fix: #1059 - upload button in form element in dark view has problem

src/scss/layout/_dark.scss

@@ -24,6 +24,8 @@ body:not(.theme-dark) .hide-theme-light {
     --#{$variable-prefix}border-color: #{$dark-mode-border-color};
     --#{$variable-prefix}border-color-light: #{$dark-mode-border-color-light};
 
+    --#{$variable-prefix}btn-color: #{$dark};
+
     color: $dark-mode-text;
     background-color: $dark-mode-darken;
   }

src/scss/ui/forms/_form-custom.scss

@@ -14,3 +14,13 @@ Remove the cancel buttons in Chrome and Safari on macOS.
   -webkit-appearance: none;
 }
 
+
+.form-control {
+  &::file-selector-button {
+    background-color: var(--#{$variable-prefix}btn-color, #{$form-file-button-bg});
+  }
+
+  &:hover:not(:disabled):not([readonly])::file-selector-button {
+    background-color: var(--#{$variable-prefix}btn-color, #{$form-file-button-hover-bg});
+  }
+}
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