Currently the align env is not treated properly.
this align
\begin{align} |z-z_i| <\delta_i/2,\\ |w-z_i| &= |w-z+z-z_i| \nonumber\\ &\leq |w-z| + |z-z_i| \nonumber \\ & < \delta + \delta_i/2 \nonumber\\ & \leq \delta_i/2 + \delta_i/2 \nonumber \\ &< \delta_i. \end{align}
became
\begin{align}|z-z_i| <\delta_i/2,\\ |w-z_i| &=& |w-z+z-z_i| \\ &\leqslant & |w-z| + |z-z_i| \\ & <& \delta + \delta_i/2 \\ & \leqslant & \delta_i/2 + \delta_i/2 \\ &<& \delta_i.\end{align}