3D pixel look follows the window size

The 3D resolution setting refers to a window 1080 device pixels high; smaller windows use a
proportionally smaller divisor (1/1 stays full resolution). Settings show the divisor in effect.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

DESIGN.md

@@ -9,7 +9,7 @@ An original dungeon management game (genre: dungeon building & defence) that run
 - All UI windows use **CP437 frames** (single lines for panels, double lines for dialogs); **all bars are CP437 block characters** (█ ▌ ░)
 - Text only in **fixed integer sizes**: 1×, 2× and 4× the 6×8 glyph size, times an integer **interface factor** (automatic from the device resolution, or 1×–4× in the settings)
 - The interface is drawn in **device pixels** (high DPI) and laid out on the **character grid**, so every font pixel has exactly the same size
-- **3D resolution** setting: the world can be rendered at 1/1 down to 1/16 resolution and scaled up by exactly that factor (pixel look); the interface stays sharp
+- **3D resolution** setting: the world can be rendered at 1/1 down to 1/16 resolution and scaled up by exactly that factor (pixel look); the setting refers to a window 1080 device pixels high and scales with the window size, so the 3D pixels keep their size relative to the window; the interface stays sharp
 - Sound: event system + macroquad audio prepared (volume, mute key M); sounds will be generated later
 - Languages: all in-game texts live in **language files** (`lang/*.lang`, key = text); English is the reference/fallback, German included, more can be added. The language is chosen on first start and stored in the browser.
 - Repository language: **English** (code, comments, docs, commit messages)