8. A non-transitory computer-readable medium on which is encoded program code comprising: program code for receiving design information relating to one or more operating environments on which content will be provided, the design information comprising a shape, size, or position attribute for one or more assets to be displayed in the content provided on the one or more operating environments; program code for determining, based on an operating environment, one or more constraints associated with an asset to be displayed in the content provided on the operating environment, the one or more constraints determined using the design information; program code for receiving an asset selection or modification of the asset, the selection or modification restricted by the one or more constraints associated with the asset; and program code for providing the content for display on the operating environment, the content comprising the asset.
8. A non-transitory computer-readable medium on which is encoded program code comprising: program code for receiving design information relating to one or more operating environments on which content will be provided, the design information comprising a shape, size, or position attribute for one or more assets to be displayed in the content provided on the one or more operating environments; program code for determining, based on an operating environment, one or more constraints associated with an asset to be displayed in the content provided on the operating environment, the one or more constraints determined using the design information; program code for receiving an asset selection or modification of the asset, the selection or modification restricted by the one or more constraints associated with the asset; and program code for providing the content for display on the operating environment, the content comprising the asset. 18. The non-transitory computer-readable medium of claim 8 , further comprising: program code for using the design information to determine multiple assets for the content for multiple operating environments; program code for determining associated constraints for the multiple assets on multiple operating environments using the design information; and program code for receiving asset selections or modifications of the multiple assets, the selections or modifications restricted by the constraints associated with the multiple assets.