[Bug] Buttons and inputs overflow the tool panel on narrow widths #56

On narrow widths, a few controls break out of their card:

• Split, "Range Selection" row: the Apply button is pushed outside the card.
• Split, desktop sidebar: the Preview and Share buttons overflow, and Share sticks out past the card's right edge.
• Split, selected-count row: the "Selected" label and the page count are vertically misaligned.

Steps to reproduce

1. Open Split (/#/split) and load a PDF.
2. In a narrow window, or in the desktop right-hand panel, the Apply button leaves the card and the Preview and Share buttons overflow.

Root cause

The flex children (flex-1 inputs and buttons) keep the default min-width: auto, so they do not shrink and push the adjacent button out instead. The Preview and Share buttons also use md:text-xl, which is too wide for the roughly 233px sidebar.

Screenshots