@-moz-document domain("5ch.net"), domain("bbspink.com") {
.post {
margin-left: 170px !important;
　border: 1px double black !important;
border-style: solid !important;
border-radius: 5px !important;
filter: drop-shadow(2px 2px 2px #0000008a) !important;
}

.search-header, .searchbar {
/*border: none !important;*/
/*border: 1px #b9b9b9 solid !important;*/
margin-top: 0px !important;
margin-left: 50px !important;
margin-right: 50px !important;
background: #eee !important;
border-radius: 45px !important;
filter: drop-shadow(3px 3px 3px #0000008a) !important;
}
}

おかしいところあるっぽいけど好みに調整してください
ベースにしたcss
https://userstyles.org/styles/149788/5ch-floralwhite