🏴 Black flag UTF-8 character with hex code 1F3F4

Using HEX code of Black flag in HTML file

<span> &#x1F3F4; </span>

Using Decimal code of Black flag in HTML file

<span> &#127988; </span>

Using HEX code of Black flag in CSS file for content

span { 
    content: '\1f3f4';
}