feat: load Leaflet CSS via CDN <link> instead of bundling

Replace inline CSS import with a configurable CDN <link> to fix 404s on
marker icon PNG files (relative paths now resolve against the CDN URL).

- Remove leaflet/dist/leaflet.css import and --loader:.css=text from build
- Add css-url, css-integrity, css-crossorigin attributes on <leaflet-map>
- Derive Icon.Default.imagePath from CSS URL for JS-loaded marker icons
- Move shadow DOM setup into connectedCallback with reconnection guard
- Use CSS_ATTRS constant for observedAttributes and attributeChangedCallback

CSS attrs default to https://unpkg.com/leaflet@1.9.4/dist/leaflet.css with
SRI integrity and crossorigin='anonymous'. Custom CSS URLs drop the
default integrity; set css-integrity explicitly to re-enable SRI.

package.json

@@ -12,7 +12,7 @@
     }
   },
   "scripts": {
-    "build": "rm -rf dist && tsc --emitDeclarationOnly && esbuild src/index.ts --bundle --format=esm --loader:.css=text --outfile=dist/index.js",
+    "build": "rm -rf dist && tsc --emitDeclarationOnly && esbuild src/index.ts --bundle --format=esm --outfile=dist/index.js",
     "lint": "eslint 'src/**/*.{ts,js}'",
     "format": "prettier --write 'src/**/*.{ts,js,json,md}'",
     "prepublishOnly": "npm run build"

src/components/leaflet-map.ts

@@ -1,7 +1,11 @@
-import { Map as LMap, MapOptions } from 'leaflet';
-import leafletCSS from 'leaflet/dist/leaflet.css';
+import { Icon, Map as LMap, MapOptions } from 'leaflet';
 import { LeafletRegisterEvent } from '../core/register.js';
 
+const DEFAULT_CSS_URL = 'https://unpkg.com/leaflet@1.9.4/dist/leaflet.css';
+const DEFAULT_CSS_INTEGRITY = 'sha256-p4NxAoJBhIIN+hmNHrzRCf9tD/miZyoHS5obTRR9BMY=';
+
+const CSS_ATTRS = ['css-url', 'css-integrity', 'css-crossorigin'] as const;
+
 // ── Prop types ─────────────────────────────────────────────────────────────
 
 type NumProp = {
@@ -158,11 +162,12 @@ const TypedBase = HTMLElement as unknown as new () => HTMLElement & PropTypes;
 export class LeafletMap extends TypedBase {
   #map?: LMap;
   #container!: HTMLDivElement;
+  #cssLink?: HTMLLinkElement;
   #syncing = false;
   #mapEventHandlers = new globalThis.Map<string, () => void>();
 
   static get observedAttributes(): string[] {
-    return Object.values(PROPS).map((s) => s.attr);
+    return [...Object.values(PROPS).map((s) => s.attr), ...CSS_ATTRS];
   }
 
   // Generates a getter/setter on the prototype for every entry in PROPS.
@@ -211,19 +216,19 @@ export class LeafletMap extends TypedBase {
     }
   }
 
-  constructor() {
-    super();
+  connectedCallback() {
+    if (!this.shadowRoot) {
       this.attachShadow({ mode: 'open' });
       this.#container = document.createElement('div');
       this.#container.style.width = '100%';
       this.#container.style.height = '100%';
       this.shadowRoot!.appendChild(this.#container);
       const style = document.createElement('style');
-    style.textContent = `:host { display: block; width: 100%; height: 400px; }\n${leafletCSS}`;
+      style.textContent = ':host { display: block; width: 100%; height: 400px; }';
       this.shadowRoot!.appendChild(style);
     }
+    this.#applyCss();
 
-  connectedCallback() {
     // Read view-state from attributes directly — the getters call getCenter()/getZoom()
     // which throw if invoked before setView(), so we can't use them here.
     const lat = Number(this.getAttribute('lat') ?? 0);
@@ -280,6 +285,10 @@ export class LeafletMap extends TypedBase {
 
   attributeChangedCallback(name: string, oldValue: string | null, newValue: string | null) {
     if (oldValue === newValue || !this.#map || this.#syncing) return;
+    if (CSS_ATTRS.includes(name as (typeof CSS_ATTRS)[number])) {
+      this.#applyCss();
+      return;
+    }
     const propName = ATTR_TO_PROP.get(name);
     if (!propName) return;
     const spec = PROPS[propName] as PropDef;
@@ -288,7 +297,46 @@ export class LeafletMap extends TypedBase {
     } else if (spec.kind === 'bool-off') {
       spec.mapSet?.(this.#map, newValue === null);
     }
-    // bool-on: constructor-only, no live update
+    // skip spec.kind === 'bool-on': constructor-only, no live update
+  }
+
+  #applyCss() {
+    const sr = this.shadowRoot;
+    if (!sr) return;
+
+    if (this.#cssLink) {
+      this.#cssLink.remove();
+      this.#cssLink = undefined;
+    }
+
+    const customUrl = this.hasAttribute('css-url');
+    const url = customUrl ? this.getAttribute('css-url')! : DEFAULT_CSS_URL;
+
+    let integrity: string | undefined;
+    if (this.hasAttribute('css-integrity')) {
+      integrity = this.getAttribute('css-integrity')!;
+    } else if (!customUrl) {
+      integrity = DEFAULT_CSS_INTEGRITY;
+    }
+
+    let crossorigin: string | undefined;
+    if (this.hasAttribute('css-crossorigin')) {
+      const val = this.getAttribute('css-crossorigin');
+      crossorigin = val ?? undefined;
+    } else if (integrity) {
+      crossorigin = 'anonymous';
+    }
+
+    const link = document.createElement('link');
+    link.rel = 'stylesheet';
+    link.href = url;
+    if (integrity) link.setAttribute('integrity', integrity);
+    if (crossorigin !== undefined) link.setAttribute('crossorigin', crossorigin);
+    sr.appendChild(link);
+    this.#cssLink = link;
+
+    // Derive marker icon path from the CSS URL (replaces leaflet.css → images/)
+    Icon.Default.imagePath = url.replace(/\/[^/]+$/, '/images/');
   }
 
   #syncAttr(name: string, value: string) {