var is_keyboard = false;
var is_landscape = false;
var initial_screen_size = window.innerHeight;

/* Android */
window.addEventListener("resize", function() {
    is_keyboard = (window.innerHeight < initial_screen_size);
    is_landscape = (screen.height < screen.width);

    updateViews();
}, false);

/* iOS */
$("input").bind("focus blur",function() {
    $(window).scrollTop(10);
    is_keyboard = $(window).scrollTop() > 0;
    $(window).scrollTop(0);
    updateViews();
});

function updateViews() {
    $("li").hide();
    if (is_keyboard) {
        $("#logo").hide();
        if (is_landscape) {
            $("li").slice(0, 2).show();
        }
        else {
            $("li").slice(0, 4).show();
        }
    }
    else {
        $("#logo").show();
        $("li").show();
    }
}

<div id="logo">Logo</div>
<input type="text"><input type="submit" value="search">
<ul>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
    <li>Item</li>
</ul>