You can use the Color Palette to apply a solid color to supported objects in your project.
Open the Color Palette
Open your project in the Web editor.
Select the object you want to modify.
Click the Roller icon to open the texture menu.
Select the Color option.
The Color Palette opens, allowing you to choose a color for the selected object.
Choose a color
Use the Color Palette to select the color you want to apply to the object.
The selected color is applied immediately.
For visual reference, please refer to the below to see what the color palette looks like:

