Question: I am a beginner web-designer. I know the basics of HTML, CSS and Javascript. I know that CSS used to style HTML docs, but is that the only way ? Can I use JavaScript to style HTML, somehow ? Or Is there any other way rather than CSS ?

Answer: 
You're also able to style HTML with HTML-attributes itself, but this way is pretty impractical and old-fashioned. Most of these techniques are deprecated and the functionality is VERY limited.
As mentioned previously, CSS is not the only way to stylize HTML but definitely the standard. If you're looking for a more programmatic way utilizing JavaScript you can look into [less](http://lesscss.org/) which (taken directly from the webpage) ...extends CSS with dynamic behavior such as variables, mixins, operations and functions and functions map one-to-one with JavaScript code, allowing you to manipulate values however you want.