Here is the modified HTML code that hides the mute button like the settings button, with auto-hide functionality.
```html
Silent Flow | Ambient Wave Visualizer
--:--:--
--
âī¸
đ Theme
âąī¸ Rec Duration
âĒ Ready
đī¸ Allow microphone to visualize live waves
Click to start
đĩ Live Audio Visualizer
```