diff --git a/websites/cses.fi.css b/websites/cses.fi.css
new file mode 100644
index 00000000..7f0a20f3
--- /dev/null
+++ b/websites/cses.fi.css
@@ -0,0 +1,183 @@
+/* cses-background */
+html,
+body {
+  background: transparent !important;
+  color-scheme: dark !important;
+}
+
+/* global text */
+body,
+p,
+li,
+td,
+th,
+h1,
+h2,
+h3,
+h4,
+label,
+strong,
+b {
+  color: #e8e8e8 !important;
+}
+
+/* links */
+a {
+  color: #6fb4ff !important;
+}
+
+a:hover {
+  color: #8fc7ff !important;
+}
+
+/* header */
+.header {
+  background: rgba(10, 10, 10, 0.35) !important;
+
+  backdrop-filter: blur(20px) !important;
+  -webkit-backdrop-filter: blur(20px) !important;
+
+  border-bottom: 1px solid rgba(255, 255, 255, 0.08) !important;
+
+  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.25) !important;
+}
+
+/* content containers */
+.content,
+.boxes > div {
+  background: rgba(15, 15, 15, 0.45) !important;
+
+  backdrop-filter: blur(12px) !important;
+  -webkit-backdrop-filter: blur(12px) !important;
+
+  border: 1px solid rgba(255, 255, 255, 0.06) !important;
+
+  border-radius: 12px !important;
+
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12) !important;
+}
+
+/* sidebar */
+.sidebar {
+  background: rgba(15, 15, 15, 0.55) !important;
+
+  backdrop-filter: blur(12px) !important;
+  -webkit-backdrop-filter: blur(12px) !important;
+
+  border: 1px solid rgba(255, 255, 255, 0.06) !important;
+
+  border-radius: 12px !important;
+
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.12) !important;
+
+  margin-left: 1rem !important;
+}
+
+/* breathing room */
+.nav {
+  margin-top: 0.75rem !important;
+  margin-bottom: 1.25rem !important;
+}
+
+.content {
+  margin-top: 1rem !important;
+}
+
+.sidebar {
+  margin-top: 1rem !important;
+}
+
+/* nav tabs */
+.nav a,
+.nav .current {
+  padding: 0.35rem 0.75rem !important;
+  border-radius: 8px !important;
+}
+
+/* task rows */
+.task-list li {
+  transition:
+    background-color 150ms ease,
+    transform 150ms ease !important;
+}
+
+.task-list li:hover {
+  background: rgba(255, 255, 255, 0.06) !important;
+}
+
+/* inputs */
+input[type="text"],
+input[type="password"],
+textarea,
+select {
+  background: rgba(20, 20, 20, 0.35) !important;
+
+  color: #e8e8e8 !important;
+
+  border: 1px solid rgba(255, 255, 255, 0.08) !important;
+
+  border-radius: 8px !important;
+
+  backdrop-filter: blur(8px) !important;
+  -webkit-backdrop-filter: blur(8px) !important;
+}
+
+/* buttons */
+button,
+input[type="submit"],
+input[type="button"] {
+  background: rgba(255, 255, 255, 0.08) !important;
+
+  color: #e8e8e8 !important;
+
+  border: 1px solid rgba(255, 255, 255, 0.12) !important;
+
+  border-radius: 8px !important;
+
+  padding: 0.5rem 1rem !important;
+
+  backdrop-filter: blur(8px) !important;
+  -webkit-backdrop-filter: blur(8px) !important;
+
+  transition:
+    background-color 150ms ease,
+    border-color 150ms ease !important;
+}
+
+button:hover,
+input[type="submit"]:hover,
+input[type="button"]:hover {
+  background: rgba(255, 255, 255, 0.14) !important;
+
+  border-color: rgba(255, 255, 255, 0.2) !important;
+}
+
+/* file picker */
+input[type="file"] {
+  color: #e8e8e8 !important;
+}
+
+/* tables */
+table {
+  background: transparent !important;
+}
+
+tbody tr:nth-child(even) {
+  background: rgba(255, 255, 255, 0.03) !important;
+}
+
+th {
+  background: rgba(255, 255, 255, 0.05) !important;
+}
+
+/* code & examples */
+pre,
+code {
+  background: rgba(255, 255, 255, 0.04) !important;
+  border-radius: 6px !important;
+}
+
+/* separators */
+hr {
+  opacity: 0.25 !important;
+}