change color markdown code example

Example 1: markdown: text size

 This is my text number1 

  This is my text number 2 
 
  This is my text number 3 
 
  This is my text number 4 
 
  This is my text number 5 
 
  This is my text number 6

Example 2: markdown color

// Via HTML:
some *red* text.

Example 3: font size markdown

 This is my text number1 

  This is my text number 2 

Example 4: markdown codebox text color

```json
{
  "firstName": "John",
  "lastName": "Smith",
  "age": 25
}
```