D3 Starter
A minimalist React application renders a smiling face in SVG using D3 v5, demonstrating basic shape creation and animation. The code builds circles for the head and eyes, a path for the mouth via `d3.arc()`, and rectangles for eyebrows within a group. A `transition().duration(1000)` animates the eyebrow group upward, while the static SVG elements use attributes like `cx`, `cy`, and `r`. The example highlights D3’s selection and append methods for constructing visual elements on a 960×500 canvas.