While still mixing sunny ’60s surf-pop and stormy ’90s alt-rock, Best Coast has thickened up their sound throughout the years, building upon each release as they’ve moved through the last half decade. Their latest record, this year’s “California Nights,” continues the process of rounding out their sound, without trying to be overly slick in the studio or by attempting to recreate the entire equation. If anything, it’s actually darker, maintaining the feel of their minimalistic roots, with the difference of appearing more confident taking greater chances.