About symmetry

Key: filter: drop-shadow (vertical and horizontal position, color) that can copy graphics, ha ha ha.

1. FIG effect: Effect Address: https://scrimba.com/c/c664NvUp

2.HTML code:

<div class="main"></div>

  CSS code:

HTML, body { 
    margin : 0 ; 
    padding : 0 ; 
} / * set all the elements in width, height including border, padding, Content * / 
* { 
    Box-Sizing : border-Box ; 
} 
body { 
    height : 100vh ; 
    the display : Flex ; 
    The justify-Content : Center ; 
    align = left-items : Center ; 
    font-size : 13px ; 
} 
.main {

    width : 4em ; 
    height : 4em ; 
    border : 1em Solid Blue ; 
    border-RADIUS : 50% ;
     / * filter: drop-Shadow (up and down position, color) * / 
    filter : drop-Shadow (5em 0 0 Blue)
     / * centered their own way, ha ha ha * / 
}