Module:Infobox/styles.css

/* === Force infobox background to white in all modes === */

/* Light/default (also affects pages without any dark-mode class) */
.infobox,
.infobox-subbox,
.infobox-table {
  background-color: #fff !important;
  color: #000; /* keep text legible on white */
}

/* Night mode override: force white instead of #1f1f23 */
@media screen {
  html.skin-theme-clientpref-night .infobox,
  html.skin-theme-clientpref-night .infobox-full-data:not(.notheme) > div:not(.notheme)[style] {
    background: #fff !important;
    color: #000 !important;
  }
}

/* OS-driven dark mode override: force white instead of #1f1f23 */
@media screen and (prefers-color-scheme: dark) {
  html.skin-theme-clientpref-os .infobox,
  html.skin-theme-clientpref-os .infobox-full-data:not(.notheme) > div:not(.notheme)[style] {
    background: #fff !important;
    color: #000 !important;
  }
}