一场小赛马，两种理解。

Create a single-file, playable browser horse racing simulator/game.

Output ONE file named index.html — all CSS inline in <style>, all JS inline in <script>. No external dependencies, no build step, no image/audio assets from the internet (draw everything with Canvas 2D or CSS/SVG — simple geometric horse shapes are fine, this is not about art quality).

## Core gameplay (all of this must actually work, not just be described):
1. A **top-down or side-view race track** rendered on an HTML5 `<canvas>` element, with lane dividers and a clear start and finish line.
2. **6 horses** (or your choice of 4-8), each rendered as a simple distinct-colored shape/sprite (a colored oval/rectangle with a number is fine), each running in its own lane.
3. Each horse has a hidden "true speed" stat with some randomness applied per-tick (e.g. base speed +/- random variance each frame) so races have different outcomes each time — this must use real randomness (`Math.random()`), not a scripted/fixed outcome.
4. A **"Start Race" button** that begins the simulation; horses visibly animate/move across the canvas toward the finish line using `requestAnimationFrame` (real animation loop, not a single instant jump).
5. **Betting mechanic**: before the race starts, let the user pick one horse to bet on (click to select) and see fake odds displayed per horse (odds can be randomly generated per race, or based on relative speed stats — your choice, just make it feel real).
6. When the race finishes, show a results screen: finishing order (1st/2nd/3rd/etc), and whether the user's bet won, with a simple fake "winnings" number if they bet correctly.
7. A "Race Again" button that resets everything and lets you run a new race with fresh random odds/outcome.

## Polish (attempt these, but core gameplay above takes priority):
- Simple camera/canvas effects: a subtle screen shake or speed-line effect in the final stretch, horses jockeying for position visibly (not just moving in fixed lanes with no overtaking — try to have their canvas x-position actually reflect relative progress so a trailing horse can visually pass another).
- A basic commentary/log area that prints simple text updates during the race (e.g. "Horse 3 takes the lead!") triggered by actual position changes in your simulation, not randomly generated flavor text.
- Sound is optional and low priority — skip it if it adds complexity, this is not a requirement.

## Style: doesn't need to be fancy — a clean, readable UI is enough (track green/brown tones, clear typography for odds/results). Prioritize the simulation actually working and being playable over visual polish.

Write only index.html. No commentary, just create the file.