Tried with background: linear-gradient(#e66465, #9198e5);, radial-gradient(#e66465, #9198e5) & transparent

Suggested resolution

• For transparent load the underlying Three context with {alpha: true} add a console.warn() noting that setting the alpha of the underlying will potentially impact performance
• Either provide the same note as above & set the .container's background-color to the CSS string, or could possibly do some static mapping version of Explore tinting the default environment map based off of background-color #66 since we're already in a 3D context?