feat: render Calibri Light with the bundled Carlito

Word's default theme heading font, so every Word file with a Title or a
heading references it. Without a face it dropped to the browser's serif —
a serif heading at the wrong width.

src/lib/styles/styleSheet.ts

@@ -203,6 +203,7 @@ export function cssFontFamily(name: string): string {
 export const DEFAULT_SINGLE_LINE_HEIGHT = 1.15;
 const SINGLE_LINE_HEIGHT: Record<string, number> = {
   Calibri: 1.2208,
+  'Calibri Light': 1.2208,
   Carlito: 1.2208,
   'Courier New': 1.1333,
   'Liberation Mono': 1.1333,

src/styles/global.css

@@ -88,6 +88,30 @@
   src: local('Calibri Bold Italic'), local('Carlito Bold Italic'), url('../assets/fonts/Carlito-BoldItalic.ttf') format('truetype');
 }
 
+/* Calibri Light → Carlito. Word's default theme heading font; Carlito has no light
+   cut, so LibreOffice renders it with the regular one too. */
+@font-face {
+  font-family: 'Calibri Light';
+  font-style: normal;
+  font-weight: 400;
+  font-display: swap;
+  src: local('Calibri Light'), local('Carlito'), url('../assets/fonts/Carlito-Regular.ttf') format('truetype');
+}
+@font-face {
+  font-family: 'Calibri Light';
+  font-style: normal;
+  font-weight: 700;
+  font-display: swap;
+  src: local('Calibri Light'), local('Carlito Bold'), url('../assets/fonts/Carlito-Bold.ttf') format('truetype');
+}
+@font-face {
+  font-family: 'Calibri Light';
+  font-style: italic;
+  font-weight: 400;
+  font-display: swap;
+  src: local('Calibri Light Italic'), local('Carlito Italic'), url('../assets/fonts/Carlito-Italic.ttf') format('truetype');
+}
+
 /* Arial → Liberation Sans */
 @font-face {
   font-family: 'Arial';