zh-cn: correct the description of "CSS"

[NyanHeart]

Description

修改了关于css定义的句子，使之表达更恰当。

英文原文是Like HTML, CSS is not a programming language. It's not a markup language either. CSS is a style sheet language.
当前的中文翻译是和HTML 类似，CSS 不是编程语言，也不是标记语言，而是一门样式表语言。
句意上来说，和HTML类似后面的修饰短句都适用于HTML，造成了歧义。
更改后的表达更合适。
和HTML 类似，CSS 不是编程语言。它也不是标记语言，而是一门样式表语言。

[github-actions]

Preview URLs

• /zh-CN/docs/Learn/Getting_started_with_the_web/CSS_basics

Flaws (15)

URL: /zh-CN/docs/Learn/Getting_started_with_the_web/CSS_basics
Title: CSS 基础
Flaw count: 15

• macros:
  • /zh-CN/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state
  • /zh-CN/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_filtering_conditional_rendering does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_filtering_conditional_rendering
  • /zh-CN/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_accessibility does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_accessibility
  • /zh-CN/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_resources does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_resources
  • /zh-CN/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_getting_started does not exist but fell back to /en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_getting_started
  • and 10 more flaws omitted

[yin1999]

赞同说明的这一点，感谢 @NyanHeart