The reason why the css code is initialized is to minimize compatibility issues between browsers!
Tencent QQ official website style initialization
body,ol,ul,h1,h2,h3,h4,h5,h6,p ,th,td,dl,dd,form,fieldset,legend,input,textarea,select{margin:0;padding:0}
body{font:12px"Arial Narrow",HELVETICA;background:#fff ;-webkit-text-size-adjust:100%;}
a{color:#2d374b;text-decoration:none}
a:hover{color:#cd0200;text-decoration:underline}
em{font-style :normal}
li{list-style:none}
img{border:0;vertical-align:middle}
table{border-collapse:collapse;border-spacing:0}
p{word-wrap:break-word }
Sina official website style initialization
a:hover,a:active,a:focus{color:#c00;text-decoration:underline;}
Taobao official website style initialization
body, h1, h2, h3, h4, h5, h6, hr, p, blockquote, dl, dt, dd, ul, ol, li, pre, form, fieldset, legend, button, input, textarea, th, td { margin: 0; padding:0; }
body, button, input, select, textarea { font:12px/1.5tahoma, arial, 5b8b4f53; }
h1, h2, h3, h4, h5, h6{ font-size:100%; }
address, cite, dfn, em, var { font-style:normal; }
code, kbd, pre, samp { font-family:couriernew, courier, monospace; }
small{ font-size:12px; }
ul, ol { list-style:none; }
a { text-decoration:none; }
a:hover { text-decoration:underline; }
sup { vertical-align:text-top; }
sub{ vertical- align:text-bottom; }
legend { color:#000; }
fieldset, img { border:0; }
button, input, select, textarea { font-size:100%; }
table { border-collapse: collapse; border-spacing:0; }
NetEase official website style initialization
html {overflow-y:scroll;}
body {margin:0; padding:29px00; font:12px"5B8B4F53",sans-serif;background :#ffffff;}
div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,input,textarea,blockquote,p{padding:0; margin:0;}
table,td,tr,th{font-size:12px;}
li{list-style-type:none;}
img{vertical-align:top;border:0;}
ol, ul {list-style:none;}
h1,h2,h3,h4,h5,h6{font-size:12px; font-weight:normal;}
address,cite,code,em,th {font-weight: normal; font-style:normal;}