scoll up and down text in html legend Phonegap

I want to scoll up and down text in tag legend if text is longer than height

this is my code

<fieldset >

        <legend id = "show_question" style="height: 150px;" class="slidedown">1)1+1 = ?</legend>

        <input type="radio" name="num1" id="aa" value = "a" onclick = "answer_click('a')" />
        <label id = "show_ch1" for="aa">A.</label>

        <input type="radio" name="num1" id="bb" value = "b" onclick = "answer_click('b')"  />
        <label id = "show_ch2" for="bb">B.</label>

        <input type="radio" name="num1" id="cc" value = "c" onclick = "answer_click('c')"  />
        <label id = "show_ch3" for="cc">C.</label>

        <input type="radio" name="num1" id="dd" value = "d" onclick = "answer_click('d')"  />
        <label id = "show_ch4" for="dd">D.</label>

    </fieldset>