Glow

A soft shadow appears or deepens beneath the element on hover to suggest elevation.

Add a "Hover Shadow" effect (also called drop shadow on hover or elevation on hover) to [where].
A soft shadow beneath the element should deepen and spread while the pointer is over it so it looks raised, and fade back when it leaves, while the element itself stays in place.
Keep the shadow subtle enough to work in both light and dark themes, and show the same effect on keyboard focus.

Text glows like a neon tube and flickers or pulses.

Add a "Neon Glow Text" effect (also called a neon sign flicker or glowing text) to [where].
The text should glow like a neon tube with a soft, steady light, and now and then flicker off briefly like a real sign.
Keep the flicker occasional rather than rapid, since fast flashing can harm some users, and keep the glow steady for users who prefer reduced motion.

An outline grows outward from or shrinks toward the element on hover.

Add an "Outline Expand" hover effect to [where].
An outline should start flush with the element's edge and move outward to leave a small gap around it, staying there while hovered and closing back in when the pointer leaves: smooth and quick.
Draw the outline so it doesn't change the element's size or push nearby content, and show the same effect on keyboard focus.

A gradient border animates around the element and expands when the pointer is over it.

Add a "Hover Border Gradient" effect to [where].
A short gradient highlight should rest on one part of the border; while the pointer is over the element it should travel steadily around the border as the whole border brightens with a soft glow.
Animate the border only while hovered, and keep it still for users who prefer reduced motion.

The element smoothly scales up slightly when the pointer is over it.

Add a "Grow" hover effect (also called scale up) to [where].
The element should scale up slightly and smoothly while the pointer is over it, and shrink back when the pointer leaves: quick and subtle.
Keep the surrounding layout from shifting, and show the same effect on keyboard focus.

The filled background empties, leaving only an outlined button on hover.

Add a "Hollow" hover effect (also called ghost fill) to [where].
The filled background should fade away, leaving only the outline, and the label should change color to stay readable on the empty background: smooth and quick.
Keep the border the same thickness in both states so the element doesn't change size, and show the same effect on keyboard focus.