function teaserNext() {
    if((current_teaser + 1) < teasers_count) {
        showTeaser((current_teaser + 1));   
    }
}

function teaserPrev() {
    if((current_teaser) > 0) {
        showTeaser((current_teaser - 1));
    }
}

function showTeaser(id) {
    if(id != current_teaser) {
        $('#teaser' + current_teaser).fadeOut(300, fadeInTeaser(id));
        
        document.getElementById('tpagelink' + current_teaser).style.color = '#99D5EE';
        document.getElementById('tpagelink' + current_teaser).style.textDecoration = 'underline';
        document.getElementById('tpagelink' + current_teaser).style.fontWeight = 'normal';
        if(current_teaser != 0) {
            document.getElementById('teaserback' + current_teaser).style.display = 'block';
            document.getElementById('teaserback_active' + current_teaser).style.display = 'none';
        }
        
        document.getElementById('tpagelink' + id).style.color = '#fff';
        document.getElementById('tpagelink' + id).style.textDecoration = 'none';
        document.getElementById('tpagelink' + id).style.fontWeight = 'bold';
        if(id != 0) {
            document.getElementById('teaserback' + id).style.display = 'none';
            document.getElementById('teaserback_active' + id).style.display = 'block';
        }
        
        current_teaser = id;
    }
}

function fadeInTeaser(id) {
    $('#teaser' + id).fadeIn(300); 
}

function pressLeft() {
    document.getElementById('teaser_left').style.backgroundImage = 'http://task2.netangels.ru/images/button_left.jpg';
}

function pressRight() {
    document.getElementById('teaser_right').style.backgroundImage = 'http://task2.netangels.ru/images/button_right.jpg';
}

function unpressLeft() {
    document.getElementById('teaser_left').style.backgroundImage = '';
}

function unpressRight() {
    document.getElementById('teaser_right').style.backgroundImage = '';
}

function pressContacts() {
    document.getElementById('contacts_button').src = 'http://task2.netangels.ru/images/contacts_pressed.jpg';
}

function unpressContacts() {
    document.getElementById('contacts_button').src = 'http://task2.netangels.ru/images/send_button.gif';
}