chore: Add SPDX header

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

css/activity.css

@@ -1,3 +1,7 @@
+/**
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
 .activitymessage .visualdiff ins {
 	background-color: rgba(70, 186, 97, 0.2);
 	text-decoration: none;

css/collections.css

@@ -1,3 +1,7 @@
+/**
+ * SPDX-FileCopyrightText: 2019 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
 .resource-type-deck img {
 	opacity: 0.4 !important;
 }

css/deck.css

@@ -1,3 +1,7 @@
+/**
+ * SPDX-FileCopyrightText: 2016 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
 .icon-deck {
 	background-image: url(../img/deck-dark.svg);
 	filter: var(--background-invert-if-dark);

css/print.scss

@@ -1,3 +1,7 @@
+/*!
+ * SPDX-FileCopyrightText: 2018 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
 @media print {
 	/* hide stuff */
 	#body-user {