For Mac OS users, there is a system setting that may not allow you to tab onto several types of elements in a web page. To change this setting:
Back, left to right: Pansy Ewell, William R. Wood, Irene Neal, Dr. J. W. Blattner, Ollie Wilkerson, Rachel Kirk.
Front, left to right: Mabel McDaniel, Grover Schenk, Nora Nanney, Cooper Clements, Ella Wilcoxson.