Nowadays many user utilized mobile to access the web pages. Blogger has prepared templates optimized for running on mobile devices.
To enable them, you should switch back to the old version of Blogger by clicking on the "switch back" button on the top of the new blogger control panel.
Once in the old control panel, you should:
1. Click on Settings
2. Click on Email & Mobile
3. Enable: "Yes. Show mobile templates on mobile devices"
4. Click on "Save settings"
Optionally you can set the templates and change the style of the templates