diff --git a/themes/bootprint3/scss/bootprint.scss b/themes/bootprint3/scss/bootprint.scss
index c7463c8bdd1863993ed159a4633a2c250ed67617..e7b204be19ae906062260cad3a0f0f5b17cf726a 100644
--- a/themes/bootprint3/scss/bootprint.scss
+++ b/themes/bootprint3/scss/bootprint.scss
@@ -10,8 +10,8 @@
 @import "search";
 @import "forms";
 
-$brand-primary: #619144; /* a11y overrides $brand-primary in sass */
-$active-orange: #E70;
+$brand-primary: #619144 !default; /* a11y overrides $brand-primary in sass */
+$active-orange: #E70 !default;
 
 /* --- Bootstrap MODS ---*/
 @import "common";
diff --git a/themes/bootprint3/scss/icons.scss b/themes/bootprint3/scss/icons.scss
index 48823e0f51b1c30be1167f84658954a214a303a9..8c2885d47543ad68e0a680c0964e53353b6f8ec9 100644
--- a/themes/bootprint3/scss/icons.scss
+++ b/themes/bootprint3/scss/icons.scss
@@ -1,4 +1,4 @@
-$bp3-icon-path: '../../bootprint3/images/icons';
+$bp3-icon-path: '../../bootprint3/images/icons' !default;
 .doi-icon { width: 16px; }
 .bp-icon {
   background-position: center center;
diff --git a/themes/bootprint3/scss/variables.scss b/themes/bootprint3/scss/variables.scss
index dd2080deb69b44154cd96dc9b2a0223bb9bbac16..45a408d1e859b7f168c9ec595cbe47ab4472e5c1 100644
--- a/themes/bootprint3/scss/variables.scss
+++ b/themes/bootprint3/scss/variables.scss
@@ -1,39 +1,39 @@
-$brand-primary: #619144;
+$brand-primary: #619144 !default;
 
-$font-size-base: 13px;
+$font-size-base: 13px !default;
 
-$padding-base-vertical   : 3px;
-$padding-base-horizontal : 5px;
-$padding-large-vertical  : 8px;
-$padding-large-horizontal: 5px;
-$padding-small-vertical  : 1px;
-$padding-small-horizontal: 2px;
-$padding-xs-horizontal   : 1px;
+$padding-base-vertical   : 3px !default;
+$padding-base-horizontal : 5px !default;
+$padding-large-vertical  : 8px !default;
+$padding-large-horizontal: 5px !default;
+$padding-small-vertical  : 1px !default;
+$padding-small-horizontal: 2px !default;
+$padding-xs-horizontal   : 1px !default;
 
-$border-radius-base : 3px;
-$border-radius-large: 5px;
-$border-radius-small: 2px;
+$border-radius-base : 3px !default;
+$border-radius-large: 5px !default;
+$border-radius-small: 2px !default;
 
-$input-border-focus: $brand-primary;
+$input-border-focus: $brand-primary !default;
 
-$legend-border-color: #777; // $gray-light
+$legend-border-color: #777 !default; // $gray-light
 
-$grid-gutter-width: 14px;
+$grid-gutter-width: 14px !default;
 
-$container-desktop      : 952px;
-$container-large-desktop: 952px;
+$container-desktop      : 952px !default;
+$container-large-desktop: 952px !default;
 
-$navbar-height       : 65px;
-$navbar-margin-bottom: 0px;
-$nav-link-padding    : 5px;
+$navbar-height       : 65px !default;
+$navbar-margin-bottom: 0px !default;
+$nav-link-padding    : 5px !default;
 
-$pagination-active-bg    : #5bc0de; // $brand-info
-$pagination-active-border: #5bc0de; // $brand-info
+$pagination-active-bg    : #5bc0de !default; // $brand-info
+$pagination-active-border: #5bc0de !default; // $brand-info
 
-$panel-body-padding: 5px;
+$panel-body-padding: 5px !default;
 
-$breadcrumb-padding-vertical  : 6px;
-$breadcrumb-padding-horizontal: 20px;
-$breadcrumb-bg                : #FFF;
-$breadcrumb-color             : #777; // $gray-light
-$breadcrumb-active-color      : #333; // $gray-dark
\ No newline at end of file
+$breadcrumb-padding-vertical  : 6px !default;
+$breadcrumb-padding-horizontal: 20px !default;
+$breadcrumb-bg                : #FFF !default;
+$breadcrumb-color             : #777 !default; // $gray-light
+$breadcrumb-active-color      : #333 !default; // $gray-dark
\ No newline at end of file
diff --git a/themes/bootstrap3/scss/bootstrap.scss b/themes/bootstrap3/scss/bootstrap.scss
index 3b1ccd9bdbc096829e3dd854add7783fcd8b94f5..d67049de2aef5d8a78be127a24e9292529f871d8 100644
--- a/themes/bootstrap3/scss/bootstrap.scss
+++ b/themes/bootstrap3/scss/bootstrap.scss
@@ -3,7 +3,7 @@
 @import "vendor/font-awesome/font-awesome";
 <#LESS */
 /* #SCSS> */
-$fa-font-path: "../../bootstrap3/css/fonts";
+$fa-font-path: "../../bootstrap3/css/fonts" !default;
 @import "vendor/bootstrap";
 @import "vendor/font-awesome/font-awesome";
 /* <#SCSS */
diff --git a/themes/bootstrap3/scss/components/accessibility.scss b/themes/bootstrap3/scss/components/accessibility.scss
index a987269a49d2b6b67d5b32480ed54e4664283f8b..5951e2c8bc438cb75e3a26f2ea1221a48af9c70f 100644
--- a/themes/bootstrap3/scss/components/accessibility.scss
+++ b/themes/bootstrap3/scss/components/accessibility.scss
@@ -8,12 +8,12 @@ a {
 }
 
 /* AAA Color Contrasts */
-$badge-bg: #595959;
+$badge-bg: #595959 !default;
 
-$breadcrumb-color: #535353;
-$breadcrumb-active-color: #444;
+$breadcrumb-color: #535353 !default;
+$breadcrumb-active-color: #444 !default;
 
-$state-danger-text: #8a211e;
+$state-danger-text: #8a211e !default;
 .alert-danger,
 .alert-danger a {
   color: $state-danger-text;
diff --git a/themes/bootstrap3/scss/components/autocomplete.scss b/themes/bootstrap3/scss/components/autocomplete.scss
index 78714f48835ccdce3e47dffde3205bfe7c85abd4..4d72a36ed4f8ea1d37a9e7fef895ba6db69a066c 100644
--- a/themes/bootstrap3/scss/components/autocomplete.scss
+++ b/themes/bootstrap3/scss/components/autocomplete.scss
@@ -1,9 +1,9 @@
 /* https://github.com/vufind-org/autocomplete.js 1.0b */
-$autocomplete-item-bg   : #fff;
-$autocomplete-active-bg : $brand-primary;
-$autocomplete-hover-bg  : lighten($brand-primary, 40%);
-$autocomplete-border    : lightgray;
-$autocomplete-secondary : darkgray; // item description
+$autocomplete-item-bg   : #fff !default;
+$autocomplete-active-bg : $brand-primary !default;
+$autocomplete-hover-bg  : lighten($brand-primary, 40%) !default;
+$autocomplete-border    : lightgray !default;
+$autocomplete-secondary : darkgray !default; // item description
 
 .autocomplete-results {
   position: absolute;
diff --git a/themes/bootstrap3/scss/components/lightbox.scss b/themes/bootstrap3/scss/components/lightbox.scss
index b1af70eb615c7d225ff774bfd69525af9c104d0c..32da48c274bc323e86e55cf403b8c22a369ee35e 100644
--- a/themes/bootstrap3/scss/components/lightbox.scss
+++ b/themes/bootstrap3/scss/components/lightbox.scss
@@ -34,6 +34,13 @@
   margin-bottom: 1.3rem;
 }
 
+#modal-title {
+  display: block;
+  padding: 0.8rem 1rem 0.7rem;
+  font-size: 23px;
+  font-weight: normal;
+}
+
 #modal .cart-controls .btn { margin-bottom: 4px; }
 #modal .cart-controls .checkbox { padding-bottom: 1rem; }
 #modal .cart-controls ~ hr { margin-top: 0; }
@@ -48,4 +55,4 @@ body.rtl .modal-loading { float: left; }
 #modal .lightbox-only { display: initial; }
 
 // Image display
-.lightbox-image { text-align: center; }
\ No newline at end of file
+.lightbox-image { text-align: center; }
diff --git a/themes/bootstrap3/scss/components/offcanvas.scss b/themes/bootstrap3/scss/components/offcanvas.scss
index 943ce7bbd656b063ddb509eda1aa607e08c89825..25140559c0f8a123c5bdee11ba40b85793be09ba 100644
--- a/themes/bootstrap3/scss/components/offcanvas.scss
+++ b/themes/bootstrap3/scss/components/offcanvas.scss
@@ -1,4 +1,4 @@
-$offcanvas-offset: 80vw;  // Width of open menu
+$offcanvas-offset: 80vw !default;  // Width of open menu
 
 .offcanvas-overlay { display: none; }
 
diff --git a/themes/bootstrap3/scss/components/search.scss b/themes/bootstrap3/scss/components/search.scss
index cb9dc7aa975a3fd3619ececec78e83a0b31f9ecf..278bf276be9a957f75bb825b5dd8bf8fea9e326d 100644
--- a/themes/bootstrap3/scss/components/search.scss
+++ b/themes/bootstrap3/scss/components/search.scss
@@ -1,7 +1,7 @@
 // Thumbnail sizes for media items: search results, list entries, record views
-$thumbnail-width-small:   60px;
-$thumbnail-width-medium: 100px;
-$thumbnail-width-large:  160px;
+$thumbnail-width-small:   60px !default;
+$thumbnail-width-medium: 100px !default;
+$thumbnail-width-large:  160px !default;
 
 // Hide these on mobile
 @media (max-width: 767px) {
diff --git a/themes/bootstrap3/scss/components/variables.scss b/themes/bootstrap3/scss/components/variables.scss
index 5603a0c582641c28344123d09f559101f2fe76cd..da161c60fe9cf4e284a28384bc658635ef2ca245 100644
--- a/themes/bootstrap3/scss/components/variables.scss
+++ b/themes/bootstrap3/scss/components/variables.scss
@@ -1,6 +1,6 @@
 // Make sure Font Awesome icons are loaded properly
 /* #LESS>
-$fa-font-path: "../../../../../../themes/bootstrap3/css/fonts";
+$fa-font-path: "../../../../../../themes/bootstrap3/css/fonts" !default;
 <#LESS */
 
 /**
@@ -8,47 +8,47 @@ $fa-font-path: "../../../../../../themes/bootstrap3/css/fonts";
  * with comments and their defaults. See /themes/bootstrap3/less/vendor/bootstrap/variables.less for more.
  */
 
-// $padding-base-vertical:   6px;  // Buttons, tabs, and other padding
-// $padding-base-horizontal: 12px;
+// $padding-base-vertical:   6px !default;  // Buttons, tabs, and other padding
+// $padding-base-horizontal: 12px !default;
 
-// $navbar-height:                    50px;
+// $navbar-height:                    50px !default;
 
-// $border-radius-base: 4px;
+// $border-radius-base: 4px !default;
 
 /* ------ COLORS ------ */
 
-// $gray-base:    #000;
-// $gray-darker:  lighten($gray-base, 13.5%); // #222
-// $gray-dark:    lighten($gray-base, 20.0%); // #333
-// $gray:         lighten($gray-base, 33.5%); // #555
-// $gray-light:   lighten($gray-base, 46.7%); // #777
-// $gray-lighter: lighten($gray-base, 93.5%); // #eee
+// $gray-base:    #000 !default;
+// $gray-darker:  lighten($gray-base, 13.5%) !default; // #222
+// $gray-dark:    lighten($gray-base, 20.0%) !default; // #333
+// $gray:         lighten($gray-base, 33.5%) !default; // #555
+// $gray-light:   lighten($gray-base, 46.7%) !default; // #777
+// $gray-lighter: lighten($gray-base, 93.5%) !default; // #eee
 //
-// $brand-primary: darken(#428bca, 6.5%); // #337ab7 (primary buttons, links, and active elements)
-// $brand-success: #5cb85c;
-// $brand-info:    #5bc0de;
-// $brand-warning: #f0ad4e;
-// $brand-danger:  #d9534f;
+// $brand-primary: darken(#428bca, 6.5%) !default; // #337ab7 (primary buttons, links, and active elements)
+// $brand-success: #5cb85c !default;
+// $brand-info:    #5bc0de !default;
+// $brand-warning: #f0ad4e !default;
+// $brand-danger:  #d9534f !default;
 
-// $list-group-border:  #ddd; // Borders on menus and sidebars
+// $list-group-border:  #ddd !default; // Borders on menus and sidebars
 
-// $text-color:            $gray-dark;
-// $link-color:            $brand-primary;
-// $link-hover-color:      darken($link-color, 15%);
+// $text-color:            $gray-dark !default;
+// $link-color:            $brand-primary !default;
+// $link-hover-color:      darken($link-color, 15%) !default;
 
 // Define colors for form feedback states and, by default, alerts.
-// $state-success-text:             #3c763d;
-// $state-success-bg:               #dff0d8;
-// $state-success-border:           darken(adjust-hue($state-success-bg, -10), 5%);
+// $state-success-text:             #3c763d !default;
+// $state-success-bg:               #dff0d8 !default;
+// $state-success-border:           darken(adjust-hue($state-success-bg, -10), 5%) !default;
 //
-// $state-info-text:                #31708f;
-// $state-info-bg:                  #d9edf7;
-// $state-info-border:              darken(adjust-hue($state-info-bg, -10), 7%);
+// $state-info-text:                #31708f !default;
+// $state-info-bg:                  #d9edf7 !default;
+// $state-info-border:              darken(adjust-hue($state-info-bg, -10), 7%) !default;
 //
-// $state-warning-text:             #8a6d3b;
-// $state-warning-bg:               #fcf8e3;
-// $state-warning-border:           darken(adjust-hue($state-warning-bg, -10), 5%);
+// $state-warning-text:             #8a6d3b !default;
+// $state-warning-bg:               #fcf8e3 !default;
+// $state-warning-border:           darken(adjust-hue($state-warning-bg, -10), 5%) !default;
 //
-// $state-danger-text:              #a94442;
-// $state-danger-bg:                #f2dede;
-// $state-danger-border:            darken(adjust-hue($state-danger-bg, -10), 5%);
+// $state-danger-text:              #a94442 !default;
+// $state-danger-bg:                #f2dede !default;
+// $state-danger-border:            darken(adjust-hue($state-danger-bg, -10), 5%) !default;
diff --git a/themes/sandal/scss/colors.scss b/themes/sandal/scss/colors.scss
index 6eb6c5f569d3cf1ec4551487b3317564e388c54d..17de5ebb4071c141126be6e58c2118a3e792152d 100644
--- a/themes/sandal/scss/colors.scss
+++ b/themes/sandal/scss/colors.scss
@@ -1,50 +1,50 @@
 @import 'vendor/tachyons-colors'; // Import colors from the tachyons library
 
 /* Material Colors can be found here: https://material.io/guidelines/style/color.html */
-$brand-primary: #1976d2; /* Material Blue 700 */
-$brand-secondary: #ff6d00; /* Material Orange A700 */
-
-$header-bg: #607d8b; /* Material Blue Grey 500 */
-$header-light: #cfd8dc; /* Material Blue Grey 100 */
-
-$action-color: $brand-primary;
-$action-hover-bg: $white;
-$action-hover-color: $black;
-$passive-icon-color: $gray;
-$highlighter-color: lighten(#FF0, 20%);
-
-$search-row-bg: $white;
-$search-row-bg-alt: $light-gray;
-$search-row-bg-hover: $lightest-blue;
-$search-row-selected-bg: $brand-primary;
-$search-row-selected-color: $white;
-
-$sidebar-title-bg: $white;
-$sidebar-title-color: $near-black;
-$sidebar-title-icon-color: $light-gray;
-$sidebar-item-bg: $white;
-$sidebar-item-color: $black;
-$sidebar-item-hover-bg: $lightest-blue;
-$sidebar-item-badge: $gray;
-$sidebar-active-bg: $brand-secondary;
-$sidebar-active-color: $white;
+$brand-primary: #1976d2 !default; /* Material Blue 700 */
+$brand-secondary: #ff6d00 !default; /* Material Orange A700 */
+
+$header-bg: #607d8b !default; /* Material Blue Grey 500 */
+$header-light: #cfd8dc !default; /* Material Blue Grey 100 */
+
+$action-color: $brand-primary !default;
+$action-hover-bg: $white !default;
+$action-hover-color: $black !default;
+$passive-icon-color: $gray !default;
+$highlighter-color: lighten(#FF0, 20%) !default;
+
+$search-row-bg: $white !default;
+$search-row-bg-alt: $light-gray !default;
+$search-row-bg-hover: $lightest-blue !default;
+$search-row-selected-bg: $brand-primary !default;
+$search-row-selected-color: $white !default;
+
+$sidebar-title-bg: $white !default;
+$sidebar-title-color: $near-black !default;
+$sidebar-title-icon-color: $light-gray !default;
+$sidebar-item-bg: $white !default;
+$sidebar-item-color: $black !default;
+$sidebar-item-hover-bg: $lightest-blue !default;
+$sidebar-item-badge: $gray !default;
+$sidebar-active-bg: $brand-secondary !default;
+$sidebar-active-color: $white !default;
 
 /* Bootstrap variable changes */
 
-$link-color: #1565c0; /* Material Blue 800 */
-$link-color-hover: #0d47a1; /* Material Blue 900 */
+$link-color: #1565c0 !default; /* Material Blue 800 */
+$link-color-hover: #0d47a1 !default; /* Material Blue 900 */
 
-$input-border:              $light-silver;
-$input-color:               $dark-gray;
-$btn-default-bg:            $light-gray;
-$btn-default-color:         $near-black;
-$btn-primary-bg:            $action-color;
+$input-border:              $light-silver !default;
+$input-color:               $dark-gray !default;
+$btn-default-bg:            $light-gray !default;
+$btn-default-color:         $near-black !default;
+$btn-primary-bg:            $action-color !default;
 
-$input-border-radius:         .25rem;
+$input-border-radius:         .25rem !default;
 
-$autocomplete-hover-bg:     $header-light;
-$dropdown-link-hover-bg:    $header-light;
-$dropdown-link-hover-color: $black;
-$list-group-active-bg:      $brand-secondary;
-$table-bg-hover:            $header-light;
-$pagination-color:          $header-bg;
+$autocomplete-hover-bg:     $header-light !default;
+$dropdown-link-hover-bg:    $header-light !default;
+$dropdown-link-hover-color: $black !default;
+$list-group-active-bg:      $brand-secondary !default;
+$table-bg-hover:            $header-light !default;
+$pagination-color:          $header-bg !default;
diff --git a/themes/sandal/scss/common.scss b/themes/sandal/scss/common.scss
index 0ed8798050c0a4003f1c1e0271e0ad2a0da9b03c..f835a95b6db203c302fcfe5627b3ead5159e8153 100644
--- a/themes/sandal/scss/common.scss
+++ b/themes/sandal/scss/common.scss
@@ -1,6 +1,6 @@
 /* ------ Border radius changes ------ */
-$list-group-border-radius: 0;
-$border-radius-large: 0; // modal
+$list-group-border-radius: 0 !default;
+$border-radius-large: 0 !default; // modal
 
 /* ------ Common element changes ------ */
 .help-block {
@@ -99,8 +99,8 @@ select.form-control {
 
 .label { font-weight: 400; }
 
-$pagination-border: transparent;
-$pagination-hover-border: transparent;
+$pagination-border: transparent !default;
+$pagination-hover-border: transparent !default;
 .pagination {
   @include clearfix();
   display: table;
diff --git a/themes/sandal/scss/variables.scss b/themes/sandal/scss/variables.scss
index 294c2fcb7b78c296d79ef80d2431047eeddc5ab2..8e18e8bbbd73663bc9fa2cb937470343265b8f3c 100644
--- a/themes/sandal/scss/variables.scss
+++ b/themes/sandal/scss/variables.scss
@@ -1,13 +1,13 @@
-$reduced-font-size: 14px;
-$img-path: "../../sandal/images/";
+$reduced-font-size: 14px !default;
+$img-path: "../../sandal/images/" !default;
 
-$banner-height: 60px;
-$banner-height-sm: 40px;
-$search-tab-height: 2rem;
+$banner-height: 60px !default;
+$banner-height-sm: 40px !default;
+$search-tab-height: 2rem !default;
 
-$result-checkbox-width: 28px;
-$result-checkbox-height: 80px;
-$result-sm-icon-size: 1.5rem;
+$result-checkbox-width: 28px !default;
+$result-checkbox-height: 80px !default;
+$result-sm-icon-size: 1.5rem !default;
 
 /* ------ Mixins ------ */
 @mixin full-width(){ // Break out of the container