HTML for each, dedicated prepend and\n// append elements allow us to 1) be less clever, 2) simplify our selectors, and\n// 3) support HTML5 form validation.\n\n.input-group-prepend,\n.input-group-append {\n  display: flex;\n\n  // Ensure buttons are always above inputs for more visually pleasing borders.\n  // This isn't needed for `.input-group-text` since it shares the same border-color\n  // as our inputs.\n  .btn {\n    position: relative;\n    z-index: 2;\n\n    &:focus {\n      z-index: 3;\n...