[Frontend] Styling for controls

Fixes #1324
CSS, markup, WIP adding reset button

platform/commonUI/general/res/sass/_global.scss

@@ -175,6 +175,11 @@ a.disabled {
 	display: none !important;
 }
 
+.hide-nice {
+    opacity: 0;
+    pointer-events: none;
+}
+
 .off {
     visibility: hidden;
     opacity: 0;

platform/commonUI/general/res/sass/controls/_controls.scss

@@ -122,17 +122,18 @@
     // Default position is upper right
     $p: $interiorMargin;
     position: absolute;
-    top: $p; right: $p; bottom: auto; left: $p;
+    top: $p; right: $p; bottom: auto;
     text-align: right;
     z-index: 5;
 }
 
 .s-local-controls {
+    @include trans-prop-nice(opacity);
     font-size: 0.7rem;
     &.s-wrapper-transluc {
         // Semi-opaque wrapper to visually distinguish a control
         // from the background
-        background: rgba($colorBodyFg, 0.2);
+        background: rgba($colorTransLucBg, 0.5);
         box-sizing: border-box;
         border-radius: $controlCr;
     }

platform/commonUI/general/res/sass/features/_imagery.scss

@@ -1,5 +1,6 @@
 .l-image-main-wrapper,
-.l-image-thumbs-wrapper {
+.l-image-thumbs-wrapper,
+.image-main {
 	@include absPosDefault(0, false);
 }
 
@@ -32,7 +33,7 @@
 
 /*************************************** MAIN IMAGE */
 
-.l-image-main,
+.image-main,
 .l-image-thumb-item .l-thumb {
 	background-size: contain;
 	background-position: center;

platform/commonUI/themes/espresso/res/sass/_constants.scss

@@ -50,6 +50,7 @@ $sliderKnobW: 15px;
 $sliderKnobR: 2px;
 $timeControllerToiLineColor: #00c2ff;
 $timeControllerToiLineColorHov: #fff;
+$colorTransLucBg: #666; // Used as a visual blocking element over variable backgrounds, like imagery
 
 // General Colors
 $colorAlt1: #ffc700;

platform/commonUI/themes/snow/res/sass/_constants.scss

@@ -50,6 +50,7 @@ $sliderKnobW: 15px;
 $sliderKnobR: 2px;
 $timeControllerToiLineColor: $colorBodyFg;
 $timeControllerToiLineColorHov: #0052b5;
+$colorTransLucBg: #666; // Used as a visual blocking element over variable backgrounds, like imagery
 
 // General Colors
 $colorAlt1: #776ba2;