diff --git a/.stylelintrc b/.stylelintrc
index 32fecd2..3c16391 100644
--- a/.stylelintrc
+++ b/.stylelintrc
@@ -3,6 +3,13 @@
     "stylelint-config-twbs-bootstrap/scss"
   ],
   "rules": {
-    "selector-class-pattern": "^[a-z][a-z0-9\\-_]*[a-z0-9]$"
+    "block-closing-brace-empty-line-before": "never",
+    "declaration-no-important": null,
+    "rule-empty-line-before": ["always", {
+      "except": ["first-nested"],
+      "ignore": ["after-comment"]
+    }],
+    "selector-class-pattern": "^[a-z][a-z0-9\\-_]*[a-z0-9]$",
+    "selector-no-qualifying-type": null
   }
 }
diff --git a/dist/select2-bootstrap4.css b/dist/select2-bootstrap4.css
index 4bb4db5..2ede516 100644
--- a/dist/select2-bootstrap4.css
+++ b/dist/select2-bootstrap4.css
@@ -4,9 +4,8 @@
     outline: 0; }
 
 .input-group .select2-container--bootstrap4 {
-  -webkit-box-flex: 1;
-      -ms-flex-positive: 1;
-          flex-grow: 1; }
+  -ms-flex-positive: 1;
+      flex-grow: 1; }
 
 .input-group-prepend ~ .select2-container--bootstrap4 .select2-selection {
   border-top-left-radius: 0;
@@ -18,27 +17,25 @@
 
 .select2-container--bootstrap4 .select2-selection {
   width: 100%;
+  min-height: calc(1.5em + 0.75rem + 2px);
+  padding: 0.375rem 1.75rem 0.375rem 0.75rem;
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
+  font-size: 1rem;
+  font-weight: 400;
+  line-height: 1.5;
+  color: #495057;
+  vertical-align: middle;
   background-color: #fff;
   border: 1px solid #ced4da;
   border-radius: 0.25rem;
-  -webkit-transition: border-color 0.15s ease-in-out, -webkit-box-shadow 0.15s ease-in-out;
-  transition: border-color 0.15s ease-in-out, -webkit-box-shadow 0.15s ease-in-out;
-  transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
-  transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out, -webkit-box-shadow 0.15s ease-in-out; }
+  transition: background-color 0.15s ease-in-out, border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out; }
   @media (prefers-reduced-motion: reduce) {
     .select2-container--bootstrap4 .select2-selection {
-      -webkit-transition: none;
       transition: none; } }
 
 .select2-container--bootstrap4.select2-container--focus .select2-selection {
   border-color: #80bdff;
-  -webkit-box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
-          box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25); }
-
-.select2-container--bootstrap4.select2-container--focus.select2-container--open .select2-selection {
-  border-bottom: none;
-  border-bottom-right-radius: 0;
-  border-bottom-left-radius: 0; }
+  box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25); }
 
 .select2-container--bootstrap4.select2-container--open.select2-container--above .select2-selection {
   border-top-left-radius: 0;
@@ -48,15 +45,12 @@
   border-bottom-right-radius: 0;
   border-bottom-left-radius: 0; }
 
-.select2-container--bootstrap4.select2-container--disabled .select2-selection, .select2-container--bootstrap4.select2-container--disabled.select2-container--focus .select2-selection {
+.select2-container--bootstrap4.select2-container--disabled .select2-selection,
+.select2-container--bootstrap4.select2-container--disabled .select2-search__field {
   cursor: not-allowed;
   background-color: #e9ecef;
   border-color: #ced4da;
-  -webkit-box-shadow: none;
-          box-shadow: none; }
-
-.select2-container--bootstrap4.select2-container--disabled .select2-search__field, .select2-container--bootstrap4.select2-container--disabled.select2-container--focus .select2-search__field {
-  background-color: transparent; }
+  box-shadow: none; }
 
 select.is-invalid ~ .select2-container--bootstrap4 .select2-selection,
 form.was-validated select:invalid ~ .select2-container--bootstrap4 .select2-selection {
@@ -66,36 +60,30 @@ select.is-valid ~ .select2-container--bootstrap4 .select2-selection,
 form.was-validated select:valid ~ .select2-container--bootstrap4 .select2-selection {
   border-color: #28a745; }
 
-.select2-container--bootstrap4 .select2-search {
-  width: 100%; }
-
 .select2-container--bootstrap4 .select2-dropdown {
   border-color: #ced4da;
   border-radius: 0; }
   .select2-container--bootstrap4 .select2-dropdown.select2-dropdown--below {
-    border-top: none;
     border-bottom-right-radius: 0.25rem;
     border-bottom-left-radius: 0.25rem; }
   .select2-container--bootstrap4 .select2-dropdown.select2-dropdown--above {
-    border-top: 1px solid #ced4da;
     border-top-left-radius: 0.25rem;
     border-top-right-radius: 0.25rem; }
-  .select2-container--bootstrap4 .select2-dropdown .select2-results__option[aria-selected="true"] {
-    color: #212529;
-    background-color: #f2f2f2; }
-
-.select2-container--bootstrap4 .select2-results__option--highlighted,
-.select2-container--bootstrap4 .select2-results__option--highlighted.select2-results__option[aria-selected="true"] {
-  color: #fff;
-  background-color: #007bff; }
-
-.select2-container--bootstrap4 .select2-results__option[role="group"] {
-  padding: 0; }
-  .select2-container--bootstrap4 .select2-results__option[role="group"] .select2-results__options--nested .select2-results__option {
-    padding-left: 1em; }
 
 .select2-container--bootstrap4 .select2-results__option {
   padding: 0.375rem 0.75rem; }
+  .select2-container--bootstrap4 .select2-results__option--selected {
+    color: #212529;
+    background-color: #e9ecef; }
+  .select2-container--bootstrap4 .select2-results__option--disabled {
+    color: #6c757d; }
+  .select2-container--bootstrap4 .select2-results__option--highlighted {
+    color: #fff;
+    background-color: #007bff; }
+  .select2-container--bootstrap4 .select2-results__option--group {
+    padding: 0; }
+    .select2-container--bootstrap4 .select2-results__option--group .select2-results__options--nested .select2-results__option {
+      padding-left: 0.75rem; }
 
 .select2-container--bootstrap4 .select2-results > .select2-results__options {
   max-height: 15em;
@@ -103,99 +91,96 @@ form.was-validated select:valid ~ .select2-container--bootstrap4 .select2-select
 
 .select2-container--bootstrap4 .select2-results__group {
   display: list-item;
-  padding: 6px;
+  padding: 0.375rem 0.375rem;
   color: #6c757d; }
 
 .select2-container--bootstrap4 .select2-selection__clear {
   float: right;
-  width: .9em;
-  height: .9em;
-  padding-left: .15em;
-  margin-top: .7em;
-  margin-right: .3em;
-  line-height: .75em;
-  color: #f8f9fa;
-  background-color: #c8c8c8;
+  width: 1em;
+  height: 1em;
+  padding: 0;
+  margin: 0.25em 0 0;
+  font-weight: 700;
+  line-height: 0.75em;
+  color: #495057;
+  background: #e6e6e6 url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 16 16'%3e%3cpath fill='%23495057' d='M1 12l4-4-4-4 3-3 4 4 4-4 3 3-4 4 4 4-3 3-4-4-4 4z'/%3e%3c/svg%3e") center no-repeat !important;
   border-radius: 100%; }
+  .select2-container--bootstrap4 .select2-selection__clear span {
+    display: none; }
   .select2-container--bootstrap4 .select2-selection__clear:hover {
-    background-color: #afafaf; }
+    background-color: #d9d9d9 !important; }
+
+.select2-container--bootstrap4 .select2-results__message {
+  color: #6c757d; }
 
 .select2-container--bootstrap4 .select2-selection--single {
-  height: calc(1.5em + 0.75rem + 2px) !important; }
+  background: #fff url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='4' height='5' viewBox='0 0 4 5'%3e%3cpath fill='%23343a40' d='M2 0L0 2h4zm0 5L0 3h4z'/%3e%3c/svg%3e") right 0.75rem center/8px 10px no-repeat; }
   .select2-container--bootstrap4 .select2-selection--single .select2-selection__placeholder {
-    line-height: calc(1.5em + 0.75rem);
     color: #6c757d; }
-  .select2-container--bootstrap4 .select2-selection--single .select2-selection__arrow {
-    position: absolute;
-    top: 50%;
-    right: 3px;
-    width: 20px; }
-    .select2-container--bootstrap4 .select2-selection--single .select2-selection__arrow b {
-      position: absolute;
-      top: 60%;
-      left: 50%;
-      width: 0;
-      height: 0;
-      margin-top: -2px;
-      margin-left: -4px;
-      border-color: #343a40 transparent transparent transparent;
-      border-style: solid;
-      border-width: 5px 4px 0; }
   .select2-container--bootstrap4 .select2-selection--single .select2-selection__rendered {
-    padding-left: 0.75rem;
-    line-height: calc(1.5em + 0.75rem);
+    padding: 0;
     color: #495057; }
 
-.select2-search--dropdown .select2-search__field {
+.select2-container--bootstrap4 .select2-search--dropdown .select2-search__field {
   padding: 0.375rem 0.75rem;
+  color: #495057;
   border: 1px solid #ced4da;
   border-radius: 0.25rem; }
-
-.select2-results__message {
-  color: #6c757d; }
+  .select2-container--bootstrap4 .select2-search--dropdown .select2-search__field:focus {
+    color: #495057;
+    background-color: #fff;
+    border-color: #80bdff;
+    outline: 0;
+    box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25); }
 
 .select2-container--bootstrap4 .select2-selection--multiple {
-  min-height: calc(1.5em + 0.75rem + 2px) !important; }
+  padding: 0 0.75rem; }
   .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__rendered {
-    -webkit-box-sizing: border-box;
-            box-sizing: border-box;
-    width: 100%;
-    padding: 0 0.375rem;
-    margin: 0;
-    list-style: none; }
+    margin: 0; }
+  .select2-container--bootstrap4 .select2-selection--multiple .select2-search--inline {
+    display: inline-block; }
   .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice {
-    float: left;
-    padding: 0;
-    padding-right: 0.75rem;
-    margin-top: calc(0.375rem - 2px);
-    margin-right: 0.375rem;
-    color: #495057;
+    position: relative;
+    display: inline-block;
+    padding: 0 5px 0 21px;
+    margin: 0.375rem 0.375rem 0.375rem 0;
+    color: #fff;
+    vertical-align: top;
     cursor: pointer;
-    border: 1px solid #bdc6d0;
+    background-color: #6c757d;
     border-radius: 0.2rem; }
+  .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__display {
+    padding: 0 5px; }
   .select2-container--bootstrap4 .select2-selection--multiple .select2-search__field {
+    height: calc(1.5em + 0.75rem);
+    padding-top: 0.375rem;
+    margin: 0;
+    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "Liberation Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
+    line-height: 1.5;
     color: #495057; }
-  .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice + .select2-search {
-    width: 0; }
   .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove {
-    float: left;
-    padding-right: 3px;
-    padding-left: 3px;
-    margin-right: 1px;
-    margin-left: 3px;
+    position: absolute;
+    top: 0;
+    left: 0;
+    padding: 0 5px;
+    margin: 0;
     font-weight: 700;
-    color: #bdc6d0; }
+    color: rgba(255, 255, 255, 0.75);
+    cursor: pointer;
+    background: none;
+    border: none;
+    border-right: 1px solid #a1a8ae; }
     .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove:hover {
-      color: #343a40; }
+      color: rgba(255, 255, 255, 0.85); }
+  .select2-container--bootstrap4 .select2-selection--multiple.select2-selection--clearable {
+    padding-right: 32px; }
   .select2-container--bootstrap4 .select2-selection--multiple .select2-selection__clear {
-    position: absolute !important;
-    top: 0;
-    right: .7em;
-    float: none;
-    margin-right: 0; }
+    position: absolute;
+    top: 0.375rem;
+    right: 0.75rem; }
 
 .select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice {
-  padding: 0 5px;
+  padding-left: 5px;
   cursor: not-allowed; }
   .select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice .select2-selection__choice__remove {
     display: none; }
diff --git a/dist/select2-bootstrap4.min.css b/dist/select2-bootstrap4.min.css
index 6d36591..2cb962d 100644
--- a/dist/select2-bootstrap4.min.css
+++ b/dist/select2-bootstrap4.min.css
@@ -1,2 +1,2 @@
-.select2-container{display:block}.select2-container *:focus{outline:0}.input-group .select2-container--bootstrap4{-webkit-box-flex:1;-ms-flex-positive:1;flex-grow:1}.input-group-prepend ~ .select2-container--bootstrap4 .select2-selection{border-top-left-radius:0;border-bottom-left-radius:0}.input-group>.select2-container--bootstrap4:not(:last-child) .select2-selection{border-top-right-radius:0;border-bottom-right-radius:0}.select2-container--bootstrap4 .select2-selection{width:100%;background-color:#fff;border:1px solid #ced4da;border-radius:.25rem;-webkit-transition:border-color 0.15s ease-in-out,-webkit-box-shadow 0.15s ease-in-out;transition:border-color 0.15s ease-in-out,-webkit-box-shadow 0.15s ease-in-out;transition:border-color 0.15s ease-in-out,box-shadow 0.15s ease-in-out;transition:border-color 0.15s ease-in-out,box-shadow 0.15s ease-in-out,-webkit-box-shadow 0.15s ease-in-out}@media (prefers-reduced-motion: reduce){.select2-container--bootstrap4 .select2-selection{-webkit-transition:none;transition:none}}.select2-container--bootstrap4.select2-container--focus .select2-selection{border-color:#80bdff;-webkit-box-shadow:0 0 0 .2rem rgba(0,123,255,0.25);box-shadow:0 0 0 .2rem rgba(0,123,255,0.25)}.select2-container--bootstrap4.select2-container--focus.select2-container--open .select2-selection{border-bottom:none;border-bottom-right-radius:0;border-bottom-left-radius:0}.select2-container--bootstrap4.select2-container--open.select2-container--above .select2-selection{border-top-left-radius:0;border-top-right-radius:0}.select2-container--bootstrap4.select2-container--open.select2-container--below .select2-selection{border-bottom-right-radius:0;border-bottom-left-radius:0}.select2-container--bootstrap4.select2-container--disabled .select2-selection,.select2-container--bootstrap4.select2-container--disabled.select2-container--focus .select2-selection{cursor:not-allowed;background-color:#e9ecef;border-color:#ced4da;-webkit-box-shadow:none;box-shadow:none}.select2-container--bootstrap4.select2-container--disabled .select2-search__field,.select2-container--bootstrap4.select2-container--disabled.select2-container--focus .select2-search__field{background-color:transparent}select.is-invalid ~ .select2-container--bootstrap4 .select2-selection,form.was-validated select:invalid ~ .select2-container--bootstrap4 .select2-selection{border-color:#dc3545}select.is-valid ~ .select2-container--bootstrap4 .select2-selection,form.was-validated select:valid ~ .select2-container--bootstrap4 .select2-selection{border-color:#28a745}.select2-container--bootstrap4 .select2-search{width:100%}.select2-container--bootstrap4 .select2-dropdown{border-color:#ced4da;border-radius:0}.select2-container--bootstrap4 .select2-dropdown.select2-dropdown--below{border-top:none;border-bottom-right-radius:.25rem;border-bottom-left-radius:.25rem}.select2-container--bootstrap4 .select2-dropdown.select2-dropdown--above{border-top:1px solid #ced4da;border-top-left-radius:.25rem;border-top-right-radius:.25rem}.select2-container--bootstrap4 .select2-dropdown .select2-results__option[aria-selected="true"]{color:#212529;background-color:#f2f2f2}.select2-container--bootstrap4 .select2-results__option--highlighted,.select2-container--bootstrap4 .select2-results__option--highlighted.select2-results__option[aria-selected="true"]{color:#fff;background-color:#007bff}.select2-container--bootstrap4 .select2-results__option[role="group"]{padding:0}.select2-container--bootstrap4 .select2-results__option[role="group"] .select2-results__options--nested .select2-results__option{padding-left:1em}.select2-container--bootstrap4 .select2-results__option{padding:.375rem .75rem}.select2-container--bootstrap4 .select2-results>.select2-results__options{max-height:15em;overflow-y:auto}.select2-container--bootstrap4 .select2-results__group{display:list-item;padding:6px;color:#6c757d}.select2-container--bootstrap4 .select2-selection__clear{float:right;width:.9em;height:.9em;padding-left:.15em;margin-top:.7em;margin-right:.3em;line-height:.75em;color:#f8f9fa;background-color:#c8c8c8;border-radius:100%}.select2-container--bootstrap4 .select2-selection__clear:hover{background-color:#afafaf}.select2-container--bootstrap4 .select2-selection--single{height:calc(1.5em + .75rem + 2px) !important}.select2-container--bootstrap4 .select2-selection--single .select2-selection__placeholder{line-height:calc(1.5em + .75rem);color:#6c757d}.select2-container--bootstrap4 .select2-selection--single .select2-selection__arrow{position:absolute;top:50%;right:3px;width:20px}.select2-container--bootstrap4 .select2-selection--single .select2-selection__arrow b{position:absolute;top:60%;left:50%;width:0;height:0;margin-top:-2px;margin-left:-4px;border-color:#343a40 transparent transparent transparent;border-style:solid;border-width:5px 4px 0}.select2-container--bootstrap4 .select2-selection--single .select2-selection__rendered{padding-left:.75rem;line-height:calc(1.5em + .75rem);color:#495057}.select2-search--dropdown .select2-search__field{padding:.375rem .75rem;border:1px solid #ced4da;border-radius:.25rem}.select2-results__message{color:#6c757d}.select2-container--bootstrap4 .select2-selection--multiple{min-height:calc(1.5em + .75rem + 2px) !important}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__rendered{-webkit-box-sizing:border-box;box-sizing:border-box;width:100%;padding:0 .375rem;margin:0;list-style:none}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice{float:left;padding:0;padding-right:.75rem;margin-top:calc(.375rem - 2px);margin-right:.375rem;color:#495057;cursor:pointer;border:1px solid #bdc6d0;border-radius:.2rem}.select2-container--bootstrap4 .select2-selection--multiple .select2-search__field{color:#495057}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice+.select2-search{width:0}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove{float:left;padding-right:3px;padding-left:3px;margin-right:1px;margin-left:3px;font-weight:700;color:#bdc6d0}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove:hover{color:#343a40}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__clear{position:absolute !important;top:0;right:.7em;float:none;margin-right:0}.select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice{padding:0 5px;cursor:not-allowed}.select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice .select2-selection__choice__remove{display:none}
+.select2-container{display:block}.select2-container *:focus{outline:0}.input-group .select2-container--bootstrap4{-ms-flex-positive:1;flex-grow:1}.input-group-prepend ~ .select2-container--bootstrap4 .select2-selection{border-top-left-radius:0;border-bottom-left-radius:0}.input-group>.select2-container--bootstrap4:not(:last-child) .select2-selection{border-top-right-radius:0;border-bottom-right-radius:0}.select2-container--bootstrap4 .select2-selection{width:100%;min-height:calc(1.5em + .75rem + 2px);padding:.375rem 1.75rem .375rem .75rem;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans","Liberation Sans",sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol","Noto Color Emoji";font-size:1rem;font-weight:400;line-height:1.5;color:#495057;vertical-align:middle;background-color:#fff;border:1px solid #ced4da;border-radius:.25rem;transition:background-color 0.15s ease-in-out,border-color 0.15s ease-in-out,box-shadow 0.15s ease-in-out}@media (prefers-reduced-motion: reduce){.select2-container--bootstrap4 .select2-selection{transition:none}}.select2-container--bootstrap4.select2-container--focus .select2-selection{border-color:#80bdff;box-shadow:0 0 0 .2rem rgba(0,123,255,0.25)}.select2-container--bootstrap4.select2-container--open.select2-container--above .select2-selection{border-top-left-radius:0;border-top-right-radius:0}.select2-container--bootstrap4.select2-container--open.select2-container--below .select2-selection{border-bottom-right-radius:0;border-bottom-left-radius:0}.select2-container--bootstrap4.select2-container--disabled .select2-selection,.select2-container--bootstrap4.select2-container--disabled .select2-search__field{cursor:not-allowed;background-color:#e9ecef;border-color:#ced4da;box-shadow:none}select.is-invalid ~ .select2-container--bootstrap4 .select2-selection,form.was-validated select:invalid ~ .select2-container--bootstrap4 .select2-selection{border-color:#dc3545}select.is-valid ~ .select2-container--bootstrap4 .select2-selection,form.was-validated select:valid ~ .select2-container--bootstrap4 .select2-selection{border-color:#28a745}.select2-container--bootstrap4 .select2-dropdown{border-color:#ced4da;border-radius:0}.select2-container--bootstrap4 .select2-dropdown.select2-dropdown--below{border-bottom-right-radius:.25rem;border-bottom-left-radius:.25rem}.select2-container--bootstrap4 .select2-dropdown.select2-dropdown--above{border-top-left-radius:.25rem;border-top-right-radius:.25rem}.select2-container--bootstrap4 .select2-results__option{padding:.375rem .75rem}.select2-container--bootstrap4 .select2-results__option--selected{color:#212529;background-color:#e9ecef}.select2-container--bootstrap4 .select2-results__option--disabled{color:#6c757d}.select2-container--bootstrap4 .select2-results__option--highlighted{color:#fff;background-color:#007bff}.select2-container--bootstrap4 .select2-results__option--group{padding:0}.select2-container--bootstrap4 .select2-results__option--group .select2-results__options--nested .select2-results__option{padding-left:.75rem}.select2-container--bootstrap4 .select2-results>.select2-results__options{max-height:15em;overflow-y:auto}.select2-container--bootstrap4 .select2-results__group{display:list-item;padding:.375rem .375rem;color:#6c757d}.select2-container--bootstrap4 .select2-selection__clear{float:right;width:1em;height:1em;padding:0;margin:.25em 0 0;font-weight:700;line-height:.75em;color:#495057;background:#e6e6e6 url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 16 16'%3e%3cpath fill='%23495057' d='M1 12l4-4-4-4 3-3 4 4 4-4 3 3-4 4 4 4-3 3-4-4-4 4z'/%3e%3c/svg%3e") center no-repeat !important;border-radius:100%}.select2-container--bootstrap4 .select2-selection__clear span{display:none}.select2-container--bootstrap4 .select2-selection__clear:hover{background-color:#d9d9d9 !important}.select2-container--bootstrap4 .select2-results__message{color:#6c757d}.select2-container--bootstrap4 .select2-selection--single{background:#fff url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' width='4' height='5' viewBox='0 0 4 5'%3e%3cpath fill='%23343a40' d='M2 0L0 2h4zm0 5L0 3h4z'/%3e%3c/svg%3e") right .75rem center/8px 10px no-repeat}.select2-container--bootstrap4 .select2-selection--single .select2-selection__placeholder{color:#6c757d}.select2-container--bootstrap4 .select2-selection--single .select2-selection__rendered{padding:0;color:#495057}.select2-container--bootstrap4 .select2-search--dropdown .select2-search__field{padding:.375rem .75rem;color:#495057;border:1px solid #ced4da;border-radius:.25rem}.select2-container--bootstrap4 .select2-search--dropdown .select2-search__field:focus{color:#495057;background-color:#fff;border-color:#80bdff;outline:0;box-shadow:0 0 0 .2rem rgba(0,123,255,0.25)}.select2-container--bootstrap4 .select2-selection--multiple{padding:0 .75rem}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__rendered{margin:0}.select2-container--bootstrap4 .select2-selection--multiple .select2-search--inline{display:inline-block}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice{position:relative;display:inline-block;padding:0 5px 0 21px;margin:.375rem .375rem .375rem 0;color:#fff;vertical-align:top;cursor:pointer;background-color:#6c757d;border-radius:.2rem}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__display{padding:0 5px}.select2-container--bootstrap4 .select2-selection--multiple .select2-search__field{height:calc(1.5em + .75rem);padding-top:.375rem;margin:0;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"Noto Sans","Liberation Sans",sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol","Noto Color Emoji";line-height:1.5;color:#495057}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove{position:absolute;top:0;left:0;padding:0 5px;margin:0;font-weight:700;color:rgba(255,255,255,0.75);cursor:pointer;background:none;border:none;border-right:1px solid #a1a8ae}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__choice__remove:hover{color:rgba(255,255,255,0.85)}.select2-container--bootstrap4 .select2-selection--multiple.select2-selection--clearable{padding-right:32px}.select2-container--bootstrap4 .select2-selection--multiple .select2-selection__clear{position:absolute;top:.375rem;right:.75rem}.select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice{padding-left:5px;cursor:not-allowed}.select2-container--bootstrap4.select2-container--disabled .select2-selection--multiple .select2-selection__choice .select2-selection__choice__remove{display:none}
 
diff --git a/package.json b/package.json
index bd421ed..64456e8 100644
--- a/package.json
+++ b/package.json
@@ -49,7 +49,16 @@
   },
   "jsdelivr": "dist/select2-bootstrap4.min.css",
   "browserslist": [
-    "last 2 versions",
-    "ios >= 9"
+    ">= 1%",
+    "last 1 major version",
+    "not dead",
+    "Chrome >= 45",
+    "Firefox >= 38",
+    "Edge >= 12",
+    "Explorer >= 10",
+    "iOS >= 9",
+    "Safari >= 9",
+    "Android >= 4.4",
+    "Opera >= 30"
   ]
 }
diff --git a/src/_layout.scss b/src/_layout.scss
index 1c33c41..f04897e 100644
--- a/src/_layout.scss
+++ b/src/_layout.scss
@@ -1,3 +1,11 @@
+$s2bs4-selection-clear-icon: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' width='10' height='10' viewBox='0 0 16 16'><path fill='#{$custom-select-color}' d='M1 12l4-4-4-4 3-3 4 4 4-4 3 3-4 4 4 4-3 3-4-4-4 4z'/></svg>") !default;
+
+// `font-family` fallback. This is needed because `$custom-select-font-family`
+// defaults to null, but this theme needs an existing value to override
+// Select2's `font-family: sans-serif` rule
+$s2bs4-font-family: $custom-select-font-family !default;
+$s2bs4-font-family: $font-family-base !default;
+
 // basic
 .select2-container {
   display: block;
@@ -11,11 +19,13 @@
 .input-group .select2-container--bootstrap4 {
   flex-grow: 1;
 }
+
 // for prepended input
 .input-group-prepend ~ .select2-container--bootstrap4 .select2-selection {
   border-top-left-radius: 0;
   border-bottom-left-radius: 0;
 }
+
 // for appended input
 .input-group > .select2-container--bootstrap4:not(:last-child) .select2-selection {
   border-top-right-radius: 0;
@@ -23,38 +33,38 @@
 }
 
 .select2-container--bootstrap4 {
-
   // input box
   .select2-selection {
     width: 100%;
-    background-color: $input-bg;
-    border: $input-border-width solid $input-border-color;
-    @include border-radius($input-border-radius);
-    @include box-shadow($input-box-shadow);
-    @include transition($input-transition);
+    min-height: $custom-select-height;
+    padding: $custom-select-padding-y ($custom-select-padding-x + $custom-select-indicator-padding) $custom-select-padding-y $custom-select-padding-x;
+    font-family: $s2bs4-font-family;
+    @include font-size($custom-select-font-size);
+    font-weight: $custom-select-font-weight;
+    line-height: $custom-select-line-height;
+    color: $custom-select-color;
+    vertical-align: middle;
+    background-color: $custom-select-bg;
+    border: $custom-select-border-width solid $custom-select-border-color;
+    @include border-radius($custom-select-border-radius, 0);
+    @include box-shadow($custom-select-box-shadow);
+    @include transition($custom-forms-transition);
   }
 
-  // focused input box
   &.select2-container--focus {
     .select2-selection {
-      border-color: $input-focus-border-color;
-      box-shadow: $input-focus-box-shadow;
-    }
-
-    // when open, hide bottom border
-    &.select2-container--open .select2-selection {
-      border-bottom: none;
-      @include border-bottom-radius(0);
+      border-color: $custom-select-focus-border-color;
+      box-shadow: $custom-select-focus-box-shadow;
     }
   }
 
-  // open input box
   &.select2-container--open {
     &.select2-container--above {
       .select2-selection {
         @include border-top-radius(0);
       }
     }
+
     &.select2-container--below {
       .select2-selection {
         @include border-bottom-radius(0);
@@ -62,18 +72,14 @@
     }
   }
 
-  // disabled input box
-  &.select2-container--disabled,
-  &.select2-container--disabled.select2-container--focus {
-    .select2-selection {
+  &.select2-container--disabled {
+    .select2-selection,
+    .select2-search__field {
       cursor: not-allowed;
-      background-color: $input-disabled-bg;
-      border-color: $input-border-color;
+      background-color: $custom-select-disabled-bg;
+      border-color: $custom-select-border-color;
       box-shadow: none;
     }
-    .select2-search__field {
-      background-color: transparent;
-    }
   }
 
   // validated input box
@@ -82,61 +88,54 @@
   form.was-validated select:invalid ~ & .select2-selection {
     border-color: $danger;
   }
+
   select.is-valid ~ & .select2-selection,
   form.was-validated select:valid ~ & .select2-selection {
     border-color: $success;
   }
   // stylelint-enable selector-no-qualifying-type
 
-  // fixes placeholder width
-  .select2-search {
-    width: 100%;
-  }
-
-  // dropdown
   .select2-dropdown {
-    border-color: $input-border-color;
-    border-radius: 0; // overwrite select2.css
+    border-color: $custom-select-border-color;
+    border-radius: 0; // overload select2.css
 
-    // dropdown opened below
     &.select2-dropdown--below {
-      border-top: none;
-      @include border-bottom-radius($input-border-radius);
+      @include border-bottom-radius($custom-select-border-radius);
     }
 
-    // dropdown opened above
     &.select2-dropdown--above {
-      border-top: 1px solid $input-border-color;
-      @include border-top-radius($input-border-radius);
+      @include border-top-radius($custom-select-border-radius);
     }
+  }
 
-    // selected item
-    .select2-results__option[aria-selected="true"] {
-      color: color-yiq(darken($input-bg, 5%));
-      background-color: darken($input-bg, 5%);
+  .select2-results__option {
+    padding: $custom-select-padding-y $custom-select-padding-x;
+
+    &--selected {
+      color: color-yiq($custom-select-disabled-bg);
+      background-color: $custom-select-disabled-bg;
     }
-  }
 
-  // mouse hovered item
-  .select2-results__option--highlighted,
-  .select2-results__option--highlighted.select2-results__option[aria-selected="true"] {
-    color: color-yiq($primary);
-    background-color: $primary;
-  }
+    &--disabled {
+      color: $custom-select-disabled-color;
+    }
 
-  // for <optgroup>
-  .select2-results__option[role="group"] {
-    padding: 0;
-    .select2-results__options--nested .select2-results__option {
-      padding-left: 1em;
+    // hover
+    &--highlighted {
+      color: color-yiq($primary);
+      background-color: $primary;
     }
-  }
 
-  .select2-results__option {
-    padding: $input-padding-y $input-padding-x;
+    &--group {
+      padding: 0;
+
+      .select2-results__options--nested .select2-results__option {
+        padding-left: $custom-select-padding-x;
+      }
+    }
   }
 
-  // fixes vertical overflow
+  // vertical overflow
   .select2-results > .select2-results__options {
     max-height: 15em;
     overflow-y: auto;
@@ -144,25 +143,35 @@
 
   .select2-results__group {
     display: list-item;
-    padding: 6px;
+    padding: $custom-select-padding-y $custom-select-padding-x / 2;
     color: $secondary;
   }
 
-  // all clear button
+  // clear all button
   .select2-selection__clear {
-    $bg: #c8c8c8;
     float: right;
-    width: .9em;
-    height: .9em;
-    padding-left: .15em;
-    margin-top: .7em;
-    margin-right: .3em;
-    line-height: .75em;
-    color: $light;
-    background-color: $bg;
+    width: 1em;
+    height: 1em;
+    padding: 0;
+    margin: subtract($custom-select-line-height * 1em, 1em) / 2 0 0;
+    font-weight: 700;
+    line-height: (12em / 16);
+    color: $custom-select-color;
+    background: darken($custom-select-bg, 10%) escape-svg($s2bs4-selection-clear-icon) center no-repeat !important; // stylelint-disable-line declaration-no-important
     border-radius: 100%;
+
+    // hide default &times; entity
+    span {
+      display: none;
+    }
+
     &:hover {
-      background-color: darken($bg, 10%);
+      background-color: darken($custom-select-bg, 15%) !important; // stylelint-disable-line declaration-no-important
     }
   }
+
+  // no results message
+  .select2-results__message {
+    color: $text-muted;
+  }
 }
diff --git a/src/_multiple.scss b/src/_multiple.scss
index 6531c67..01d5925 100644
--- a/src/_multiple.scss
+++ b/src/_multiple.scss
@@ -1,63 +1,71 @@
+$s2bs4-selection-choice-bg: $secondary !default;
+
 .select2-container--bootstrap4 {
   .select2-selection--multiple {
-
-    // height of input box
-    min-height: $input-height !important; // stylelint-disable-line declaration-no-important
+    padding: 0 $custom-select-padding-x;
 
     // input box
     .select2-selection__rendered {
-      box-sizing: border-box;
-      width: 100%;
-      padding: 0 $input-padding-x / 2;
       margin: 0;
-      list-style: none;
+    }
+
+    .select2-search--inline {
+      display: inline-block;
     }
 
     // each selected item in input box
     .select2-selection__choice {
-      float: left;
-      padding: 0;
-      padding-right: $input-padding-x;
-      margin-top: calc(#{$input-padding-y} - 2px);
-      margin-right: $input-padding-x / 2;
-      color: $input-color;
+      position: relative;
+      display: inline-block;
+      padding: 0 5px 0 21px;
+      margin: $custom-select-padding-y $custom-select-padding-x / 2 $custom-select-padding-y 0;
+      color: color-yiq($s2bs4-selection-choice-bg);
+      vertical-align: top;
       cursor: pointer;
-      border: 1px solid darken($light, 20%);
-      @include border-radius($input-border-radius-sm);
+      background-color: $s2bs4-selection-choice-bg;
+      @include border-radius($border-radius-sm);
     }
 
-    // search field
-    .select2-search__field {
-      color: $input-color;
+    .select2-selection__choice__display {
+      padding: 0 5px;
     }
 
-    // fixes placeholder width
-    .select2-selection__choice + .select2-search {
-      width: 0;
+    .select2-search__field {
+      height: add($custom-select-line-height * 1em, $custom-select-padding-y * 2);
+      padding-top: $custom-select-padding-y;
+      margin: 0;
+      font-family: $s2bs4-font-family;
+      line-height: $custom-select-line-height;
+      color: $custom-select-color;
     }
 
     // x button of each selected item in input box
     .select2-selection__choice__remove {
-      float: left;
-      padding-right: 3px;
-      padding-left: 3px;
-      margin-right: 1px;
-      margin-left: 3px;
+      position: absolute;
+      top: 0;
+      left: 0;
+      padding: 0 5px;
+      margin: 0;
       font-weight: 700;
-      color: darken($light, 20%);
+      color: fade-out(color-yiq($s2bs4-selection-choice-bg), .25);
+      cursor: pointer;
+      background: none;
+      border: none;
+      border-right: 1px solid lighten($s2bs4-selection-choice-bg, 20%);
+
       &:hover {
-        color: $dark;
+        color: fade-out(color-yiq($s2bs4-selection-choice-bg), .15);
       }
     }
 
-    // all clear button
+    &.select2-selection--clearable {
+      padding-right: 32px;
+    }
+
     .select2-selection__clear {
-      position: absolute !important; // stylelint-disable-line declaration-no-important
-      top: 0;
-      right: .7em;
-      // overwrite layout.scss
-      float: none;
-      margin-right: 0;
+      position: absolute;
+      top: $custom-select-padding-y;
+      right: $custom-select-padding-x;
     }
   }
 
@@ -65,7 +73,7 @@
   &.select2-container--disabled {
     .select2-selection--multiple {
       .select2-selection__choice {
-        padding: 0 5px;
+        padding-left: 5px;
         cursor: not-allowed;
         // stylelint-disable selector-max-class
         .select2-selection__choice__remove {
diff --git a/src/_single.scss b/src/_single.scss
index 9e040b9..8395bb0 100644
--- a/src/_single.scss
+++ b/src/_single.scss
@@ -1,52 +1,26 @@
 .select2-container--bootstrap4 {
   .select2-selection--single {
+    background: $custom-select-bg $custom-select-background;
 
-    // height of input box
-    height: $input-height !important; // stylelint-disable-line declaration-no-important
-
-    // placeholder
     .select2-selection__placeholder {
-      line-height: $input-height-inner;
       color: $input-placeholder-color;
     }
 
-    // arrow
-    .select2-selection__arrow {
-      position: absolute;
-      top: 50%;
-      right: 3px;
-      width: 20px;
-      b {
-        position: absolute;
-        top: 60%;
-        left: 50%;
-        width: 0;
-        height: 0;
-        margin-top: -2px;
-        margin-left: -4px;
-        border-color: $dark transparent transparent transparent;
-        border-style: solid;
-        border-width: 5px 4px 0;
-      }
-    }
-
     // selected item
     .select2-selection__rendered {
-      padding-left: $input-padding-x;
-      line-height: $input-height-inner;
-      color: $input-color;
+      padding: 0;
+      color: $custom-select-color;
     }
   }
-}
 
-// search box
-.select2-search--dropdown .select2-search__field {
-  padding: $input-padding-y $input-padding-x;
-  border: $input-border-width solid $input-border-color;
-  @include border-radius($input-border-radius);
-}
-
-// no result message
-.select2-results__message {
-  color: $secondary;
+  // search box
+  .select2-search--dropdown {
+    .select2-search__field {
+      padding: $custom-select-padding-y $custom-select-padding-x;
+      color: $custom-select-color;
+      border: $custom-select-border-width solid $custom-select-border-color;
+      @include border-radius($custom-select-border-radius);
+      @include form-control-focus(true);
+    }
+  }
 }