とりあえず
/* サイドバー検索ボックスの色 */
#bookmarksPanel #search-box, #history-panel #search-box {
-moz-appearance: none !important;
background-color: var(--lwt-toolbar-field-background-color) !important;
border: 1px solid #525252 !important;
/*border: 1px solid #bdbdbd !important; /* システムのテーマ */
color: inherit !important;
}
#bookmarksPanel #search-box:hover, #history-panel #search-box:hover {
border: 1px solid rgba(0, 122, 255, .33) !important;
}
#bookmarksPanel #search-box[focused="true"], #history-panel #search-box[focused="true"] {
border: 1px solid rgba(0, 122, 255, .33) !important;
}