diff --git a/less/admin/AdminNav.less b/less/admin/AdminNav.less
index 74978fe60f..e186ea4cf7 100644
--- a/less/admin/AdminNav.less
+++ b/less/admin/AdminNav.less
@@ -52,12 +52,20 @@
 }
 
 @media @phone, @tablet {
-  .AdminNav {
+  .App-nav .AdminNav {
     .Dropdown-menu {
       > li {
+        .ExtensionListTitle {
+          color: @muted-color;
+          text-transform: uppercase;
+          margin: 25px 0 10px 15px;
+        }
+
         .ExtensionIcon {
           margin: -2px -29px;
-          --size: 25px;
+          width: 25px;
+          height: 25px;
+          font-size: 12.5px;
 
           .icon {
             margin: 0;
@@ -75,7 +83,7 @@
     top: @header-height;
     height: ~"calc(100vh - @{header-height})";
     width: @admin-pane-width;
-    box-shadow: 0 6px 6px @shadow-color;
+    .box-shadow(0 6px 6px @shadow-color);
     background: @body-bg;
     z-index: @zindex-pane;
     overflow-y: scroll;
@@ -149,9 +157,18 @@
           margin: 0 auto;
         }
 
+        .ExtensionListTitle {
+          color: @muted-color;
+          text-transform: uppercase;
+          margin: 25px 0 8px 15px;
+        }
+
         .ExtensionIcon {
-          --size: 25px;
+          width: 25px;
+          height: 25px;
+          font-size: 15px;
           margin-left: -29px;
+          vertical-align: middle;
         }
       }
     }
@@ -176,12 +193,6 @@
   padding-left: 5px;
 }
 
-.ExtensionListTitle {
-  color: @muted-color;
-  text-transform: uppercase;
-  margin: 25px 0 8px 15px;
-}
-
 .ExtensionListItem-Dot {
   height: 10px;
   width: 10px;
diff --git a/less/admin/ExtensionPage.less b/less/admin/ExtensionPage.less
index 5c10862b08..bed00c8a3b 100644
--- a/less/admin/ExtensionPage.less
+++ b/less/admin/ExtensionPage.less
@@ -1,5 +1,13 @@
 .ExtensionPage {
+
   &-header {
+    .ExtensionTitle {
+      display: flex;
+      align-items: center;
+      flex-wrap: wrap;
+      margin: 20px 0 15px;
+    }
+
     .helpText {
       margin-bottom: 5px;
     }
@@ -71,8 +79,11 @@
     }
 
     .ExtensionIcon {
-      --size: 30px;
+      width: 30px;
+      height: 30px;
+      font-size: 15px;
       margin-left: 0;
+      vertical-align: middle;
     }
 
     &TopItems {
@@ -112,6 +123,7 @@
   }
 
   &-permissions {
+
     .PermissionGrid-removeScope {
       display: none;
     }
@@ -128,13 +140,6 @@
   }
 }
 
-.ExtensionTitle {
-  display: flex;
-  align-items: center;
-  flex-wrap: wrap;
-  margin: 20px 0 15px;
-}
-
 .ExtensionInfo {
   margin-left: auto;
 
diff --git a/less/admin/ExtensionWidget.less b/less/admin/ExtensionWidget.less
index 3f5413d6b6..d3cfd9789f 100644
--- a/less/admin/ExtensionWidget.less
+++ b/less/admin/ExtensionWidget.less
@@ -77,14 +77,13 @@
 }
 
 .ExtensionIcon {
-  --size: 90px;
-  width: var(--size);
-  height: var(--size);
+  width: 90px;
+  height: 90px;
   background: @control-bg;
   color: @control-color;
   border-radius: 6px;
   display: inline-flex;
-  font-size: calc(~"var(--size) / 2");
+  font-size: 45px;
   text-align: center;
   align-items: center;
   justify-content: center;
diff --git a/less/admin/PermissionsPage.less b/less/admin/PermissionsPage.less
index 39ba8047e7..7f9f4c130a 100644
--- a/less/admin/PermissionsPage.less
+++ b/less/admin/PermissionsPage.less
@@ -114,7 +114,7 @@
       display: none;
     }
     .open .Dropdown-toggle {
-      box-shadow: none;
+      .box-shadow(none);
     }
   }
 }
@@ -128,7 +128,7 @@
   }
   .Badge {
     margin: -3px 3px -3px 0;
-    box-shadow: none;
+    .box-shadow(none);
   }
 }
 .PermissionGrid-section {
diff --git a/less/common/Alert.less b/less/common/Alert.less
index 72db46e62b..05495106f5 100644
--- a/less/common/Alert.less
+++ b/less/common/Alert.less
@@ -3,20 +3,6 @@
   border-radius: @border-radius;
   line-height: 1.5;
 
-  background: var(--alert-bg);
-
-  &,
-  a,
-  a:hover,
-  .Button,
-  .Button:hover,
-  .Button:active,
-  .Button.active,
-  .Button:focus,
-  .Button.focus {
-    color: var(--alert-color);
-  }
-
   .Alert--color(@alert-color, @alert-bg);
 }
 .Alert--error {
@@ -30,8 +16,19 @@
   }
 }
 .Alert--color(@color; @background) {
-  --alert-bg: @background;
-  --alert-color: @color;
+  background: @background;
+
+  &,
+  a,
+  a:hover,
+  .Button,
+  .Button:hover,
+  .Button:active,
+  .Button.active,
+  .Button:focus,
+  .Button.focus {
+    color: @color;
+  }
 }
 .Alert-controls {
   list-style-type: none;
diff --git a/less/common/AlertManager.less b/less/common/AlertManager.less
index d362e06cd1..854a0b584f 100644
--- a/less/common/AlertManager.less
+++ b/less/common/AlertManager.less
@@ -7,6 +7,6 @@
   .Alert {
     display: inline-block;
     margin-top: 20px;
-    box-shadow: 0 2px 6px @shadow-color;
+    .box-shadow(0 2px 6px @shadow-color);
   }
 }
diff --git a/less/common/App.less b/less/common/App.less
index bf9cd05127..7acd8cd75e 100644
--- a/less/common/App.less
+++ b/less/common/App.less
@@ -24,7 +24,7 @@
     }
 
     .scrolled & {
-      box-shadow: 0 2px 6px @shadow-color;
+      .box-shadow(0 2px 6px @shadow-color);
     }
   }
   .App-primaryControl, .App-titleControl, .App-backControl {
@@ -40,7 +40,7 @@
     > .Button {
       float: none;
       background: transparent !important;
-      box-shadow: none !important;
+      .box-shadow(~"none !important");
       height: @header-height-phone;
       width: auto;
       padding: 13px !important;
@@ -136,9 +136,9 @@
     left: 0;
     top: 0;
     bottom: 0;
-    box-shadow: 0 2px 6px @shadow-color;
-    transform: translate(-@drawer-width - 6px, 0);
-    transition: transform 0.2s;
+    .box-shadow(0 2px 6px @shadow-color);
+    .translate3d(-@drawer-width - 6px, 0, 0);
+    .transition-transform(0.2s);
     z-index: @zindex-modal;
 
     .drawerOpen & {
@@ -155,7 +155,7 @@
     z-index: @zindex-modal-background;
     background-color: @overlay-bg;
     opacity: 0;
-    transition: opacity 0.2s;
+    .transition(0.2s opacity);
 
     &.in {
       opacity: 0.9;
@@ -241,7 +241,7 @@
     }
 
     .scrolled & {
-      box-shadow: 0 2px 6px @shadow-color;
+      .box-shadow(0 2px 6px @shadow-color);
     }
 
     & when (@config-colored-header = true) {
diff --git a/less/common/Avatar.less b/less/common/Avatar.less
index 520c641f2c..5df0db6bf0 100644
--- a/less/common/Avatar.less
+++ b/less/common/Avatar.less
@@ -1,17 +1,12 @@
 .Avatar {
-  display: inline-flex;
-  align-items: center;
-  justify-content: center;
+  display: inline-block;
   box-sizing: content-box;
   color: #fff;
+  text-align: center;
   vertical-align: top;
   background-color: var(--avatar-bg);
   font-weight: normal;
   .Avatar--size(48px);
-  width: var(--size);
-  height: var(--size);
-  border-radius: 100%;
-  font-size: calc(~"var(--size) / 2");
 
   img {
     display: inline-block;
@@ -23,5 +18,9 @@
 }
 
 .Avatar--size(@size) {
-  --size: @size;
+  width: @size;
+  height: @size;
+  border-radius: @size;
+  font-size: @size / 2;
+  line-height: @size;
 }
diff --git a/less/common/Badge.less b/less/common/Badge.less
index 5d94cb282b..a43c97baab 100644
--- a/less/common/Badge.less
+++ b/less/common/Badge.less
@@ -1,27 +1,26 @@
 .Badge {
   .Badge--size(22px);
-  width: var(--size);
-  height: var(--size);
-  border-radius: calc(~"var(--size) / 2");
   background: var(--badge-bg);
   color: var(--badge-color);
-  display: inline-flex;
-  align-items: center;
-  justify-content: center;
+  display: inline-block;
   vertical-align: middle;
-  box-shadow: 0 2px 4px @shadow-color;
+  text-align: center;
+  .box-shadow(0 2px 4px @shadow-color);
 
   .Badge-label {
     display: none;
   }
-
-  &, .Badge-icon {
-    font-size: calc(~"0.56 * var(--size)");
-  }
 }
 
 .Badge--size(@size) {
-  --size: @size;
+  width: @size;
+  height: @size;
+  border-radius: @size / 2;
+  line-height: @size - 1px;
+
+  &, .Badge-icon {
+    font-size: 0.56 * @size;
+  }
 }
 
 .badges {
diff --git a/less/common/Button.less b/less/common/Button.less
index 3165f9af4b..438c55e3ca 100644
--- a/less/common/Button.less
+++ b/less/common/Button.less
@@ -71,7 +71,7 @@
   fieldset[disabled] & {
     cursor: default;
     opacity: 0.65;
-    box-shadow: none;
+    .box-shadow(none);
   }
 
   a& {
@@ -82,7 +82,7 @@
   }
 
   .Button-label {
-    transition: margin-right 0.1s;
+    .transition(margin-right 0.1s);
   }
 
   .LoadingIndicator-container {
@@ -142,7 +142,7 @@
   &.focus,
   .open > &.Dropdown-toggle {
     background: transparent !important;
-    box-shadow: none;
+    .box-shadow(none);
     color: @link-color;
   }
 }
@@ -158,7 +158,7 @@
   &:active,
   &.active,
   .open > &.Dropdown-toggle {
-    box-shadow: none;
+    .box-shadow(none);
   }
 }
 .Button--primary {
diff --git a/less/common/Checkbox.less b/less/common/Checkbox.less
index ce9d322b72..7826e28c53 100644
--- a/less/common/Checkbox.less
+++ b/less/common/Checkbox.less
@@ -49,7 +49,7 @@
   position: relative;
   border-radius: 14px;
   background: @control-bg;
-  transition: background-color 0.2s;
+  .transition(background-color 0.2s);
 
   .LoadingIndicator {
     --size: 22px !important;
@@ -81,7 +81,7 @@
     height: 22px;
     padding: 0;
     left: 3px;
-    transition: opacity 0.2s, left 0.2s;
+    .transition(~"opacity 0.2s, left 0.2s");
 
     .on& {
       left: 25px;
diff --git a/less/common/Dropdown.less b/less/common/Dropdown.less
index f94851226a..97c9d90736 100644
--- a/less/common/Dropdown.less
+++ b/less/common/Dropdown.less
@@ -12,7 +12,7 @@
   margin: 7px 0;
   background: @body-bg;
   border-radius: @border-radius;
-  box-shadow: 0 2px 6px @shadow-color;
+  .box-shadow(0 2px 6px @shadow-color);
   list-style: none;
   text-align: left;
   color: @text-color;
@@ -35,12 +35,11 @@
       white-space: nowrap;
       overflow: hidden;
       text-overflow: ellipsis;
-      box-shadow: none;
+      .box-shadow(none);
       text-align: left;
       font-size: 13px;
       font-weight: normal;
       text-decoration: none;
-      cursor: pointer;
 
       &.hasIcon {
         padding-left: 40px;
@@ -152,7 +151,7 @@
     float: none;
     position: static;
     background: none;
-    box-shadow: none;
+    .box-shadow(none);
   }
 }
 
@@ -174,12 +173,12 @@
     display: block;
     max-height: 70vh;
     border-radius: 0;
-    box-shadow: 0 2px 6px @shadow-color;
+    .box-shadow(0 2px 6px @shadow-color);
     visibility: hidden;
     overflow: auto;
     -webkit-overflow-scrolling: touch;
-    transform: translate(0, 70vh);
-    transition: transform 0.3s, visibility 0s 0.3s;
+    .translate3d(0, 70vh, 0);
+    .transition-transform(~" 0.3s, visibility 0s 0.3s");
 
     > li {
       > a, > button {
@@ -220,8 +219,8 @@
   .dropdown-backdrop {
     background: fade(@secondary-color, 90%);
     opacity: 0;
-    transition: opacity 0.3s;
-    transform: translate(0, 0);
+    .transition(~"opacity 0.3s");
+    .translate3d(0, 0, 0);
 
     .open & {
       opacity: 1;
diff --git a/less/common/FormControl.less b/less/common/FormControl.less
index 20f99f1f3d..9c1d1167f3 100644
--- a/less/common/FormControl.less
+++ b/less/common/FormControl.less
@@ -1,5 +1,4 @@
 .FormControl {
-  --transition: border-color .15s, background .15s;
   display: block;
   width: 100%;
   height: 36px;
@@ -10,7 +9,7 @@
   background-color: @control-bg;
   border: 2px solid transparent;
   border-radius: @border-radius;
-  transition: var(--transition);
+  .transition(~"border-color .15s, background .15s");
   -webkit-appearance: none;
 
   &:focus {
diff --git a/less/common/LoadingIndicator.less b/less/common/LoadingIndicator.less
index 96fa2d980e..4bd88188a1 100644
--- a/less/common/LoadingIndicator.less
+++ b/less/common/LoadingIndicator.less
@@ -2,7 +2,7 @@
 // Loading Indicators
 
 .LoadingIndicator {
-  --spin-time: 750ms;
+  @spin-time: 750ms;
 
   // Use the value of `color` to maintain backwards compatibility
   border-color: currentColor;
@@ -14,7 +14,7 @@
   width: var(--size);
   height: var(--size);
 
-  animation: spin var(--spin-time) linear infinite;
+  animation: spin @spin-time linear infinite;
 
   // <div> container around the spinner
   // Used for positioning
diff --git a/less/common/Modal.less b/less/common/Modal.less
index 0fdff8ee85..b2062e2a20 100644
--- a/less/common/Modal.less
+++ b/less/common/Modal.less
@@ -16,7 +16,7 @@
   z-index: @zindex-modal-background;
   background-color: @overlay-bg;
   opacity: 0;
-  transition: opacity 0.2s;
+  .transition(0.2s opacity);
 
   &.in {
     opacity: 1;
@@ -37,11 +37,11 @@
 
   // When fading in the modal, animate it to slide down
   .Modal {
-    transform: scale(0.9);
-    transition: transform 0.2s ease-out;
+    .scale(0.9);
+    .transition-transform(0.2s ease-out);
   }
   &.in .Modal {
-    transform: scale(1);
+    .scale(1);
   }
 }
 .modal-open .ModalManager {
@@ -126,7 +126,7 @@
   opacity: 0;
   pointer-events: none;
   border-radius: @border-radius;
-  transition: opacity 0.2s;
+  .transition(opacity 0.2s);
 
   &.active {
     opacity: 1;
@@ -146,8 +146,8 @@
     bottom: 0;
     top: 0;
     overflow: auto;
-    transition: transform 0.2s ease-out;
-    transform: translate(0, 100vh);
+    .transition-transform(0.2s);
+    .translate3d(0, 100vh, 0);
 
     &.in {
       -webkit-transform: none !important;
@@ -170,7 +170,7 @@
     border: 0;
     min-height: 100vh;
     padding-top: @header-height-phone;
-    box-shadow: none;
+    .box-shadow(none);
   }
   .Modal-header {
     padding: 0;
@@ -193,7 +193,7 @@
 
     border: 0;
     border-radius: @border-radius;
-    box-shadow: 0 7px 15px @shadow-color;
+    .box-shadow(0 7px 15px @shadow-color);
   }
   .Modal--small {
     max-width: 375px;
diff --git a/less/common/Navigation.less b/less/common/Navigation.less
index c50cb1d403..ca29ed68a9 100644
--- a/less/common/Navigation.less
+++ b/less/common/Navigation.less
@@ -1,7 +1,7 @@
 .Navigation-back {
   z-index: 3 !important; // z-index of an active .btn-group .btn is 2
   border-radius: @border-radius !important;
-  transition: border-radius 0.2s;
+  .transition(border-radius 0.2s);
   max-width: 150px;
   overflow: hidden;
   text-overflow: ellipsis;
@@ -17,10 +17,10 @@
   opacity: 0;
   margin-left: -5px !important;
   border-radius: 0 @border-radius @border-radius 0;
-  transition: opacity 0.2s, margin-left 0.2s;
+  .transition(~"opacity 0.2s, margin-left 0.2s");
 
   .icon {
-    transform: rotate(45deg);
+    .rotate(45deg);
   }
 }
 
@@ -38,7 +38,7 @@
     }
   }
   .hasPane.panePinned .Navigation-pin .icon {
-    transform: rotate(0);
+    .rotate(0deg);
   }
 }
 
diff --git a/less/common/Search.less b/less/common/Search.less
index 42bf633caf..cb819b3321 100644
--- a/less/common/Search.less
+++ b/less/common/Search.less
@@ -14,7 +14,7 @@
 }
 @media @tablet-up {
   .Search {
-    transition: margin-left 0.4s;
+    .transition(margin-left 0.4s);
 
     &.focused {
       margin-left: -400px;
@@ -70,7 +70,7 @@
     width: 225px;
     padding-left: 32px;
     padding-right: 32px;
-    transition: var(--transition), width 0.4s;
+    .transition(all 0.4s);
     box-sizing: inherit !important;
   }
 
diff --git a/less/common/Tooltip.less b/less/common/Tooltip.less
index 08ac8d498c..282c357363 100644
--- a/less/common/Tooltip.less
+++ b/less/common/Tooltip.less
@@ -10,7 +10,7 @@
   font-weight: normal;
   line-height: 1.4;
   opacity: 0;
-  transition: opacity 0.15s linear;
+  .transition(0.15s opacity linear);
 
   &.in     { opacity: 1; }
   &.top    { margin-top:  -3px; padding: @tooltip-arrow-width 0; }
diff --git a/less/common/mixins/header-background.less b/less/common/mixins/header-background.less
index 74d98c606e..922b4b891d 100644
--- a/less/common/mixins/header-background.less
+++ b/less/common/mixins/header-background.less
@@ -6,7 +6,7 @@
   right: 0;
   z-index: @zindex-header;
   border-bottom: 1px solid @control-bg;
-  transition: box-shadow 0.2s, transform 0.2s;
+  .transition(~"box-shadow 0.2s, -webkit-transform 0.2s");
 
   @media @phone {
     height: @header-height-phone;
diff --git a/less/common/mixins/vendor-prefixes.less b/less/common/mixins/vendor-prefixes.less
index 6286204d51..80739da302 100644
--- a/less/common/mixins/vendor-prefixes.less
+++ b/less/common/mixins/vendor-prefixes.less
@@ -6,34 +6,27 @@
 
 // Animations
 // These remain for backwards compatibility with existing styles.
-/** @deprecated */
 .animation(@animation) {
   animation: @animation;
 }
-/** @deprecated */
 .animation-name(@name) {
   animation-name: @name;
 }
 .animation-duration(@duration) {
   animation-duration: @duration;
 }
-/** @deprecated */
 .animation-timing-function(@timing-function) {
   animation-timing-function: @timing-function;
 }
-/** @deprecated */
 .animation-delay(@delay) {
   animation-delay: @delay;
 }
-/** @deprecated */
 .animation-iteration-count(@iteration-count) {
   animation-iteration-count: @iteration-count;
 }
-/** @deprecated */
 .animation-direction(@direction) {
   animation-direction: @direction;
 }
-/** @deprecated */
 .animation-fill-mode(@fill-mode) {
   animation-fill-mode: @fill-mode;
 }
@@ -41,7 +34,6 @@
 // Backface visibility
 // Prevent browsers from flickering when using CSS 3D transforms.
 // Default value is `visible`, but can be changed to `hidden`
-/** @deprecated */
 .backface-visibility(@visibility) {
   // Safari
   -webkit-backface-visibility: @visibility;
@@ -50,20 +42,17 @@
 
 // Drop shadows
 // These remain for backwards compatibility with existing styles.
-/** @deprecated */
 .box-shadow(@shadow) {
   box-shadow: @shadow;
 }
 
 // Box sizing
 // These remain for backwards compatibility with existing styles.
-/** @deprecated */
 .box-sizing(@boxmodel) {
   box-sizing: @boxmodel;
 }
 
 // CSS3 Content Columns
-/** @deprecated */
 .content-columns(@column-count; @column-gap: @grid-gutter-width) {
   // Safari
   -webkit-column-count: @column-count;
@@ -74,7 +63,6 @@
 }
 
 // Optional hyphenation
-/** @deprecated */
 .hyphens(@mode: auto) {
   word-wrap: break-word;
   // Safari
@@ -93,82 +81,63 @@
 
 // Transformations
 // These remain for backwards compatibility with existing styles.
-/** @deprecated */
 .scale(@ratio) {
   transform: scale(@ratio);
 }
-/** @deprecated */
 .scale(@ratioX; @ratioY) {
   transform: scale(@ratioX, @ratioY);
 }
-/** @deprecated */
 .scaleX(@ratio) {
   transform: scaleX(@ratio);
 }
-/** @deprecated */
 .scaleY(@ratio) {
   transform: scaleY(@ratio);
 }
-/** @deprecated */
 .skew(@x; @y) {
   transform: skewX(@x) skewY(@y);
 }
-/** @deprecated */
 .translate(@x; @y) {
   transform: translate(@x, @y);
 }
-/** @deprecated */
 .translate3d(@x; @y; @z) {
   transform: translate3d(@x, @y, @z);
 }
-/** @deprecated */
 .rotate(@degrees) {
   transform: rotate(@degrees);
 }
-/** @deprecated */
 .rotateX(@degrees) {
   transform: rotateX(@degrees);
 }
-/** @deprecated */
 .rotateY(@degrees) {
   transform: rotateY(@degrees);
 }
-/** @deprecated */
 .perspective(@perspective) {
   perspective: @perspective;
 }
-/** @deprecated */
 .perspective-origin(@perspective) {
   perspective-origin: @perspective;
 }
-/** @deprecated */
 .transform-origin(@origin) {
   transform-origin: @origin;
 }
 
 // Transitions
 // These remain for backwards compatibility with existing styles.
-/** @deprecated */
 .transition(@transition) {
   transition: @transition;
 }
-/** @deprecated */
 .transition-property(@transition-property) {
   transition-property: @transition-property;
 }
-/** @deprecated */
 .transition-delay(@transition-delay) {
   transition-delay: @transition-delay;
 }
-/** @deprecated */
 .transition-duration(@transition-duration) {
   transition-duration: @transition-duration;
 }
-/** @deprecated */
 .transition-timing-function(@timing-function) {
   transition-timing-function: @timing-function;
 }
-/** @deprecated */
 .transition-transform(@transition) {
   transition: transform @transition;
 }
diff --git a/less/common/scaffolding.less b/less/common/scaffolding.less
index cf6b75d48a..3292a18dd6 100644
--- a/less/common/scaffolding.less
+++ b/less/common/scaffolding.less
@@ -2,7 +2,7 @@
   &,
   &:before,
   &:after {
-    box-sizing: border-box;
+    .box-sizing(border-box);
   }
 }
 
@@ -114,7 +114,7 @@ input[type="search"] {
 
 .fade {
   opacity: 0;
-  transition: opacity .15s linear;
+  .transition(opacity .15s linear);
   &.in {
     opacity: 1;
   }
diff --git a/less/forum/Composer.less b/less/forum/Composer.less
index d33147e868..c31b9918ee 100644
--- a/less/forum/Composer.less
+++ b/less/forum/Composer.less
@@ -3,7 +3,7 @@
 
 .Composer {
   pointer-events: auto;
-  box-shadow: 0 2px 6px @shadow-color;
+  .box-shadow(0 2px 6px @shadow-color);
 
   &.minimized {
     height: 46px;
@@ -221,20 +221,20 @@
     right: 0;
     z-index: @zindex-composer;
     pointer-events: none;
-    transition: left 0.2s;
+    .transition(left 0.2s);
   }
   .Composer {
     border-radius: @border-radius @border-radius 0 0;
     background: fade(@body-bg, 95%);
     position: relative;
     height: 300px;
-    transition: background 0.2s, box-shadow 0.2s;
+    .transition(~"background 0.2s, box-shadow 0.2s");
 
     &.active, &.fullScreen {
       background: @body-bg;
     }
     &.active:not(.fullScreen) {
-      box-shadow: 0 0 0 2px @primary-color, 0 2px 6px @shadow-color;
+      .box-shadow(~"0 0 0 2px @{primary-color}, 0 2px 6px @{shadow-color}");
     }
     &.fullScreen {
       position: fixed;
diff --git a/less/forum/DiscussionPage.less b/less/forum/DiscussionPage.less
index a283d23d8b..391869a886 100644
--- a/less/forum/DiscussionPage.less
+++ b/less/forum/DiscussionPage.less
@@ -79,8 +79,8 @@
     background: @body-bg;
     padding-bottom: 40px;
     border-top: 1px solid @control-bg;
-    box-shadow: 0 6px 6px @shadow-color;
-    transition: left 0.2s;
+    .box-shadow(0 6px 6px @shadow-color);
+    .transition(left 0.2s);
 
     .affix & {
       position: fixed;
@@ -128,7 +128,7 @@
   .DiscussionPage-list {
     .panePinned & {
       left: 0;
-      transition: none;
+      .transition(none);
     }
   }
   // When the pane is pinned, move the other page content inwards
diff --git a/less/forum/NotificationsDropdown.less b/less/forum/NotificationsDropdown.less
index 5b5e9c0f31..3d3564e11b 100644
--- a/less/forum/NotificationsDropdown.less
+++ b/less/forum/NotificationsDropdown.less
@@ -37,7 +37,7 @@
   padding: 2px 4px 3px;
   line-height: 1em;
   border-radius: 10px;
-  box-shadow: 0 0 0 1px @header-bg;
+  .box-shadow(0 0 0 1px @header-bg);
   min-width: 16px;
   height: 16px;
   text-align: center;
diff --git a/less/forum/Post.less b/less/forum/Post.less
index e29a2b4094..f063cad048 100644
--- a/less/forum/Post.less
+++ b/less/forum/Post.less
@@ -65,7 +65,7 @@
     top: -10px;
     left: -100px;
     z-index: @zindex-dropdown;
-    transition: opacity 0.2s, transform 0.2s;
+    .transition(~"opacity 0.2s, transform 0.2s");
     transform: scale(0.95);
     transform-origin: left top;
     opacity: 0;
@@ -297,7 +297,7 @@
   float: right;
   position: relative;
 
-  transition: opacity 0.2s;
+  .transition(opacity 0.2s);
 
   .EventPost &, .Post--hidden:not(.revealContent) & {
     margin-top: -27px;
diff --git a/less/forum/PostStream.less b/less/forum/PostStream.less
index 400ba77f88..9e649cb3ba 100644
--- a/less/forum/PostStream.less
+++ b/less/forum/PostStream.less
@@ -22,8 +22,14 @@
   50% {opacity: 1}
   100% {opacity: 0.5}
 }
+@-webkit-keyframes blink {
+  0% {opacity: 0.5}
+  50% {opacity: 1}
+  100% {opacity: 0.5}
+}
 .LoadingPost {
-  animation: blink 1s linear infinite;
+  .animation(blink 1s linear);
+  .animation-iteration-count(infinite);
 }
 .fakeText {
   display: inline-block;
@@ -57,22 +63,46 @@
   }
 }
 
+// .item.highlight .post {
+//   &:before {
+//     content: "";
+//     position: absolute;
+//     left: -30px;
+//     top: -5px;
+//     bottom: -5px;
+//     width: 5px;
+//     border-radius: @border-radius;
+//     background: @fl-primary-color;
+//   }
+// }
+@-webkit-keyframes pulsate {
+  0% {-webkit-transform: scale(1)}
+  50% {-webkit-transform: scale(1.02)}
+  100% {-webkit-transform: scale(1)}
+}
 @keyframes pulsate {
   0% {transform: scale(1)}
   50% {transform: scale(1.02)}
   100% {transform: scale(1)}
 }
 .pulsate {
-  animation: pulsate 1s ease-in-out infinite;
+  .animation(pulsate 1s ease-in-out);
+  .animation-iteration-count(infinite);
 }
 .flash {
-  animation: pulsate 0.2s ease-in-out;
+  .animation(pulsate 0.2s ease-in-out);
+  .animation-iteration-count(1);
 }
 
+@-webkit-keyframes fadeIn {
+  0% {opacity: 0}
+  100% {opacity: 1}
+}
 @keyframes fadeIn {
   0% {opacity: 0}
   100% {opacity: 1}
 }
 .fadeIn {
-  animation: fadeIn 0.4s ease-in-out;
+  .animation(fadeIn 0.4s ease-in-out);
+  .animation-iteration-count(1);
 }
diff --git a/less/forum/SignUpModal.less b/less/forum/SignUpModal.less
index e69de29bb2..d30b57b284 100644
--- a/less/forum/SignUpModal.less
+++ b/less/forum/SignUpModal.less
@@ -0,0 +1,48 @@
+.SignUpModal-welcome {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  border-radius: @border-radius;
+  text-align: center;
+  color: #fff;
+  font-size: 14px;
+
+  .light-contents();
+
+  .Avatar {
+    .Avatar--size(96px);
+    border: 4px solid @body-bg;
+    .box-shadow(0 2px 6px @shadow-color);
+  }
+  h3, p {
+    margin-bottom: 25px;
+  }
+  .Button {
+    font-size: 15px;
+    height: 50px;
+    padding: 15px 20px;
+  }
+  .darkenBackground {
+    position: absolute;
+    top: 0;
+    left: 0;
+    bottom: 0;
+    right: 0;
+  }
+  .container {
+    width: auto !important;
+    padding: 50px 30px !important;
+    position: relative;
+  }
+}
+.SignUpModal--success .Modal-close .Button {
+  color: #fff;
+}
+
+@media @phone {
+  .SignUpModal-welcome .container {
+    padding-top: 56px + 60px;
+  }
+}
diff --git a/less/forum/Slidable.less b/less/forum/Slidable.less
index f0610d3760..83d60eefc3 100644
--- a/less/forum/Slidable.less
+++ b/less/forum/Slidable.less
@@ -23,7 +23,7 @@
       color: #fff !important;
       border: 0;
       border-radius: 0;
-      box-shadow: none;
+      .box-shadow(none);
       padding: 20px 0;
       text-align: right;
 
@@ -40,14 +40,14 @@
       left: unset;
     }
     .Slidable-content {
-      transition: box-shadow 0.2s, border-radius 0.2s;
+      .transition(~"box-shadow 0.2s, border-radius 0.2s");
 
       .sliding& {
         position: relative;
         background: @control-bg;
         z-index: 2;
         border-radius: 2px;
-        box-shadow: 0 2px 6px @shadow-color;
+        .box-shadow(0 2px 6px @shadow-color);
       }
     }
   }
diff --git a/less/forum/UserCard.less b/less/forum/UserCard.less
index a19e9682d4..29b4d4f0f6 100644
--- a/less/forum/UserCard.less
+++ b/less/forum/UserCard.less
@@ -13,7 +13,7 @@
 }
 .UserCard--popover {
   width: 500px;
-  box-shadow: 0 2px 6px @shadow-color;
+  .box-shadow(0 2px 6px @shadow-color);
 
   &, .darkenBackground {
     border-radius: @border-radius;
@@ -64,7 +64,7 @@
   .Avatar {
     .Avatar--size(96px);
     border: 4px solid #fff;
-    box-shadow: 0 2px 6px @shadow-color;
+    .box-shadow(0 2px 6px @shadow-color);
 
     @media @phone {
       .Avatar--size(64px);