Question Kunena 1.6 RC 3 Error (CSS2.1)

Funny tested CSS forum and here that he discovered, CSS must match (CSS2.1)

But the authors of the forum involved the code for CSS 3 such as:

That does not support CSS 1, 2, 2.1

Next, the browser Opera 9.2, 9.6, 1910, Firefox 2.0, 3.0, too, with it not working! Does not support: CSS 1 - 2 - 2.1 - 3
Next browsers that do not support:
Internet Explorer 6.0-9.0; Chrome 2.0-5.0; Opera 9.2, 9.6, 10; Safari 2.0, 3.1, 4.0, 5.0; Firefox 3.5 and 4.0 - supports

That is a miracle akin to Only works in CSS 3
Next browsers that do not support:
Internet Explorer 6.0 - 8.0; Opera 9.2, 9.6, 10; Safari 2.0, 3.1, 4.0; Firefox 2.0, 3.0, 3.6, 4.0
Only works in CSS 3
Next browsers that do not support:
Internet Explorer 6.0, 7.0, 8.0, 9.0; Opera 9.2, 9.6, 10; Safari 2.0; Firefox 2.0, 3.0, 3.6, 4.0
W3C CSS Validator results for (CSS2.1)
errors (12)
/components/com_kunena/template/default/css/kunena.forum-min.css

# Kunena div.kblock div.ktitle Property word-wrap doesn't exist: break-word break-word
# Kunena div.kblock div.kbody Property word-wrap doesn't exist: break-word break-word
# Kunena # ktab a Property-moz-border-radius-topright doesn't exist: 5px 5px
# Kunena # ktab a Property-moz-border-radius-topleft doesn't exist: 5px 5px
# Kunena # ktab a Property-webkit-border-radius-topright doesn't exist: 5px 5px
# Kunena # ktab a Property-webkit-border-radius-topleft doesn't exist: 5px 5px
# Kunena div.kmsgbody div.kmsgtext Property word-wrap doesn't exist: break-word break-word
# Kunena div.kmsgbody div.kmsgtext Property word-wrap doesn't exist: break-word break-word
# Kunena div.kmsgtext pre, # Kunena div.kmsgtext code Property word-wrap doesn't exist: normal normal
# Kunena. Kfile-input Property opacity doesn't exist in CSS level 2.1 but exists in: 0 0
# Kunena. Kfile-input Parse Error opacity = 0)
# Kunena div.kannouncement h2 Property word-wrap doesn't exist: break-word break-word

We are not staying in CSS 2.1 anymore -- most browsers can do better than that. For example ~90% of my users use relatively new browsers which support CSS3. Others have some minor things missing, but layout should be OK.

I realized that all use the new browsers ...
But it is not strange to write CSS 3, when using CSS 2.1?
During the chase two hares, you will not catch (Anton Chekhov).

Most of the CSS3 is used to fix something that cannot be done in CSS2.

Word-wrap is used to fix layout on looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong words.

Opacity is used to make our multi file upload to work in all browsers.

border-top-right-radius etc are used to make our menu prettier..

So K1.6 default template is still mostly CSS2.1, but fixing some issues by using CSS3/custom rules.

Opera this CSS 3 does not support, then under what browser this pattern is sharpened?

Beauty is good, but needed if this beauty is still such victims?
Internet Explorer, Firefox also did not understand all of this CSS 3!