Accessibility

What a deck does with no extra work:

• Deck.Root is a region with aria-roledescription="carousel", named by your aria-label.
• Each slide is a group with aria-roledescription="slide", labelled "n of m".
• Prev, Next, the dots and the toggle are native buttons with names. Dots are a labelled group of buttons with aria-current, not tabs, since a dot can stand for a page of several slides.
• A polite live region announces "Slide n of m" after a move the user makes. It is off while autoplay rotates the deck.
• No slide is hidden or inert for being off-screen. Tabbing into an off-screen slide scrolls it into view natively, and snap settles it. During a move, the deck goes to the snap point of that slide's page instead.
• The viewport is focusable, so the arrow keys, Page Up, Page Down, Home and End scroll it.
• Loop copies are inert and aria-hidden, so they are never focused or announced.
• Under reduced motion, a move carouseldeck starts (Prev, Next, a dot, scrollTo, a new index, a drag's release) jumps to its snap point instead of scrolling smoothly. Autoplay starts stopped, fade cuts, and curve stays flat.

There is one exception. In a fade deck, every slide but the focal one is inert, as it sits under the focal one. Keyboard and screen reader users reach the slides through Prev, Next, Dots and the arrow keys.