make less files compile with strict maths in 1.4.0

less/code.less

@@ -8,7 +8,7 @@ code,
 pre {
   padding: 0 3px 2px;
   #font > #family > .monospace;
-  font-size: @font-size-base - 2;
+  font-size: (@font-size-base - 2);
   color: @grayDark;
   border-radius: 4px;
 }
@@ -25,9 +25,9 @@ code {
 // Blocks of code
 pre {
   display: block;
-  padding: (@line-height-base - 1) / 2;
-  margin: 0 0 @line-height-base / 2;
-  font-size: @font-size-base - 1; // 14px to 13px
+  padding: ((@line-height-base - 1) / 2);
+  margin: 0 0 (@line-height-base / 2);
+  font-size: (@font-size-base - 1); // 14px to 13px
   line-height: @line-height-base;
   word-break: break-all;
   word-wrap: break-word;

less/forms.less

@@ -21,8 +21,8 @@ legend {
   width: 100%;
   padding: 0;
   margin-bottom: @line-height-base;
-  font-size: @font-size-base * 1.5;
-  line-height: @line-height-base * 2;
+  font-size: (@font-size-base * 1.5);
+  line-height: (@line-height-base * 2);
   color: @grayDark;
   border: 0;
   border-bottom: 1px solid #e5e5e5;
@@ -58,7 +58,7 @@ input[type="color"] {
   .box-sizing(border-box); // Makes inputs behave like true block-level elements
   min-height: @input-height-base; // Make inputs at least the height of their button counterpart (base line-height + padding + border)
   padding: 6px 9px;
-  // margin-bottom: @line-height-base / 2;
+  // margin-bottom: (@line-height-base / 2);
   font-size: @font-size-base;
   line-height: @line-height-base;
   color: @gray;
@@ -168,7 +168,7 @@ textarea {
 .checkbox {
   display: block;
   min-height: @line-height-base; // clear the floating input if there is no label text
-  margin-bottom: @line-height-base / 2;
+  margin-bottom: (@line-height-base / 2);
   padding-left: 20px;
   label {
     display: inline;
@@ -186,7 +186,7 @@ textarea {
 }
 .radio + .radio,
 .checkbox + .checkbox {
-  margin-top: (@line-height-base / 4) * -1;
+  margin-top: ((@line-height-base / 4) * -1);
 }
 
 // Move the options list down to align with labels
@@ -359,7 +359,7 @@ select:focus:invalid {
 
 .help-block {
   display: block; // account for any element using help-block
-  margin-bottom: @line-height-base / 2;
+  margin-bottom: (@line-height-base / 2);
 }
 
 .help-inline {
@@ -530,7 +530,7 @@ select:focus:invalid {
     // Float the labels left
     .control-group > .control-label {
       float: left;
-      width: @component-offset-horizontal - 20;
+      width: (@component-offset-horizontal - 20);
       padding-top: 6px;
       text-align: right;
     }

less/grid.less

@@ -10,14 +10,14 @@
 
 // Mobile-first defaults
 .row {
-  margin-left:  @grid-gutter-width / -2;
-  margin-right: @grid-gutter-width / -2;
+  margin-left:  (@grid-gutter-width / -2);
+  margin-right: (@grid-gutter-width / -2);
   .clear_float();
 }
 [class^="span"] {
   min-height: 1px;
-  padding-left:  @grid-gutter-width / 2;
-  padding-right: @grid-gutter-width / 2;
+  padding-left:  (@grid-gutter-width / 2);
+  padding-right: (@grid-gutter-width / 2);
   // Proper box-model (padding doesn't add to width)
   -webkit-box-sizing: border-box;
      -moz-box-sizing: border-box;

less/jumbotron.less

@@ -8,7 +8,7 @@
   margin-bottom: 30px;
   font-size: 21px;
   font-weight: 200;
-  line-height: @line-height-base * 1.5;
+  line-height: (@line-height-base * 1.5);
   color: @jumbotron-lead-color;
   background-color: @jumbotron-background;
   h1 {

less/mixins.less

@@ -293,7 +293,7 @@
 .opacity(@opacity) {
   opacity: @opacity;
   // IE8 filter
-  @opacity-ie: @opacity * 100;
+  @opacity-ie: (@opacity * 100);
   filter: ~"alpha(opacity=@{opacity-ie})";
 }
 
@@ -423,8 +423,8 @@
 // Vertically center elements in the navbar.
 // Example: an element has a height of 30px, so write out `.navbarVerticalAlign(30px);` to calculate the appropriate top margin.
 .navbar-vertical-align(@element-height) {
-  margin-top: (@navbar-height - @element-height) / 2;
-  margin-bottom: (@navbar-height - @element-height) / 2;
+  margin-top: ((@navbar-height - @element-height) / 2);
+  margin-bottom: ((@navbar-height - @element-height) / 2);
 }
 
 
@@ -471,22 +471,22 @@
 
     .spanX (@index) when (@index > 0) {
       .span@{index} { .span(@index); }
-      .spanX(@index - 1);
+      .spanX((@index - 1));
     }
     .spanX(0) {}
 
     .offsetX (@index) when (@index > 0) {
       .offset@{index} { .offset(@index); }
-      .offsetX(@index - 1);
+      .offsetX((@index - 1));
     }
     .offsetX (0) {}
 
     // Base styles
     .offset(@columns) {
-      margin-left: percentage(@columns / @grid-columns);
+      margin-left: percentage((@columns / @grid-columns));
     }
     .span(@columns) {
-      width: percentage(@columns / @grid-columns);
+      width: percentage((@columns / @grid-columns));
     }
 
     // Generate .spanX and .offsetX

less/modals.less

@@ -41,7 +41,7 @@
   right: 0;
   width: auto;
   padding: 10px;
-  z-index: @zindex-modal-background + 10;
+  z-index: (@zindex-modal-background + 10);
 }
 
 // Actual modal
@@ -64,7 +64,7 @@
   right: 0;
   bottom: 0;
   left: 0;
-  z-index: @zindex-modal-background - 10;
+  z-index: (@zindex-modal-background - 10);
   background-color: #000;
   // Fade for backdrop
   &.fade { .opacity(0); }

less/navbar.less

@@ -21,8 +21,8 @@
     margin-top: 15px;
   }
   .nav > li > a {
-    padding-top: (@navbar-height - @line-height-base) / 2;
-    padding-bottom: (@navbar-height - @line-height-base) / 2;
+    padding-top: ((@navbar-height - @line-height-base) / 2);
+    padding-bottom: ((@navbar-height - @line-height-base) / 2);
     color: @navbar-link-color;
     line-height: 20px;
   }
@@ -276,8 +276,8 @@
   }
   .navbar-brand {
     float: left;
-    padding-top: (@navbar-height - @line-height-base) / 2;
-    padding-bottom: (@navbar-height - @line-height-base) / 2;
+    padding-top: ((@navbar-height - @line-height-base) / 2);
+    padding-bottom: ((@navbar-height - @line-height-base) / 2);
     margin-left: -10px;
   }
   .navbar .nav {
@@ -297,7 +297,7 @@
   // Change the height and height, disable bottom border, then add right border
   .navbar .nav > .divider {
     width: 1px;
-    height: @navbar-height * .6;
+    height: (@navbar-height * .6);
     margin: (@navbar-height * .2) 9px;
     border-bottom: 0;
     border-right: 1px solid lighten(@navbar-bg, 5%);

less/type.less

@@ -7,11 +7,11 @@
 // -------------------------
 
 p {
-  margin: 0 0 @line-height-base / 2;
+  margin: 0 0 (@line-height-base / 2);
 }
 .lead {
   margin-bottom: @line-height-base;
-  font-size: @font-size-base * 1.5;
+  font-size: (@font-size-base * 1.5);
   font-weight: 200;
   line-height: 1.25;
 }
@@ -68,28 +68,28 @@ h1,
 h2,
 h3 {
   margin-top: @line-height-base;
-  margin-bottom: @line-height-base / 2;
-  line-height: @line-height-base * 2;
+  margin-bottom: (@line-height-base / 2);
+  line-height: (@line-height-base * 2);
 }
 h3 {
-  line-height: @line-height-base * 1.5;
+  line-height: (@line-height-base * 1.5);
 }
 h4,
 h5,
 h6 {
-  margin-top: @line-height-base / 2;
-  margin-bottom: @line-height-base / 2;
+  margin-top: (@line-height-base / 2);
+  margin-bottom: (@line-height-base / 2);
 }
 
-h1 { font-size: @font-size-base * 2.75; font-size: 4rem; } // ~38px
-h2 { font-size: @font-size-base * 2.25; font-size: 3rem; } // ~32px
-h3 { font-size: @font-size-base * 1.75; font-size: 2.5rem; } // ~24px
-h4 { font-size: @font-size-base * 1.25; font-size: 2rem; } // ~18px
-h5 { font-size: @font-size-base; font-size: 1.6rem; }
-h6 { font-size: @font-size-base * 0.85; font-size: 1.2rem; } // ~12px
+h1 { font-size: (@font-size-base * 2.75); font-size: 4rem; } // ~38px
+h2 { font-size: (@font-size-base * 2.25); font-size: 3rem; } // ~32px
+h3 { font-size: (@font-size-base * 1.75); font-size: 2.5rem; } // ~24px
+h4 { font-size: (@font-size-base * 1.25); font-size: 2rem; } // ~18px
+h5 { font-size:  @font-size-base; font-size: 1.6rem; }
+h6 { font-size: (@font-size-base * 0.85); font-size: 1.2rem; } // ~12px
 
-h1 small { font-size: @font-size-base * 1.75; } // ~24px
-h2 small { font-size: @font-size-base * 1.25; } // ~18px
+h1 small { font-size: (@font-size-base * 1.75); } // ~24px
+h2 small { font-size: (@font-size-base * 1.25); } // ~18px
 h3 small { font-size: @font-size-base; }
 h4 small { font-size: @font-size-base; }
 
@@ -98,7 +98,7 @@ h4 small { font-size: @font-size-base; }
 // -------------------------
 
 .page-header {
-  padding-bottom: (@line-height-base / 2) - 1;
+  padding-bottom: ((@line-height-base / 2) - 1);
   margin: (@line-height-base * 2) 0 @line-height-base;
   border-bottom: 1px solid @grayLighter;
 }
@@ -151,14 +151,14 @@ dt {
   font-weight: bold;
 }
 dd {
-  margin-left: @line-height-base / 2;
+  margin-left: (@line-height-base / 2);
 }
 // Horizontal layout (like forms)
 .dl-horizontal {
   .clear_float(); // Ensure dl clears floats if empty dd elements present
   dt {
     float: left;
-    width: @component-offset-horizontal - 20;
+    width: (@component-offset-horizontal - 20);
     clear: left;
     text-align: right;
     .text-overflow();
@@ -198,7 +198,7 @@ blockquote {
   border-left: 5px solid @grayLighter;
   p {
     margin-bottom: 0;
-    font-size: @font-size-base * 1.25;
+    font-size: (@font-size-base * 1.25);
     font-weight: 300;
     line-height: 1.25;
   }

less/variables.less

@@ -46,9 +46,9 @@
 @font-family-base:        @font-family-sans-serif;
 
 @font-size-base:          14px;
-@font-size-large:         @font-size-base * 1.25; // ~18px
-@font-size-small:         @font-size-base * 0.85; // ~12px
-@font-size-mini:          @font-size-base * 0.75; // ~11px
+@font-size-large:         (@font-size-base * 1.25); // ~18px
+@font-size-small:         (@font-size-base * 0.85); // ~12px
+@font-size-mini:          (@font-size-base * 0.75); // ~11px
 
 @line-height-base:        20px;
 
@@ -115,9 +115,9 @@
 
 @input-color-placeholder:        @grayLight;
 
-@input-height-base:              @line-height-base + 14px; // base line-height + 12px vertical padding + 2px top/bottom border
-@input-height-large:             @line-height-base + 24px; // base line-height + 22px vertical padding + 2px top/bottom border
-@input-height-small:             @line-height-base + 6px;  // base line-height + 4px vertical padding + 2px top/bottom border
+@input-height-base:              (@line-height-base + 14px); // base line-height + 12px vertical padding + 2px top/bottom border
+@input-height-large:             (@line-height-base + 24px); // base line-height + 22px vertical padding + 2px top/bottom border
+@input-height-small:             (@line-height-base + 6px);  // base line-height + 4px vertical padding + 2px top/bottom border
 
 // adjust min-height on input sizes
 
@@ -266,7 +266,7 @@
 @popover-title-background:    darken(@popover-background, 3%);
 
 // Special enhancement for popovers
-@popover-arrow-outer-width:   @popover-arrow-width + 1;
+@popover-arrow-outer-width:   (@popover-arrow-width + 1);
 @popover-arrow-outer-color:   rgba(0,0,0,.25);
 
 
@@ -315,4 +315,4 @@
 @grid-columns:              12;
 @grid-column-width:         60px;
 @grid-gutter-width:         20px;
-@grid-row-width:            (@grid-columns * @grid-column-width) + (@grid-gutter-width * (@grid-columns - 1));
+@grid-row-width:            ((@grid-columns * @grid-column-width) + (@grid-gutter-width * (@grid-columns - 1)));