add unit `px` to all less value, make them explicit

components/auto-complete/style/index.less

@@ -19,8 +19,8 @@
           line-height: @input-height-base;
         }
         &__placeholder {
-          margin-left: (@input-padding-horizontal + 1);
-          margin-right: (@input-padding-horizontal + 1);
+          margin-left: (@input-padding-horizontal + 1px);
+          margin-right: (@input-padding-horizontal + 1px);
         }
       }
     }

components/button/style/mixin.less

@@ -224,11 +224,11 @@
 // circle button: the content only contains icon
 .btn-circle(@btnClassName: btn) {
   .square(@btn-circle-size);
-  .button-size(@btn-circle-size; 0; @font-size-base + 2; 50%);
+  .button-size(@btn-circle-size; 0; @font-size-base + 2px; 50%);
 
   &.@{btnClassName}-lg {
     .square(@btn-circle-size-lg);
-    .button-size(@btn-circle-size-lg; 0; @btn-font-size-lg + 2; 50%);
+    .button-size(@btn-circle-size-lg; 0; @btn-font-size-lg + 2px; 50%);
   }
 
   &.@{btnClassName}-sm {

components/input/style/mixin.less

@@ -1,7 +1,7 @@
 @import "../../style/themes/default";
 @import "../../style/mixins/index";
 
-@input-affix-width: 17;
+@input-affix-width: 17px;
 
 // size mixins for input
 .input-lg() {
@@ -148,7 +148,7 @@
 
     // Reset Select's style in addon
     .@{ant-prefix}-select {
-      margin: -(@input-padding-vertical-base + 1) (-@input-padding-horizontal);  // lesshint spaceAroundOperator: false
+      margin: -(@input-padding-vertical-base + 1px) (-@input-padding-horizontal);  // lesshint spaceAroundOperator: false
 
       .@{ant-prefix}-select-selection {
         background-color: inherit;

components/input/style/search-input.less

@@ -35,7 +35,7 @@
 
   .@{ant-prefix}-search-btn {
     .btn-default;
-    border-radius: 0 @border-radius-base - 1 @border-radius-base - 1 0;
+    border-radius: 0 @border-radius-base - 1px @border-radius-base - 1px 0;
     left: -1px;
     position: relative;
     border-width: 0 0 0 1px;

components/radio/style/index.less

@@ -136,7 +136,7 @@ span.@{radio-prefix-cls} + * {
 .@{radio-prefix-cls}-button-wrapper {
   margin: 0;
   height: @input-height-base;
-  line-height: @input-height-base - 2;
+  line-height: @input-height-base - 2px;
   color: @radio-button-color;
   display: inline-block;
   transition: all 0.3s ease;
@@ -165,7 +165,7 @@ span.@{radio-prefix-cls} + * {
 
   .@{radio-group-prefix-cls}-small & {
     height: @input-height-sm;
-    line-height: @input-height-sm - 2;
+    line-height: @input-height-sm - 2px;
     padding: 0 12px;
     &:first-child {
       border-radius: @border-radius-sm 0 0 @border-radius-sm;

components/slider/style/index.less

@@ -8,7 +8,7 @@
 @slider-tooltip-color: #fff;
 @slider-tooltip-bg: tint(@text-color, 4%);
 @slider-tooltip-arrow-width: 4px;
-@slider-tooltip-distance: @slider-tooltip-arrow-width + 4;
+@slider-tooltip-distance: @slider-tooltip-arrow-width + 4px;
 @slider-tooltip-arrow-color: @slider-tooltip-bg;
 
 .@{slider-prefix-cls} {

components/spin/style/index.less

@@ -41,10 +41,10 @@
         position: absolute;
         top: 50%;
         width: 100%;
-        padding-top: (@spin-dot-size - @font-size-base) / 2 + 2;
+        padding-top: (@spin-dot-size - @font-size-base) / 2 + 2px;
       }
       &.@{spin-prefix-cls}-show-text .@{spin-prefix-cls}-dot {
-        margin-top: -@spin-dot-size / 2 - 10;
+        margin-top: -@spin-dot-size / 2 - 10px;
       }
     }
 
@@ -53,10 +53,10 @@
         margin: -@spin-dot-size-sm / 2;
       }
       .@{spin-prefix-cls}-text {
-        padding-top: (@spin-dot-size-sm - @font-size-base) / 2 + 2;
+        padding-top: (@spin-dot-size-sm - @font-size-base) / 2 + 2px;
       }
       &.@{spin-prefix-cls}-show-text .@{spin-prefix-cls}-dot {
-        margin-top: -@spin-dot-size-sm / 2 - 10;
+        margin-top: -@spin-dot-size-sm / 2 - 10px;
       }
     }
 
@@ -65,10 +65,10 @@
         margin: -@spin-dot-size-lg / 2;
       }
       .@{spin-prefix-cls}-text {
-        padding-top: (@spin-dot-size-lg - @font-size-base) / 2 + 2;
+        padding-top: (@spin-dot-size-lg - @font-size-base) / 2 + 2px;
       }
       &.@{spin-prefix-cls}-show-text .@{spin-prefix-cls}-dot {
-        margin-top: -@spin-dot-size-lg / 2 - 10;
+        margin-top: -@spin-dot-size-lg / 2 - 10px;
       }
     }
   }

components/style/themes/default.less

@@ -172,10 +172,10 @@
 @screen-xl-min          : @screen-xl;
 
 // provide a maximum
-@screen-xs-max          : (@screen-sm-min - 1);
-@screen-sm-max          : (@screen-md-min - 1);
-@screen-md-max          : (@screen-lg-min - 1);
-@screen-lg-max          : (@screen-xl-min - 1);
+@screen-xs-max          : (@screen-sm-min - 1px);
+@screen-sm-max          : (@screen-md-min - 1px);
+@screen-md-max          : (@screen-lg-min - 1px);
+@screen-lg-max          : (@screen-xl-min - 1px);
 
 // Grid system
 @grid-columns           : 24;
@@ -244,7 +244,7 @@
 //** Tooltip arrow width
 @tooltip-arrow-width: 5px;
 //** Tooltip distance with trigger
-@tooltip-distance: @tooltip-arrow-width - 1 + 4;
+@tooltip-distance: @tooltip-arrow-width - 1px + 4px;
 //** Tooltip arrow color
 @tooltip-arrow-color: @tooltip-bg;
 
@@ -261,11 +261,11 @@
 //** Popover arrow color
 @popover-arrow-color: @popover-bg;
 //** Popover outer arrow width
-@popover-arrow-outer-width: (@popover-arrow-width + 1);
+@popover-arrow-outer-width: (@popover-arrow-width + 1px);
 //** Popover outer arrow color
 @popover-arrow-outer-color: fadeout(@border-color-base, 30%);
 //** Popover distance with trigger
-@popover-distance: @popover-arrow-width + 4;
+@popover-distance: @popover-arrow-width + 4px;
 
 // Modal
 // --