The inspector is a feature in Design Mode that allows you to identify and select specific elements for styling. It also displays an element’s border, margins, and padding when you select the element. Margins are represented by orange, and padding is purple.
As you mouse over elements in the viewport, a tooltip displays the style hierarchy for the element your mouse pointer is touching. Right-clicking and then clicking one of the Edit options in the menu opens the style options for that element in the options panel (see Targeting Elements for Styling: Levels of Customization for information about the Edit options).
Toggling the Inspector On/Off
To switch off the inspector, click the Toggle Inspector
button in the menu bar. If the inspector is disabled, you have only the ability to open block options (not design options) or change a block’s type. You can still select elements in the element tree of the Design Editor.
Handy Tip: You can also toggle inspector with a shortcut. CMD + I on a Mac and CTRL + I on Windows!