Initial commit: site code, layouts, content (images added separately)

Fixes duplicate placeholder cover image on the 3 newest blog posts,
broken aspect-ratio classes on the albums listing page, and a
non-responsive fixed sidebar on the chat page.

content/blog/post-4.md

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+---
+title: "VPD Explained for Complete Beginners"
+date: 2024-03-20T10:00:00Z
+image: "/images/IMG_9449.jpeg"
+summary: "Temperature and humidity are connected. Learn how to hit the sweet spot."
+---
+
+VPD stands for Vapor Pressure Deficit. Think of it as the air's drying power.
+
+If the air is too dry (high VPD), plants sweat too much and slam their stomata to save water. Growth stops.
+If the air is too humid (low VPD), they barely sweat. No water movement means no calcium uptake.
+
+You want the Goldilocks zone. For early veg, aim around 0.8 kPa. For flower, push 1.2–1.4 kPa.