I want to know how I can make my own blogger template to use for my blog. When I open HTML editor from Blogger the code seems to be a strange mix of HTML, XML and CSS. I also sometimes notice variables and other things. I want to know what language I could use to make a responsive website with CSS styles. I used to use pre-created templates from the internet but it seems better to get my own design and be able to modify it.
The Blogger.com which is a content management system that used itself for managing its content. Due to the related news, their backend (to see what backend is you can check the following link: Learn to become backend developer) is written in python and the frontend (to learn more about frontend you should check this out: Learn to become frontend developer) used HTML5, CSS3, and various open-source libraries of JavaScript.
But if you want to know what language you need to use to create a blog, I would say anything you feel more convenient with, that doesn't really matter to use which technology or framework, you can use blogger itself or other CMS creators like, WordPress, Drupal and so on, and also yes, you can build one from scratch with trending frontend CSS frameworks like these ones and JS libraries like these ones and at last backend frameworks like these ones mentioned here.
Also, you can find the best practices and examples in w3schools or css-tricks and some other known ones.