function show_content_block(blockid) {
    var block1 = document.getElementById('content_block_1');
    var block2 = document.getElementById('content_block_2');
    var tab1 = document.getElementById('content_tab_1');
    var tab2 = document.getElementById('content_tab_2');

    block1.style.display = 'none';
    block2.style.display = 'none';
    tab1.className = '';
    tab2.className = '';

    if (blockid == 1) {
        block1.style.display = 'block';
		tab1.className = 'on';
    }

    if (blockid == 2) {
        block2.style.display = 'block';
		tab2.className = 'on';
    }

}