How to create sub md files with content that applies to the page md files - jekyll

Question

I'm creating a website using Jekyll.
so far I have four pages which are created automatically from four md files which md files are in the root of the project.
index.md
about.md
login.md
register.md
Here is the content inside my login.md file
---
layout: layout-default
title: some login title
permalink: /login
theme: secondary-theme
nav:
menu-items:
- type: text
text: Don't have an account?
- type: link
text: SIGN UP
class: button
linkPath: /register
sections:
- type: 3
class: form-section
header-line-2: Login Section!
form:
api: http://127.0.0.1:8080/login
submit-text: LOG IN
form-controls:
- label-text: EMAIL ADDRESS
input-type: email
input-placeholder: Enter your email
input-name: email
- label-text: PASSWORD
label-link-text: Forgot password?
label-link-path: #
input-type: password
input-placeholder: Enter your password
input-name: password
---
What i do is iterating the sections and applying html attribute values depending on the variables inside each section. That way i can have as many sections rendered as i want on one page. And they can also be different depending on the classes and content i put in the md file.
The problem is that if the project gets too complicated with different styles for sections and so on. I would like to separate each section content. It would be nice if i could make a folder lets say login/sections folder
and then put md files inside and then inside login.md file include these section md files. This way the code would be much more organized.
Is there way to do that, and is my approach actually good.

Answer 1

Jekyll provides the ability to include files into another files. The magic directory for this is _includes. Example:
If you create a file named _includes/sections/s1.html, you can include that into any other file with the following tag:
{% include sections/s1.html %}
This approach works for:
including HTML file into HTML
including HTML file into Markdown (since Markdown can contain HTML code)
including Markdown into Markdown
If you want to include a Markdown file into a HTML, you have to use some trick:
{% capture m %}{% include sections/s1.md %}{% endcapture %}
{{ m | markdownify }}