That's Meridian a series published by the now defunct CrossGen Comics.
Here's the blurb from the first volume of the series:
Meridian is the story of Sephie, a sheltered young girl whose life
resembles nothing so much as a fairy tale. The beloved only child of
the Minister of Meridian, she grows up with an entire floating city as
her playground. Then her father dies, and she inherits a sigil imbued
with the power to create. So does her wicked Uncle Ilahn, except that
his powers are bent on destruction and domination. Suddenly Sephie
finds herself at the center of a power struggle, and quickly she
learns that there is more than love in the world. Kidnapped to the
world of Calador, Sephie's journey home to Meridian puts her in the
path of many people good and bad that help her grow up and counter
Ilahn's plans to take over her world.
The series ran for 44 issues (July 2000 - April 2004) but only the first 26 issues were collected:
- Meridian Volume 1: Flying Solo [1 - 7]
- Meridian Volume 2: Going to Ground [8 - 14]
- Meridian Volume 3: Taking the Skies [15 - 20]
- Meridian Volume 4: Coming Home [21 - 26]
The compendia collection series FORGE actually re-prints the series up until issues 30 or so.