some of these files.

[bsmth]

I think that they are missing returns at the end of some of these files.

yeah let's add in this PR. I will commit your suggestions, tnx

[bsmth]

I think that they are missing returns at the end of some of these files.

I've done the rest in bfe1480

[dipikabh]

Thanks for reviewing, @bsmth.

edit: indeed we need to update some places in content that reference the examples in prose.

Yeah, let me open a content PR alongside before merging this one

[dipikabh]

Updated the following:

• Learn/CSS/Building_blocks/Backgrounds_and_borders
• Learn/CSS/Building_blocks/Advanced_styling_effects
• Learn/CSS/Building_blocks/Values_and_units
• Learn/CSS/CSS_layout/Media_queries
• Learn/CSS/CSS_layout/Positioning

mdn/content#30604

[dipikabh]

Merging this one now