Back up all data.
Triple-click anywhere in the line below to select it:
defaults write -app Safari WebKitPDFScaleFactor -float 1.5
Copy the selected text to the Clipboard (command-C).
Quit Safari. Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window (command-V).
Launch Safari and test.
Problem has resolved by itself through one of the tune-up operations.
Retrieving data ...