added icons and moved to the css directory

css/list_add.css

@@ -0,0 +1,55 @@
+@charset "UTF-8";
+
+i.icon.list.add {
+	box-sizing: border-box;
+	position: relative;
+	display: block;
+	width: 12px;
+	height: 6px;
+	border-top: 0 solid transparent;
+	border-bottom: 2px solid transparent;
+	box-shadow:
+		inset 0 -2px 0,
+		-2px 4px 0 -2px,
+		0 -2px 0 0;
+}
+
+i.icon.list.add.small {
+	width: 10px;
+	box-shadow:
+		inset 0 -2px 0,
+		-1px 3px 0 -1px,
+		0 -2px 0 0;
+}
+
+i.icon.list.add::after,
+i.icon.list.add::before {
+	content: "";
+	display: block;
+	box-sizing: border-box;
+	position: absolute;
+	width: 10px;
+	height: 2px;
+	background: currentColor;
+	top: 6px;
+	right: -8px;
+}
+
+i.icon.list.add.small::after,
+i.icon.list.add.small::before {
+	width: 8px;
+}
+
+i.icon.list.add::before {
+	width: 2px;
+	height: 10px;
+	top: 2px;
+	right: -4px;
+}
+
+i.icon.list.add.small::before {
+	width: 2px;
+	height: 8px;
+	top: 3px;
+	right: -5px;
+}