Your adornment must not be merely external-- braiding the hair, and wearing gold jewelry, or putting on dresses; but let it be the hidden person of the heart, with the imperishable quality of a gentle and quiet spirit, which is precious in the sight of God. 1 Peter 3:3-4 NASB
You see the emphasis, in the scriptural discussion of modesty? While there is a component of physical dress, it's greatly overshadowed by the workings of our heart and mind. I think that holy "imbalance" is important. If you tilt too far in setting up your own standards of modesty as tests to "true Christianity" and proudly judge everyone by your own standards, attempting to shame those who dress inappropriately (whether it's categorically inappropriately or a matter of small differences), perhaps you are not following in the Word.
Old Navy 2013 - the sweet red toddler/preschooler dress is vintage-sweet and would look super cute with a pair of yellow cropped leggings underneath, and the older girl's knit maxi dress could work all year-round with proper layering.