fix(frontend): align reward modal with shared runtime

tests/widget-system/single-cover-height-contract.test.cjs

@@ -220,7 +220,6 @@ test('dead cover css is removed from every stylesheet surface', () => {
     'assets/css/main.min.css',
     'assets/css/build/public.css',
     'assets/css/build/public.min.css',
-    'assets/css/frontend/enhancements/components/base.css',
   ]) {
     const css = read(file);
     assert.doesNotMatch(css, /\.single-cover-slide[,{ ]/, `${file} 不得再包含死的 .single-cover-slide 规则`);