fix affix…

assets/css/docs.css

@@ -737,7 +737,6 @@ input.focused {
     right:  15px;
     bottom: 15px;
   }
-
   .bs-header {
     font-size: 21px;
     text-align: left;
@@ -793,12 +792,22 @@ input.focused {
 @media screen and (min-width: 992px) {
 
   /* Widen the fixed sidebar */
+  .bs-sidebar.affix,
+  .bs-sidebar.affix-bottom {
+    width: 213px;
+  }
   .bs-sidebar.affix {
     position: fixed; /* Undo the static from mobile-first approach */
-    top: 50px;
-    width: 213px;
+    top: 80px;
+  }
+  .bs-sidebar.affix-bottom {
+    position: absolute; /* Undo the static from mobile-first approach */
+  }
+  .bs-sidebar.affix-bottom .bs-sidenav,
+  .bs-sidebar.affix .bs-sidenav {
+    margin-top: 0;
+    margin-bottom: 0;
   }
-
   .bs-header h1,
   .bs-header p {
     margin-right: 380px;
@@ -818,6 +827,7 @@ input.focused {
 @media screen and (min-width: 1200px) {
 
   /* Widen the fixed sidebar again */
+  .bs-sidebar.affix-bottom,
   .bs-sidebar.affix {
     width: 270px;
   }

assets/js/application.js

@@ -13,12 +13,23 @@
       e.preventDefault()
     })
 
+
     // back to top
     setTimeout(function () {
-      $('.bs-sidebar').affix({
+      var $sideBar = $('.bs-sidebar')
+
+      $sideBar.affix({
         offset: {
-          top: function () { return $window.width() <= 980 ? 290 : 210 }
-        , bottom: 270
+          top: function () {
+            var offsetTop      = $sideBar.offset().top
+            var sideBarMargin  = parseInt($sideBar.children(0).css('margin-top'), 10)
+            var navOuterHeight = $('.bs-docs-nav').height()
+
+            return (this.top = offsetTop - navOuterHeight - sideBarMargin)
+          }
+        , bottom: function () {
+            return (this.bottom = $('.bs-footer').outerHeight(true))
+          }
         }
       })
     }, 100)

dist/js/bootstrap.js

@@ -1842,6 +1842,8 @@ if (!jQuery) throw new Error("Bootstrap requires jQuery")
     this.checkPosition()
   }
 
+  Affix.RESET = 'affix affix-top affix-bottom'
+
   Affix.DEFAULTS = {
     offset: 0
   }
@@ -1859,7 +1861,6 @@ if (!jQuery) throw new Error("Bootstrap requires jQuery")
     var offset       = this.options.offset
     var offsetTop    = offset.top
     var offsetBottom = offset.bottom
-    var reset        = 'affix affix-top affix-bottom'
 
     if (typeof offset != 'object')         offsetBottom = offsetTop = offset
     if (typeof offsetTop == 'function')    offsetTop    = offset.top()
@@ -1870,11 +1871,16 @@ if (!jQuery) throw new Error("Bootstrap requires jQuery")
                 offsetTop    != null && (scrollTop <= offsetTop) ? 'top' : false
 
     if (this.affixed === affix) return
+    if (this.unpin) this.$element.css('top', '')
 
     this.affixed = affix
     this.unpin   = affix == 'bottom' ? position.top - scrollTop : null
 
-    this.$element.removeClass(reset).addClass('affix' + (affix ? '-' + affix : ''))
+    this.$element.removeClass(Affix.RESET).addClass('affix' + (affix ? '-' + affix : ''))
+
+    if (affix == 'bottom') {
+      this.$element.offset({ top: document.body.offsetHeight - offsetBottom - this.$element.height() })
+    }
   }
 
 

js/affix.js

@@ -36,6 +36,8 @@
     this.checkPosition()
   }
 
+  Affix.RESET = 'affix affix-top affix-bottom'
+
   Affix.DEFAULTS = {
     offset: 0
   }
@@ -53,7 +55,6 @@
     var offset       = this.options.offset
     var offsetTop    = offset.top
     var offsetBottom = offset.bottom
-    var reset        = 'affix affix-top affix-bottom'
 
     if (typeof offset != 'object')         offsetBottom = offsetTop = offset
     if (typeof offsetTop == 'function')    offsetTop    = offset.top()
@@ -64,11 +65,16 @@
                 offsetTop    != null && (scrollTop <= offsetTop) ? 'top' : false
 
     if (this.affixed === affix) return
+    if (this.unpin) this.$element.css('top', '')
 
     this.affixed = affix
     this.unpin   = affix == 'bottom' ? position.top - scrollTop : null
 
-    this.$element.removeClass(reset).addClass('affix' + (affix ? '-' + affix : ''))
+    this.$element.removeClass(Affix.RESET).addClass('affix' + (affix ? '-' + affix : ''))
+
+    if (affix == 'bottom') {
+      this.$element.offset({ top: document.body.offsetHeight - offsetBottom - this.$element.height() })
+    }
   }