title: How can I change file code colour in GitHub
body: <p>I am new to GitHub, and I noticed that when I created a new file, the code was completely grey, as shown in Fig.1: <a href="https://i.stack.imgur.com/j1zXW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/j1zXW.png" alt="enter image description here" /></a></p>
  <p>But I also noticed that other users have 'coloured' files as shown in Fig.2:
  <a href="https://i.stack.imgur.com/Zya7V.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Zya7V.png" alt="enter image description here" /></a></p>
  <p>Is it possible to make Fig.1 code coloured as well?</p>