Add loading indicator

style/loading.scss

@@ -0,0 +1,59 @@
+@import "theme.scss";
+
+.loading-page {
+	display: flex;
+	justify-content: center;
+	align-items: center;
+	height: 100%;
+}
+
+.loading {
+	position: relative;
+	width: 10px;
+	height: 10px;
+	border-radius: 5px;
+	margin: 10px;
+	background-color: $accent-color;
+	color: $accent-color;
+	animation: dot-flashing 1s infinite linear alternate;
+	animation-delay: 0.5s;
+}
+
+.loading::before, .loading::after {
+	content: "";
+	display: inline-block;
+	position: absolute;
+	top: 0;
+}
+
+.loading::before {
+	left: -15px;
+	width: 10px;
+	height: 10px;
+	border-radius: 5px;
+	background-color: $accent-color;
+	color: $accent-color;
+	animation: dot-flashing 1s infinite alternate;
+	animation-delay: 0s;
+}
+
+.loading::after {
+	left: 15px;
+	width: 10px;
+	height: 10px;
+	border-radius: 5px;
+	background-color: $accent-color;
+	color: $accent-color;
+	animation: dot-flashing 1s infinite alternate;
+	animation-delay: 1s;
+}
+
+@keyframes dot-flashing {
+	0% {
+		background-color: $accent-color;
+	}
+
+	50%, 100% {
+		background-color: $controls-hover-color;
+	}
+}

style/main.scss

@@ -13,6 +13,7 @@
 @import 'upload.scss';
 @import 'error.scss';
 @import 'song_list.scss';
+@import 'loading.scss';
 
 body {
   font-family: sans-serif;