The Default 3.0 design theme of Webasyst and most other themes available in your Installer are automatically adjusted to various devices it is viewed on: PC, laptop, tablet, smartphone. To ensure that your main design theme is displayed on mobile devices, select it in the properties of all routing rules (settlements) in the "Structure" screen of your Site app as shown below.
Separate design theme for mobile devices
For mobile devices, you can also select a different design theme to replace that used on PCs. To do so, choose and install the desired theme in your Installer app and then select that additional theme for mobile devices as shown in the above example.