force alpha to 1 when using background color as inverted foreground color.

src/browser/renderer/atlas/DynamicCharAtlas.ts

@@ -11,6 +11,7 @@ import { LRUMap } from 'browser/renderer/atlas/LRUMap';
 import { isFirefox, isSafari } from 'common/Platform';
 import { IColor } from 'browser/Types';
 import { throwIfFalsy } from 'browser/renderer/RendererUtils';
+import { fromRgba, toCss } from 'browser/Color';
 
 // In practice we're probably never going to exhaust a texture this large. For debugging purposes,
 // however, it can be useful to set this to a really tiny value, to verify that LRU eviction works.
@@ -253,7 +254,13 @@ export class DynamicCharAtlas extends BaseCharAtlas {
       `${fontStyle} ${fontWeight} ${this._config.fontSize * this._config.devicePixelRatio}px ${this._config.fontFamily}`;
     this._tmpCtx.textBaseline = 'middle';
 
-    this._tmpCtx.fillStyle = this._getForegroundColor(glyph).css;
+    const fgColor = this._getForegroundColor(glyph);
+    this._tmpCtx.fillStyle = fgColor.css;
+
+    if (glyph.fg === INVERTED_DEFAULT_COLOR) {
+      const rgba = fromRgba(fgColor.rgba);
+      this._tmpCtx.fillStyle = toCss(rgba[0], rgba[1], rgba[2]);
+    }
 
     // Apply alpha to dim the character
     if (glyph.dim) {