clarify usage of base font-size so we know what's up

scss/_close.scss

@@ -1,6 +1,6 @@
 .close {
   float: right;
-  font-size: ($font-size-base * 1.5);
+  font-size: $close-font-size;
   font-weight: $close-font-weight;
   line-height: 1;
   color: $close-color;

scss/_dropdown.scss

@@ -44,7 +44,7 @@
   min-width: $dropdown-min-width;
   padding: $dropdown-padding-y 0;
   margin: $dropdown-margin-top 0 0; // override default ul
-  font-size: $font-size-base;
+  font-size: $font-size-base; // Redeclare because nesting can cause inheritance issues
   color: $body-color;
   text-align: left; // Ensures proper alignment if parent has it changed (e.g., modal footer)
   list-style: none;

scss/_input-group.scss

@@ -69,7 +69,7 @@
 .input-group-addon {
   padding: $input-padding-y $input-padding-x;
   margin-bottom: 0; // Allow use of <label> elements by overriding our default margin-bottom
-  font-size: $font-size-base;
+  font-size: $font-size-base; // Match inputs
   font-weight: $font-weight-normal;
   line-height: $input-line-height;
   color: $input-color;

scss/_popover.scss

@@ -130,7 +130,7 @@
 // Offset the popover to account for the popover arrow
 .popover-title {
   padding: $popover-title-padding-y $popover-title-padding-x;
-  margin: 0; // reset heading margin
+  margin-bottom: 0; // Reset the default from Reboot
   font-size: $font-size-base;
   background-color: $popover-title-bg;
   border-bottom: $popover-border-width solid darken($popover-title-bg, 5%);

scss/_variables.scss

@@ -938,6 +938,7 @@ $carousel-transition:           transform .6s ease-in-out !default;
 
 // Close
 
+$close-font-size:             $font-size-base * 1.5 !default;
 $close-font-weight:           $font-weight-bold !default;
 $close-color:                 $black !default;
 $close-text-shadow:           0 1px 0 $white !default;