update 2017.02.07 Some students are asking about the transparency of dots. If you read the style carefully, you can find that the origin is presented by the i tag. Just change the i tag Changing the background color to rgba can achieve the goal.
p > i {width:8px;height:8px;background:rgba(255,255,255,.3);border-radius:50%;position:absolute;top:50%;margin-top:-4px;left:8px;}
Learning front-end. Try doing it.
If the white dot needs to be transparent, the underlying background can be seen. How to do this