Jen Simmons, who works on Safari's WebKit engine at Apple, said Apple is looking for a way to let websites use more of the iPhone Duo's 5.4-inch outer screen. Safari puts its controls in a column down the right side to save height, and web pages can't draw behind them. That leaves a page about 382 CSS pixels wide, the unit web designers measure in, when you hold the phone upright. Safari tints the leftover strip to match the page.
A setting called viewport-fit=cover already lets a site fill the whole screen, but many sites don't leave safe margins on every edge, so Simmons says a button or a headline could end up hidden under the controls. Apple wants something sturdier and simpler, and Simmons asked web developers for ideas on the WebKit blog. There's no date for a fix. Until then, long pages are easier to read on the inner screen. PDFs already make good use of the fold: open one in Safari, fold the phone partway like a paperback, and you get two pages side by side.