三橫 icon

//=== https://www.abeautifulsite.net/the-unicode-character-for-menu-icons

three-line navigation menu icon

...
This is actually a Chinese glyph (the trigram for heaven),
but in the western world you'd be more apt to recognize it as
the "hamburger" navigation menu icon.

It's available as the following HTML entity:
☰

Here's how you might use it in a navigation menu:
☰

...


//=== https://www.w3schools.com/howto/howto_css_menu_icon.asp

use CSS to create menu icon

html snippet
<div></div>
<div></div>
<div></div>


css snippet
div {
width: 35px;
height: 5px;
background-color: black;
margin: 6px 0;
}