major redesign: move to rounded and extra spaceous UI

+ fix `play next` bug
+ add new folder banner image
+ add new now playing component
+ move to gray4 for accent color
+ increase image sizes, for clean UI

src/assets/scss/_variables.scss

@@ -39,7 +39,7 @@ $indigo: #5e5ce6;
 $teal: rgb(64, 200, 224);
 
 $primary: $gray4;
-$accent: $red;
+$accent: $gray1;
 $secondary: $gray5;
 $cta: $blue;
 $danger: $red;
@@ -48,7 +48,7 @@ $context: $gray;
 
 // SVG COLORS
 $default: $accent;
-$track-btn-svg: $red;
+$track-btn-svg: $accent;
 $side-nav-svg: $red;