theme.css 파일에서
#modal-siteinfo 로 시작하는 부분을 아래 내용으로 전체 변경
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#modal-siteinfo { display:flex; justify-content:center; align-items:center; }
#modal-siteinfo:not(.in) { opacity:0; z-index:-999; visibility:hidden; }
#modal-siteinfo .modal-dialog { margin:0; }
#modal-siteinfo .head { text-align:center; font-size:1.5rem; color:#fff; font-weight:600; }
#modal-siteinfo button[aria-label="Close"] { position:absolute; right:0; top:0; width:30px; height:30px; }
#modal-siteinfo button[aria-label="Close"]:before,
#modal-siteinfo button[aria-label="Close"]:after { content:""; position:absolute; left:50%; top:calc(50% - 15px); width:2px; height:30px; background:#fff; }
#modal-siteinfo button[aria-label="Close"]:before { transform:rotate(45deg); }
#modal-siteinfo button[aria-label="Close"]:after { transform:rotate(-45deg); }
#modal-siteinfo .modal-content { padding:30px; margin-top:10px; }

#modal-siteinfo .modal-content .desc { overflow-y:auto; height:400px; max-height:90vh; font-size:.875rem; }

#modal-siteinfo .btns { display:flex; justify-content:center; margin-top:20px; }
#modal-siteinfo .btns button { position:relative; width:120px; height:auto; padding:10px 0; margin:0 2px; border-radius:99px; text-align:center; cursor:pointer; color:#fff; }
#modal-siteinfo .btns button:before,
#modal-siteinfo .btns button:after { display:none; }
#modal-siteinfo .btns button.btn-cancel { background:#333; border:2px solid #333; }
#modal-siteinfo .btns button.btn-ok { background:var(--main-color1); border:2px solid var(--main-color1); }
#modal-siteinfo .btns button:hover { background:none; }
#modal-siteinfo .btns button.btn-cancel:hover { color:#333; }
#modal-siteinfo .btns button.btn-ok:hover { color:var(--main-color1); }
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해당 게시판 스킨 style.css 에서
#modal-siteinfo 로 시작하는 부분 전체삭제
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테마폴더 > menu > quick-menu.css 에서
#modal-siteinfo 로 시작하는 부분 전체삭제