If \( f(t) =\displaystyle \int_{0}^{\pi} \frac{2x \, dx}{1 - \cos^{2} t \, \sin^{2} x} \), \( 0 < t < \pi \), then the value of \(\displaystyle \int_{0}^{\pi/2} \frac{\pi^{2} \, dt}{f(t)} \) equals \( \_\_\_\_\_\_ \).