add style for disabled sliders

i use `` for output values

disabled sliders are read-only, and should have a different style than writable sliders

for example:

```css
/* disable color + cursor */
input[type=range][disabled]::-webkit-slider-thumb {
background: grey;
cursor: default;
}
input[type=range][disabled]::-webkit-slider-runnable-track {
cursor: default;
}

/* disable hover color */
input[type=range][disabled]:hover::-webkit-slider-runnable-track {
background: white;
}
input[type=range][disabled]:hover::-webkit-slider-thumb {
background: grey;
}

/* hover color */
input[type=range]:hover::-webkit-slider-runnable-track {
background: lightgray;
}
```