margin-bottom: 0;\n\n    + .form-control,\n    + .custom-select,\n    + .custom-file {\n      margin-left: -$input-border-width;\n    }\n  }\n\n  // Bring the \"active\" form control to the top of surrounding elements\n  > .form-control:focus,\n  > .custom-select:focus,\n  > .custom-file .custom-file-input:focus ~ .custom-file-label {\n    z-index: 3;\n  }\n\n  // Bring the custom file input above the label\n  > .custom-file .custom-file-input:focus {\n    z-index: 4;\n  }\n\n  > .form-control,\n  > .custom-select...