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fix: CSS back to <style> for Safari/cascade reasons #9908

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Merged
maribethb merged 1 commit into from
May 20, 2026
Merged

fix: CSS back to <style> for Safari/cascade reasons #9908

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33 changes: 15 additions & 18 deletions packages/blockly/core/css.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,8 @@
*/

// Former goog.module ID: Blockly.Css
/** Has CSS already been injected? */
const injectionSites = new WeakSet<Document | ShadowRoot>();
const registeredStyleSheets: Array<CSSStyleSheet> = [];
const registeredCss: Array<string> = [];
import * as userAgent from './utils/useragent.js';

/**
Expand All @@ -17,11 +16,7 @@ import * as userAgent from './utils/useragent.js';
* @param cssContent Multiline CSS string or an array of single lines of CSS.
*/
export function register(cssContent: string) {
if (typeof window === 'undefined' || !window.CSSStyleSheet) return;

const sheet = new CSSStyleSheet();
sheet.replace(cssContent);
registeredStyleSheets.push(sheet);
registeredCss.push(cssContent);
}

/**
Expand All @@ -41,24 +36,26 @@ export function inject(
hasCss: boolean,
pathToMedia: string,
) {
if (!hasCss || typeof window === 'undefined' || !window.CSSStyleSheet) {
return;
}
if (!hasCss || typeof window === 'undefined') return;

const root = container.getRootNode() as Document | ShadowRoot;
// Only inject the CSS once.
if (injectionSites.has(root)) return;
injectionSites.add(root);

// Strip off any trailing slash (either Unix or Windows).
const mediaPath = pathToMedia.replace(/[\\/]$/, '');
const cssContent = content.replace(/<<<PATH>>>/g, mediaPath);

const sheet = new CSSStyleSheet();
sheet.replace(cssContent);
root.adoptedStyleSheets.push(sheet);

registeredStyleSheets.forEach((sheet) => root.adoptedStyleSheets.push(sheet));
const cssText = [content, ...registeredCss]
.join('\n')
.replace(/<<<PATH>>>/g, mediaPath);

const styleEl = document.createElement('style');
styleEl.id = 'blockly-common-style';
styleEl.textContent = cssText;
// Prepend so Blockly's rules sit at the start of the cascade; any user
// stylesheet declared later wins by document order. Style elements appended
// to the light DOM don't apply inside shadow roots, so for the shadow DOM
// case we prepend the style element to the shadow root itself.
(root instanceof ShadowRoot ? root : document.head).prepend(styleEl);
}

/**
Expand Down
20 changes: 9 additions & 11 deletions packages/blockly/core/renderers/common/constants.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1126,17 +1126,15 @@ export class ConstantProvider {
* @param selector The CSS selector to interpolate into the stylesheet.
*/
protected injectCSS_(root: Document | ShadowRoot, selector: string) {
if (
typeof window === 'undefined' ||
!window.CSSStyleSheet ||
injectionSites.get(selector)?.has(root)
) {
return;
}

const sheet = new CSSStyleSheet();
sheet.replace(this.getCSS_(selector).join('\n'));
root.adoptedStyleSheets.push(sheet);
if (typeof window === 'undefined') return;
if (injectionSites.get(selector)?.has(root)) return;

const styleEl = document.createElement('style');
styleEl.className = 'blockly-renderer-style';
styleEl.textContent = this.getCSS_(selector).join('\n');
// See css.ts inject() for the rationale on prepending and shadow root
// handling.
(root instanceof ShadowRoot ? root : document.head).prepend(styleEl);

const sitesForSelector =
injectionSites.get(selector) ?? new WeakSet<Document | ShadowRoot>();
Expand Down
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