fix: remove scroll bar

[yanCode]

in toast-notification-0, if you wait until the toast bar is gone, you can see it creates a scroll bar in the right side of the browser. this is because there is bottom: 1.5rem;, but also transform: translateY(1.875rem);, which moves the .notification out of the view point, to fix this issue, the value of translateY shouldn't exceed bottom. I use variable --bottom-distance: 1.5rem; to unify the 2 values.