iPhone (Safari): tap the โขโขโข icon in the lower right, select Share (), tap View More (the โ icon), then scroll down and select Add to Home Screen.
iPhone (Chrome): tap the Share icon () in the toolbar, tap View More (the โ icon), then scroll down and tap Add to Home Screen.
Android (Chrome): tap the โฎ menu in the top right, then find and select Install and Create Shortcut.