Looking for the title and or author of a long ago favorite; I have searched the web for it on and off for years.
I read a paperback novel about 40 years ago; it was probably a used book at that time. Probably pre-1975 publication. In my memory it was written in the style of Andre Norton I have looked through her Wikipedia Bibliography, but I am not finding it. It was a young adult sci-fi novel.
Plot; a young woman (gender was not strong, but I remember the main character being female) can see different colored circles floating around. When she looks at them just right, she can jump through to another universe. In the other universe, things change. She might become a lion, or maybe she is carrying a seed that becomes a net in the other universe.
Two bad guys are chasing her around the different dimensions, I recall one scene where they are all sliding down an icy slope and she jumps through a portal, to escape the bad guys.
There were a lot of complexities about, dimensions, what became what, different colors of portals and such.