.form-control-plaintext,\n  > .custom-select,\n  > .custom-file {\n    position: relative; // For focus state's z-index\n    flex: 1 1 auto;\n    width: 1%;\n    min-width: 0; // https://stackoverflow.com/questions/36247140/why-dont-flex-items-shrink-past-content-size\n    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...