Code blocks not rendered properly in smaller screens

I noticed an issue in which the code block in the "git log --oneline improvements" section renders badly in smaller screen. Further it also breaks the single-pagedness of the website. As a consequence, one might have to zoom in to read the post and scrolling might take you to empty space in the right. Screen shots:

• Desktop view:
  

• Mobile view (iPhone SE resolution)
  

  

  Note the scroll bar in the bottom of the page.

It would be nice to fix this by making the code blocks render in such a way that the code within the block is scrollable rather than the whole page being scrollable.

Note: Initially mentioned in https://github.com/git/git.github.io/pull/366#issuecomment-471316738

從連結的 Git Developer Pages 網站上的「git log --oneline improvements」區段開始，按照截圖中顯示的 iPhone SE 解析度重現版面配置。檢查影響程式碼區塊的回應式樣式；完成標準是程式碼本身可以水平捲動，而不會造成整個頁面溢位或產生空白區域。