Moved from Sass to CSS with custom properties, allowing for dynamic theme changes.

src/web/stylesheets/preloader.css

@@ -0,0 +1,135 @@
+/**
+ * Preloader styles
+ *
+ * @author n1474335 [n1474335@gmail.com]
+ * @copyright Crown Copyright 2017
+ * @license Apache-2.0
+ */
+
+#loader-wrapper {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    z-index: 1000;
+    background-color: var(--secondary-border-colour);
+}
+
+#preloader {
+    display: block;
+    position: relative;
+    left: 50%;
+    top: 50%;
+    width: 150px;
+    height: 150px;
+    margin: -75px 0 0 -75px;
+
+    border: 3px solid transparent;
+    border-top-color: #3498db;
+    border-radius: 50%;
+    z-index: 1500;
+
+    animation: spin 2s linear infinite;
+}
+
+#preloader:before,
+#preloader:after {
+    content: "";
+    position: absolute;
+    top: 5px;
+    left: 5px;
+    right: 5px;
+    bottom: 5px;
+    border: 3px solid transparent;
+    border-radius: 50%;
+}
+
+#preloader:before {
+    border-top-color: #e74c3c;
+    animation: spin 3s linear infinite;
+}
+
+#preloader:after {
+    border-top-color: #f9c922;
+    animation: spin 1.5s linear infinite;
+}
+
+
+/* Loaded */
+.loaded #preloader {
+    opacity: 0;
+    transition: all 0.3s ease-out;
+}
+
+.loaded #loader-wrapper {
+    opacity: 0;
+    transition: all 0.5s 0.3s ease-out;
+}
+
+.loaded #rec-list li {
+	animation: bump 0.7s cubic-bezier(0.7, 0, 0.3, 1) both;
+}
+
+.loaded #content-wrapper {
+	animation-delay: 0.10s;
+}
+
+.loaded #rec-list li:first-child {
+	animation-delay: 0.20s;
+}
+
+.loaded #rec-list li:nth-child(2) {
+	animation-delay: 0.25s;
+}
+
+.loaded #rec-list li:nth-child(3) {
+	animation-delay: 0.30s;
+}
+
+.loaded #rec-list li:nth-child(4) {
+	animation-delay: 0.35s;
+}
+
+.loaded #rec-list li:nth-child(5) {
+	animation-delay: 0.40s;
+}
+
+.loaded #rec-list li:nth-child(6) {
+	animation-delay: 0.45s;
+}
+
+.loaded #rec-list li:nth-child(7) {
+	animation-delay: 0.50s;
+}
+
+.loaded #rec-list li:nth-child(8) {
+	animation-delay: 0.55s;
+}
+
+.loaded #rec-list li:nth-child(9) {
+	animation-delay: 0.60s;
+}
+
+.loaded #rec-list li:nth-child(10) {
+	animation-delay: 0.65s;
+}
+
+
+/* Animations */
+
+@keyframes spin {
+    0%   {
+        transform: rotate(0deg);
+    }
+    100% {
+        transform: rotate(360deg);
+    }
+}
+
+@keyframes bump {
+	from {
+        opacity: 0;
+        transform: translate3d(0, 200px, 0);
+    }
+}