diff --git a/Perfectly centering pixels is tricky.md b/Perfectly centering pixels is tricky.md
new file mode 100644
index 0000000..c3b2cb0
--- /dev/null
+++ b/Perfectly centering pixels is tricky.md
@@ -0,0 +1,11 @@
+# Perfectly centering pixels is tricky
+
+To perfectly center a container (like a `
`) inside another container, both containers' sizes must have the same parity, in other words, both sizes must be either even or odd, in the direction of centering.
+
+Same thing happens if many containers are nested, and each of them need to be centered across its parent, they all need to be even or odd.
+
+Font makes things trickier. Let's suppose you want to center vertically a text inside an even container, and you may think that choosing an even `font-size` will do the trick, but if you choose a size like `14px` and a `line height` different than `1` or `2` (both options are unpleasant in most cases), then text's effective height will be odd, and text `height` parity will mismatch with its parent and will be impossible to center.
+
+## What led to learning this
+
+- Podcast: Full Stack Radio: 135: Lessons Learned Building Tailwind UI