Added custom error pages

src/static/pretixbase/less/cachedfiles.less

@@ -1,11 +1,9 @@
 @import "../../bootstrap/less/bootstrap.less";
 @import "../../fontawesome/less/font-awesome.less";
-@import "../../lightbox/css/lightbox.css";
+@import "colors.less";
 
 @fa-font-path: "../../fontawesome/fonts";
 
-@brand-primary: #8E44B3;
-
 body {
     background: #ececec;
     text-align: center;

src/static/pretixbase/less/colors.less

@@ -0,0 +1 @@
+@brand-primary: #8E44B3;

src/static/pretixbase/less/error.less

@@ -0,0 +1,16 @@
+@import "../../bootstrap/less/bootstrap.less";
+@import "../../fontawesome/less/font-awesome.less";
+@import "colors.less";
+
+@fa-font-path: "../../fontawesome/fonts";
+
+body {
+    background: #ececec;
+    text-align: center;
+    padding: 50px 0;
+}
+
+.big-icon {
+    font-size: 200px;
+    color: @brand-primary;
+}

src/static/pretixpresale/less/main.less

@@ -2,8 +2,7 @@
 @import "../../fontawesome/less/font-awesome.less";
 @import "../../lightbox/css/lightbox.css";
 @fa-font-path: "../../fontawesome/fonts";
-
-@brand-primary: #8E44B3;
+@import "../../pretixbase/less/colors.less";
 
 @import "event.less";
 @import "forms.less";