Hi @Darius_St_Clair.
You can try Paul’s suggestion with the CSS snippet at the bottom of this message. (Sorry for the length - I’m not able to upload just the file.)
Note that enabling custom CSS will disable all theme preferences, preventing you from switching to light mode. Also, there are a few things that can’t currently be customized via custom CSS, like the colors used by the formula editor, so this won’t be a 100% match for the Grist dark theme.
Site-level theme preferences were among some of the ideas that were brought up for future enhancements to themes, which would work well for the use case of enforcing a particular theme. It’s not on our immediate roadmap, but we’re always listening to feedback from our users to prioritize what we work on next.
George
:root {
--grist-theme-text: #EFEFEF;
--grist-theme-text-light: #A4A4A4;
--grist-theme-text-dark: #FFFFFF;
--grist-theme-text-error: #FF6666;
--grist-theme-text-danger: #FFA500;
--grist-theme-text-disabled: #A4A4A4;
--grist-theme-page-bg: #262633;
--grist-theme-page-backdrop: black;
--grist-theme-page-panels-main-panel-bg: #32323F;
--grist-theme-page-panels-left-panel-bg: #262633;
--grist-theme-page-panels-right-panel-bg: #262633;
--grist-theme-page-panels-top-header-bg: #32323F;
--grist-theme-page-panels-bottom-footer-bg: #32323F;
--grist-theme-page-panels-border: #57575F;
--grist-theme-page-panels-border-resizing: #1DA270;
--grist-theme-page-panels-side-panel-opener-fg: #A4A4A4;
--grist-theme-page-panels-side-panel-opener-active-fg: #FFFFFF;
--grist-theme-page-panels-side-panel-opener-active-bg: #1DA270;
--grist-theme-add-new-circle-fg: #FFFFFF;
--grist-theme-add-new-circle-bg: #157A54;
--grist-theme-add-new-circle-hover-bg: #0A5438;
--grist-theme-add-new-circle-small-fg: #FFFFFF;
--grist-theme-add-new-circle-small-bg: #1DA270;
--grist-theme-add-new-circle-small-hover-bg: #157A54;
--grist-theme-top-bar-button-primary-fg: #1DA270;
--grist-theme-top-bar-button-secondary-fg: #A4A4A4;
--grist-theme-top-bar-button-disabled-fg: #69697D;
--grist-theme-top-bar-button-error-fg: FF6666;
--grist-theme-notifications-panel-header-bg: #262633;
--grist-theme-notifications-panel-body-bg: #32323F;
--grist-theme-notifications-panel-border: #69697D;
--grist-theme-toast-text: #FFFFFF;
--grist-theme-toast-text-light: #929299;
--grist-theme-toast-bg: #040404;
--grist-theme-toast-error-icon: #D0021B;
--grist-theme-toast-error-bg: #D0021B;
--grist-theme-toast-success-icon: #009058;
--grist-theme-toast-success-bg: #009058;
--grist-theme-toast-warning-icon: #F9AE41;
--grist-theme-toast-warning-bg: #DD962C;
--grist-theme-toast-info-icon: #3B82F6;
--grist-theme-toast-info-bg: #3B82F6;
--grist-theme-toast-control-fg: #16B378;
--grist-theme-toast-control-info-fg: #87B2F9;
--grist-theme-tooltip-fg: white;
--grist-theme-tooltip-bg: rgba(0, 0, 0, 0.75);
--grist-theme-tooltip-icon: #A4A4A4;
--grist-theme-tooltip-close-button-fg: white;
--grist-theme-tooltip-close-button-hover-fg: black;
--grist-theme-tooltip-close-button-hover-bg: white;
--grist-theme-modal-bg: #32323F;
--grist-theme-modal-backdrop: rgba(0,0,0,0.6);
--grist-theme-modal-border: #57575F;
--grist-theme-modal-border-dark: #69697D;
--grist-theme-modal-border-hover: #A4A4A4;
--grist-theme-modal-shadow-inner: #000000;
--grist-theme-modal-shadow-outer: #000000;
--grist-theme-modal-close-button-fg: #A4A4A4;
--grist-theme-modal-backdrop-close-button-fg: #1DA270;
--grist-theme-modal-backdrop-close-button-hover-fg: #157A54;
--grist-theme-popup-bg: #32323F;
--grist-theme-popup-shadow-inner: #000000;
--grist-theme-popup-shadow-outer: #000000;
--grist-theme-popup-close-button-fg: #A4A4A4;
--grist-theme-progress-bar-fg: #1DA270;
--grist-theme-progress-bar-error-fg: #FF6666;
--grist-theme-progress-bar-bg: #69697D;
--grist-theme-link: #1DA270;
--grist-theme-link-hover: #1DA270;
--grist-theme-hover: rgba(111,111,117,0.6);
--grist-theme-hover-light: rgba(111,111,117,0.4);
--grist-theme-cell-editor-fg: #FFFFFF;
--grist-theme-cell-editor-bg: #32323F;
--grist-theme-cursor: #1DA270;
--grist-theme-cursor-inactive: rgba(29,162,112,0.5);
--grist-theme-cursor-readonly: #A4A4A4;
--grist-theme-table-header-fg: #EFEFEF;
--grist-theme-table-header-selected-fg: #EFEFEF;
--grist-theme-table-header-bg: #262633;
--grist-theme-table-header-selected-bg: #414358;
--grist-theme-table-header-border: #57575F;
--grist-theme-table-header-border-dark: #69697D;
--grist-theme-table-body-bg: #32323F;
--grist-theme-table-body-border: #69697D;
--grist-theme-table-add-new-bg: #4A4A5D;
--grist-theme-table-scroll-shadow: #000000;
--grist-theme-table-frozen-columns-border: #A4A4A4;
--grist-theme-table-drag-drop-indicator: #A4A4A4;
--grist-theme-table-drag-drop-shadow: rgba(111,111,117,0.6);
--grist-theme-card-compact-widget-bg: #262633;
--grist-theme-card-compact-record-bg: #32323F;
--grist-theme-card-blocks-bg: #404150;
--grist-theme-card-form-label: #A4A4A4;
--grist-theme-card-compact-label: #A4A4A4;
--grist-theme-card-blocks-label: #A4A4A4;
--grist-theme-card-form-border: #69697D;
--grist-theme-card-compact-border: #69697D;
--grist-theme-card-editing-layout-bg: rgba(85, 85, 99, 0.2);
--grist-theme-card-editing-layout-border: #69697D;
--grist-theme-card-list-form-border: #57575F;
--grist-theme-card-list-blocks-border: #57575F;
--grist-theme-selection: rgba(22,179,120,0.15);
--grist-theme-selection-opaque-fg: white;
--grist-theme-selection-opaque-bg: #2F4748;
--grist-theme-selection-opaque-dark-bg: #253E3E;
--grist-theme-widget-bg: #32323F;
--grist-theme-widget-border: #57575F;
--grist-theme-widget-active-border: #1DA270;
--grist-theme-widget-inactive-stripes-light: #262633;
--grist-theme-widget-inactive-stripes-dark: #32323F;
--grist-theme-pinned-doc-footer-bg: #32323F;
--grist-theme-pinned-doc-border: #57575F;
--grist-theme-pinned-doc-border-hover: #A4A4A4;
--grist-theme-pinned-doc-editor-bg: #57575F;
--grist-theme-raw-data-table-border: #57575F;
--grist-theme-raw-data-table-border-hover: #A4A4A4;
--grist-theme-control-fg: #1DA270;
--grist-theme-control-primary-fg: #FFFFFF;
--grist-theme-control-primary-bg: #1DA270;
--grist-theme-control-secondary-fg: #A4A4A4;
--grist-theme-control-hover-fg: #157A54;
--grist-theme-control-primary-hover-bg: #157A54;
--grist-theme-control-secondary-hover-fg: #EFEFEF;
--grist-theme-control-secondary-hover-bg: #57575F;
--grist-theme-control-disabled-fg: #A4A4A4;
--grist-theme-control-disabled-bg: #69697D;
--grist-theme-control-primary-disabled: #5F8C7B;
--grist-theme-control-border: #11B683;
--grist-theme-checkbox-bg: #32323F;
--grist-theme-checkbox-disabled-bg: #69697D;
--grist-theme-checkbox-border: #69697D;
--grist-theme-checkbox-border-hover: #57575F;
--grist-theme-move-docs-selected-fg: #FFFFFF;
--grist-theme-move-docs-selected-bg: #1DA270;
--grist-theme-move-docs-disabled-bg: #69697D;
--grist-theme-filter-bar-button-saved-fg: #FFFFFF;
--grist-theme-filter-bar-button-saved-bg: #555563;
--grist-theme-filter-bar-button-saved-hover-bg: #69697D;
--grist-theme-icon-button-fg: #FFFFFF;
--grist-theme-icon-button-primary-bg: #1DA270;
--grist-theme-icon-button-primary-hover-bg: #157A54;
--grist-theme-icon-button-secondary-bg: #69697D;
--grist-theme-icon-button-secondary-hover-bg: #A4A4A4;
--grist-theme-left-panel-page-hover-bg: rgba(111,111,117,0.25);
--grist-theme-left-panel-active-page-fg: #EFEFEF;
--grist-theme-left-panel-active-page-bg: #555563;
--grist-theme-left-panel-disabled-page-fg: #69697D;
--grist-theme-left-panel-page-options-fg: #A4A4A4;
--grist-theme-left-panel-page-options-hover-fg: #FFFFFF;
--grist-theme-left-panel-page-options-hover-bg: #69697D;
--grist-theme-left-panel-page-options-selected-hover-bg: #A4A4A4;
--grist-theme-left-panel-page-initials-fg: white;
--grist-theme-left-panel-page-initials-bg: #929299;
--grist-theme-right-panel-tab-fg: #EFEFEF;
--grist-theme-right-panel-tab-bg: #262633;
--grist-theme-right-panel-tab-icon: #A4A4A4;
--grist-theme-right-panel-tab-icon-hover: #1DA270;
--grist-theme-right-panel-tab-hover-bg: rgba(111,111,117,0.6);
--grist-theme-right-panel-tab-selected-fg: #FFFFFF;
--grist-theme-right-panel-tab-selected-bg: #1DA270;
--grist-theme-right-panel-tab-button-hover-bg: #157A54;
--grist-theme-right-panel-subtab-fg: #1DA270;
--grist-theme-right-panel-subtab-selected-fg: #EFEFEF;
--grist-theme-right-panel-subtab-selected-underline: #1DA270;
--grist-theme-right-panel-subtab-hover-fg: #157A54;
--grist-theme-right-panel-subtab-hover-underline: #1DA270;
--grist-theme-right-panel-disabled-overlay: #262633;
--grist-theme-right-panel-toggle-button-enabled-fg: #FFFFFF;
--grist-theme-right-panel-toggle-button-enabled-bg: #555563;
--grist-theme-right-panel-toggle-button-enabled-hover-fg: #D9D9D9;
--grist-theme-right-panel-toggle-button-disabled-fg: #FFFFFF;
--grist-theme-right-panel-toggle-button-disabled-bg: #333333;
--grist-theme-right-panel-field-settings-bg: #414358;
--grist-theme-right-panel-field-settings-button-bg: #57575F;
--grist-theme-document-history-snapshot-fg: #EFEFEF;
--grist-theme-document-history-snapshot-selected-fg: #EFEFEF;
--grist-theme-document-history-snapshot-bg: #32323F;
--grist-theme-document-history-snapshot-selected-bg: #555563;
--grist-theme-document-history-snapshot-border: #69697D;
--grist-theme-document-history-activity-text: #EFEFEF;
--grist-theme-document-history-activity-text-light: #A4A4A4;
--grist-theme-accent-icon: #1DA270;
--grist-theme-accent-border: #1DA270;
--grist-theme-accent-text: #1DA270;
--grist-theme-input-fg: #EFEFEF;
--grist-theme-input-bg: #32323F;
--grist-theme-input-disabled-fg: #A4A4A4;
--grist-theme-input-disabled-bg: #262633;
--grist-theme-input-placeholder-fg: #A4A4A4;
--grist-theme-input-border: #69697D;
--grist-theme-input-valid: #1DA270;
--grist-theme-input-invalid: #FF6666;
--grist-theme-input-focus: #5E9ED6;
--grist-theme-input-readonly-bg: #262633;
--grist-theme-input-readonly-border: #69697D;
--grist-theme-choice-entry-bg: #32323F;
--grist-theme-choice-entry-border: #69697D;
--grist-theme-choice-entry-border-hover: #A4A4A4;
--grist-theme-select-button-fg: #EFEFEF;
--grist-theme-select-button-placeholder-fg: #A4A4A4;
--grist-theme-select-button-disabled-fg: #A4A4A4;
--grist-theme-select-button-bg: #32323F;
--grist-theme-select-button-border: #69697D;
--grist-theme-select-button-border-invalid: #FF6666;
--grist-theme-menu-text: #A4A4A4;
--grist-theme-menu-light-text: #A4A4A4;
--grist-theme-menu-bg: #32323F;
--grist-theme-menu-subheader-fg: #EFEFEF;
--grist-theme-menu-border: #69697D;
--grist-theme-menu-shadow: #000000;
--grist-theme-menu-item-fg: #FFFFFF;
--grist-theme-menu-item-selected-fg: #FFFFFF;
--grist-theme-menu-item-selected-bg: #1DA270;
--grist-theme-menu-item-disabled-fg: #69697D;
--grist-theme-menu-item-icon-fg: #A4A4A4;
--grist-theme-menu-item-icon-selected-fg: #FFFFFF;
--grist-theme-menu-item-link-fg: #1DA270;
--grist-theme-menu-item-link-selected-fg: #157A54;
--grist-theme-menu-item-link-selected-bg: #484859;
--grist-theme-autocomplete-match-text: #1DA270;
--grist-theme-autocomplete-selected-match-text: #0A5438;
--grist-theme-autocomplete-item-selected-bg: #69697D;
--grist-theme-search-border: #69697D;
--grist-theme-search-prev-next-button-fg: #A4A4A4;
--grist-theme-search-prev-next-button-bg: #24242F;
--grist-theme-loader-fg: #1DA270;
--grist-theme-loader-bg: #69697D;
--grist-theme-site-switcher-active-fg: #FFFFFF;
--grist-theme-site-switcher-active-bg: #000000;
--grist-theme-doc-menu-doc-options-fg: #69697D;
--grist-theme-doc-menu-doc-options-hover-fg: #A4A4A4;
--grist-theme-doc-menu-doc-options-hover-bg: #69697D;
--grist-theme-shortcut-key-fg: #FFFFFF;
--grist-theme-shortcut-key-primary-fg: #17B378;
--grist-theme-shortcut-key-secondary-fg: #A4A4A4;
--grist-theme-shortcut-key-bg: #32323F;
--grist-theme-shortcut-key-border: #A4A4A4;
--grist-theme-breadcrumbs-tag-fg: white;
--grist-theme-breadcrumbs-tag-bg: #929299;
--grist-theme-breadcrumbs-tag-alert-bg: #D0021B;
--grist-theme-widget-picker-primary-bg: #32323F;
--grist-theme-widget-picker-secondary-bg: #262633;
--grist-theme-widget-picker-item-fg: #FFFFFF;
--grist-theme-widget-picker-item-selected-bg: rgba(111,111,117,0.6);
--grist-theme-widget-picker-item-disabled-bg: rgba(111,111,117,0.6);
--grist-theme-widget-picker-icon: #A4A4A4;
--grist-theme-widget-picker-primary-icon: #1DA270;
--grist-theme-widget-picker-summary-icon: #1DA270;
--grist-theme-widget-picker-border: rgba(111,111,117,0.6);
--grist-theme-widget-picker-shadow: #000000;
--grist-theme-code-view-text: #D2D2D2;
--grist-theme-code-view-keyword: #D2D2D2;
--grist-theme-code-view-comment: #888888;
--grist-theme-code-view-meta: #7CD4FF;
--grist-theme-code-view-title: #ED7373;
--grist-theme-code-view-params: #D2D2D2;
--grist-theme-code-view-string: #ED7373;
--grist-theme-code-view-number: #ED7373;
--grist-theme-importer-table-info-border: #69697D;
--grist-theme-importer-preview-border: #69697D;
--grist-theme-importer-skipped-table-overlay: rgba(111,111,117,0.6);
--grist-theme-importer-match-icon: #69697D;
--grist-theme-menu-toggle-fg: #A4A4A4;
--grist-theme-menu-toggle-hover-fg: #1DA270;
--grist-theme-menu-toggle-active-fg: #157A54;
--grist-theme-menu-toggle-bg: #32323F;
--grist-theme-menu-toggle-border: #A4A4A4;
--grist-theme-button-group-fg: #EFEFEF;
--grist-theme-button-group-light-fg: #A4A4A4;
--grist-theme-button-group-bg: unset;
--grist-theme-button-group-icon: #A4A4A4;
--grist-theme-button-group-border: #69697D;
--grist-theme-button-group-border-hover: #555563;
--grist-theme-button-group-selected-fg: #EFEFEF;
--grist-theme-button-group-light-selected-fg: #1DA270;
--grist-theme-button-group-selected-bg: #555563;
--grist-theme-button-group-selected-border: #555563;
--grist-theme-access-rules-table-header-fg: #EFEFEF;
--grist-theme-access-rules-table-header-bg: #57575F;
--grist-theme-access-rules-table-body-fg: #A4A4A4;
--grist-theme-access-rules-table-border: #A4A4A4;
--grist-theme-access-rules-column-list-border: #69697D;
--grist-theme-access-rules-column-item-fg: #EFEFEF;
--grist-theme-access-rules-column-item-bg: #57575F;
--grist-theme-access-rules-column-item-icon-fg: #A4A4A4;
--grist-theme-access-rules-column-item-icon-hover-fg: #EFEFEF;
--grist-theme-access-rules-column-item-icon-hover-bg: #A4A4A4;
--grist-theme-cell-fg: #FFFFFF;
--grist-theme-cell-bg: #32323F;
--grist-theme-cell-zebra-bg: #262633;
--grist-theme-formula-editor-bg: #282A36;
--grist-theme-chart-fg: #A4A4A4;
--grist-theme-chart-bg: #32323F;
--grist-theme-chart-legend-bg: #32323F80;
--grist-theme-chart-x-axis: #A4A4A4;
--grist-theme-chart-y-axis: #A4A4A4;
--grist-theme-comments-popup-header-bg: #262633;
--grist-theme-comments-popup-body-bg: #32323F;
--grist-theme-comments-popup-border: #69697D;
--grist-theme-comments-user-name-fg: #DFDFDF;
--grist-theme-comments-panel-topic-bg: #32323F;
--grist-theme-comments-panel-topic-border: #555563;
--grist-theme-comments-panel-resolved-topic-bg: #262634;
--scroll-bar-fg: #6B6B6B;
--scroll-bar-hover-fg: #7B7B7B;
--scroll-bar-active-fg: #8B8B8B;
--scroll-bar-bg: #2B2B2B;
--grist-theme-bg: url("img/prismpattern.png");
}