The Slider labels (<span> elements) are enclosed inside the Slider ticks (<li> elements). The size of the ticks is always calculated, depending on the Slider size and the defined largeStep and smallStep. The labels can have arbitrary size, depending on the character count, that's why they can overflow the tick elements by design.
You can avoid the observed layout issue in two ways - enable the Slider buttons, or apply a suitable side padding to the Slider container. The size of the Slider labels can depend on the font size, that's why it is better to set the padding in em units, so that it depends on the font size too.
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