How to make background transparent in Unity WebGL program using linear color space

Although the following solutions work well for a program using the Gamma color space, they don't work for a program using the Linear color space. How can I make background transparent?

• https://support.unity3d.com/hc/en-us/articles/208892946-How-can-I-make-the-canvas-transparent-on-WebGL-

• https://answers.unity.com/questions/1069255/embed-webgl-in-webpage-with-transparent-background.html

• https://forum.unity.com/threads/webgl-transparent-background.284699/

I tried to modify the jslib (https://forum.unity.com/threads/webgl-transparent-background.284699/#post-1880667), then I noticed that clearColor function (https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/clearColor) with an alpha value works in the Gamma color space, but doesn't work in the Linear color space. So, I think it's not a WebGL matter and it's a Unity matter.