We construct a gauge theory based on principal bundles $\mathcal{P}$ equipped
with a right $\mathcal{G}$-action, where $\mathcal{G}$ is a Lie group bundle.
Due to the fact that a $\mathcal{G}$-action acts fibre by fibre, pushforwards
of tangent vectors via a right-translation act now only on the vertical
structure of $\mathcal{P}$. Thus, we generalize pushforwards using sections of
$\mathcal{G}$, and in order to provide a definition independent of the choice
of section we fix a connection on $\mathcal{G}$, which will modify the
pushforward by subtracting the fundamental vector field generated by a
generalized Darboux derivative of the chosen section. A horizontal distribution
on $\mathcal{P}$ invariant under such a modified pushforward leads to a
parallel transport on $\mathcal{P}$ which is a homomorphism w.r.t. the
$\mathcal{G}$-action and the parallel transport on $\mathcal{G}$. For achieving
gauge invariance we impose conditions on the connection 1-form $\mu$ on
$\mathcal{G}$: $\mu$ has to be a multiplicative form, (i.e.) closed w.r.t. a
certain simplicial differential $\delta$ on $\mathcal{G}$, and the curvature
$R_\delta$ of $\mu$ has to be $\delta$-exact with primitive $\zeta$; $\mu$ will
be the generalization of the Maurer-Cartan form of the classical gauge theory,
while the $\delta$-exactness of $R_\delta$ will generalize the role of the
Maurer-Cartan equation. For allowing curved connections on $\mathcal{G}$ we
will need to generalize the typical definition of the curvature/field strength
$F$ on $\mathcal{P}$, that is, we add $\zeta$ to $F$. This leads to a
generalized gauge theory with many similar, but generalized, statements,
including Bianchi identity, gauge transformations and Darboux derivatives. An
example for a gauge theory with a curved Maurer-Cartan form $\mu$ will be
provided by the inner group bundle of the Hopf fibration $\mathbb{S}^7 \to
\mathbb{S}^4$.
