Fix postcss warnings about old gradient syntax and justify-content: start

front/src/style/components/_player.scss

@@ -81,7 +81,7 @@
   .track-controls {
     display: flex;
     align-items: center;
-    justify-content: start;
+    justify-content: flex-start;
     flex-grow: 1;
     .image {
       padding: 0.5em;

front/src/style/globals/_utils.scss

@@ -73,7 +73,7 @@ a {
   &:not(.expanded) {
     overflow: hidden;
     max-height: 15vh;
-    background: linear-gradient(top, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 90%, rgba(0, 0, 0, 0.3) 100%);
+    background: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 90%, rgba(0, 0, 0, 0.3) 100%);
   }
 }