The Phantom browser extension can appear in two ways: popup mode and side panel mode. Phantom opens in popup mode by default. If set to side panel mode, the extension persists in that state.
Popup mode
Phantom opens in a small window on top of your current browser tab.
Side panel mode
Phantom opens on the right side of your browser window and stays visible as you switch tabs or use apps.
Switch between two modes
Click the side panel icon (looks like a sidebar) in the upper right to switch to side panel mode.
To return to popup mode, click the exit icon (two opposing arrows) in the upper right.
Resize the side panel
Drag the panel edge left or right to make it wider or narrower.
To secure Phantom while leaving it open in the side panel, go to Settings and click Lock Wallet.