diff --git a/site/lib/lib.typ b/site/lib/lib.typ
new file mode 100644
index 0000000..0f462bd
--- /dev/null
+++ b/site/lib/lib.typ
@@ -0,0 +1,51 @@
+// #import "@preview/calepin:0.1.0" as calepin
+#import "@preview/hes-so-core:0.1.0"
+#import "@preview/frackable:0.2.0": *
+
+// #import "@preview/cetz:0.5.2"
+//
+// #let drawing(..args) = {
+//   let canvas = cetz.canvas(..args)
+//   context if target() == "html" {
+//     html.frame(canvas)
+//   } else {
+//     canvas
+//   }
+// }
+
+#let tag(body, fill: yellow, stroke: auto) = {
+  let stroke-color = if stroke == auto {
+    fill.darken(25%)
+  } else if type(stroke) == color {
+    stroke
+  } else if type(stroke) == stroke {
+    stroke.paint
+  } else {
+    fill.darken(25%)
+  }
+
+  let stroke-rule = if stroke == auto {
+    1pt + stroke-color
+  } else if type(stroke) == color {
+    1pt + stroke
+  } else {
+    stroke
+  }
+
+  context if target() == "html" {
+    let bg-hex = fill.to-hex()
+    let border-hex = stroke-color.to-hex()
+    html.elem("span", attrs: (
+      style: "display: inline-block; background-color: " + bg-hex
+        + "; border: 1px solid " + border-hex
+        + "; color: #1f2933; border-radius: 1em; padding: 0.2em 0.6em; font-size: 0.85em; font-weight: 500; line-height: 1.2;"
+    ))[#body]
+  } else {
+    box(
+      fill: fill,
+      stroke: stroke-rule,
+      radius: 1em,
+      inset: (x: 0.5em, y: 0.5em)
+    )[#body]
+  }
+}