Question 1. The long horizontal lines implemented by this code are always spaced from the left and right sides of the screen. . . Looking for a way to write without spacing
<style> *{margin:0px;padding:0px;} div{border:none;box-shadow: 0 0 5px #888;border-bottom: 1px solid #ebebeb;width:100%;height:100px;background:#fff;-webkit-transform: translateZ(0);}</style><div></div>
#aa { margin:15px -50px 0px -50px; padding:0; width:auto; height:1px; background-color:#191919; overflow:hidden; box-shadow:0px 1px 2px #373737;}
<div id="aa"></div>
Shaded The css style is box-shadow, please refer to the w3school css3 part