lolpops,
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
dl {
margin-bottom:50px;
}
dl dt {
background:#5f9be3;
color:#fff;
float:left;
font-weight:bold;
margin-right:10px;
padding:5px;
width:100px;
}
dl dd {
margin:2px 0;
padding:5px 0;
}
.warning {
display: none;
border-bottom: 2px dotted red;
}
</style>
</head>
<body>
<div class="search">
<h3>Процен использования</h3>
<dl>
<dt><label for="check-0">Закладки</label></dt>
<dd><input type="number" name="check[0]" id="check-0" min="0" max="100" value="30" /></dd>
<dt><label for="check-1">Yandex.ru</label></dt>
<dd><input type="number" name="check[1]" id="check-1" min="0" max="100" value="40" /></dd>
<dt><label for="check-2">Google.ru</label></dt>
<dd><input type="number" name="check[2]" id="check-2" min="0" max="100" value="20" /></dd>
<dt><label for="check-3">Nigma.ru</label></dt>
<dd><input type="number" name="check[3]" id="check-3" min="0" max="100" value="10" /></dd>
<dt><label for="check-4">Qip.ru</label></dt>
<dd><input type="number" name="check[4]" id="check-4" min="0" max="100" value="0" /></dd>
<dt><label for="check-5">Go.mail.ru</label></dt>
<dd><input type="number" name="check[5]" id="check-5" min="0" max="100" value="0" /></dd>
<dt><label for="check-6">Rambler.ru</label></dt>
<dd><input type="number" name="check[2]" id="check-6" min="0" max="100" value="0" /></dd>
<dt><label for="check-7">Google.com.ua</label></dt>
<dd><input type="number" name="check[1]" id="check-7" min="0" max="100" value="0" /></dd>
<dt><label for="check-8">Meta.ua</label></dt>
<dd><input type="number" name="check[2]" id="check-8" min="0" max="100" value="0" /></dd>
<dt><label for="check-9">Yandex.ua</label></dt>
<dd><input type="number" name="check[2]" id="check-9" min="0" max="100" value="0" /></dd>
<dt><label for="check-10">Bigmir.net</label></dt>
<dd><input type="number" name="check[2]" id="check-10" min="0" max="100" value="0" /></dd>
<dt><label for="check-11">Bing.com</label></dt>
<dd><input type="number" name="check[2]" id="check-11" min="0" max="100" value="0" /></dd>
<dt><label for="check-12">Yandex.com</label></dt>
<dd><input type="number" name="check[2]" id="check-12" min="0" max="100" value="0" /></dd>
</dl>
<span class="warning">Сумма должна быть равной 100!</span>
</div>
<script src="https://code.jquery.com/jquery-2.1.4.js"></script>
<script>
$('.search').on('change', 'input', function() {
var inpElems = $('.search input'),
result = 0,
warning = $('.warning');
inpElems.each(function() {
result += +$(this).val();
});
if (result <= 100) {
inpElems.each(function() {
$(this).css('background', '');
warning.hide();
});
} else {
$(this).css('background', 'red');
warning.show();
}
!$(this).val() && $(this).val(0);
});
</script>
</body>
</html>