Controls
• Click empty legal triangle = add panel
• Shift+Click or Right Click = remove panel / symmetry group
• Hover existing tile = high-contrast delete preview
• Alt + Left Mouse Drag = rotate
• Alt + Middle Mouse Drag = pan / translate
• Alt + Scroll Up/Down = zoom in/out
• Ctrl/Cmd + Z = undo
• Ctrl/Cmd + Y or Ctrl/Cmd + Shift + Z = redo

Symmetry
• Symmetry axes use the current view angle snapped to the nearest 30° increment
• Presets only show Flat Grid and Vertical Grid because the triangle grid visually repeats
• Snap 30° rounds manual Alt-drag rotation to the closest 30° angle, including 60°, 90°, 120°, etc.
• Vertical means current screen vertical, horizontal means current screen horizontal

Connection rule
• Every tile must be connected by at least one full edge
• Vertex-only touching is illegal everywhere

Color modes
• Solid, Breathe, Rainbow, Color Wave, Random Tiles, Sparkle, and Aurora
• Animated modes preview live on the canvas

Persistence
• Layout auto-saves in your browser
• Reopening the page restores the last valid state