How to use the style of Markdown (blog Park) content?

problem description

there is no doubt that writing articles with markdown is really fast. But sometimes when I want to change its default style, I usually change it through style , but I find it troublesome. For example, I want to modify my own h4 to this

then I have to set a lot of style styles

the environmental background of the problems and what methods you have tried

at present, my solution is to write css styles one by one

related codes

/ / Please paste the code text below (do not replace the code with pictures)

<div style="width: 400px; background-color: -sharp548254;padding:5px 15px;border-radius: 8px;">
    <font color="-sharpFFF"><h3>
        Moment.js
    </h3></font>
</div>

<div style="width: 200px; background-color: -sharp885c5c;padding:1px 30px;margin-top: 15px;border-radius: 8px;">
    <font color="-sharpFFF"><h4>
        1.1 
    </h4></font>
</div>

<font color="green"><h3>xxxx</h3></font>

<font color="-sharp9a4141"><h4>2.1 xxxx</h4></font>

what result do you expect?

looked it up on the Internet and found no good solution. I edited the text with Youdao cloud notes"s markdown and sent it to the blog Garden. Wondering if there is a way to define a class like html, and then in the tag div .
for example:

.title{
    padding: 5px 30px;
    background-color: -sharp12b7f5;
}

<div class="title">Markdown</div>