W pliku [twójTheme]/assets/css/editor-blocks.css należy doidać poniższy skrawek kodu do stylów
/* ###############################################
DARK THEME sajan
############################################### */
.editor-styles-wrapper {
max-width: 100% !important;
background-color: #cdc8c8!important;
margin: 0!important;
padding-left: 50px!important;
}
.edit-post-header {
background-color: #9f9f9f;
}
.components-button.is-tertiary {
color: #004070;
font-weight: bold;
}
.components-button.is-primary:disabled, .components-button.is-primary:disabled:active:enabled, .components-button.is-primary[aria-disabled=true], .components-button.is-primary[aria-disabled=true]:active:enabled, .components-button.is-primary[aria-disabled=true]:enabled {
color: #cdd5dd;
background: #004070;
border-color: #004070;
font-weight: bold;
opacity: 1;
outline: none;
}
.components-button.is-primary {
background: #004070;
}