title: What is wrong with my javascript onclick and onmouseover?
body: <p>I want to make a simple quiz. I have this code, but the Javascript part doesn't work. CSS is okay, but when it comes to <code>onclick</code> and <code>onmouseover</code> nothing happens. Here is my code:</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  
  &lt;style&gt;
      body {
          background: url(bild.jpg);
          background-size: 100% 100%;
          background-repeat: no-repeat;
      }
      .a {
          position: absolute;
          top: 50%;
          left: 50%;
          margin-top: -130px;
          margin-left: -500px;
          width: 400px;
          height: 50px;
          font-size: 30;
          color: black;
      }
      .b {
          position: absolute;
          top: 50%;
          left: 50%;
          margin-top: -130px;
          margin-left: -20px;
          width: 400px;
          height: 50px;
          font-size: 30;
          color: black;
      }
      .c {
          position: absolute;
          top: 50%;
          left: 50%;
          margin-top: -30px;
          margin-left: -500px;
          width: 400px;
          height: 50px;
          font-size: 30;
          color: black;
      }
      .d {
          position: absolute;
          top: 50%;
          left: 50%;
          margin-top: -30px;
          margin-left: -20px;
          width: 400px;
          height: 50px;
          font-size: 30;
          color: black;
      }
  &lt;/style&gt;
  &lt;title&gt;Moseso.de Quiz&lt;/title&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  
  &lt;script&gt;
      function overa() {
          document.getElementById("a").style.background="green";
      }
      function overb() {
          document.getElementById("b").style.background="green";
      }
      function overc() {
          document.getElementById("c").style.background="green";
      }
      function overd() {
          document.getElementById("d").style.background="green";
      }
      function outa() {
          document.getElementById("a").style.background="white";
      }
      function outb() {
          document.getElementById("b").style.background="white";
      }
      function outc() {
          document.getElementById("c").style.background="white";
      }
      function outd() {
          document.getElementById("d").style.background="white";
      }
      function true() {
          alert("Richtig!");
      }
      function false() {
          alert("Falsch");
      }
  &lt;/script&gt;
  
  &lt;button class="a" id="a" onmouseover="overa();" onmouseout="outa();" onclick"true();"&gt;Antwort A&lt;/&gt;
  &lt;button class="b" id="b" onmouseover="overb();" onmouseout="outb();" onclick"false();"&gt;Antwort B&lt;/&gt;
  &lt;button class="c" id="c" onmouseover="overc();" onmouseout="outc();" onclick"false();"&gt;Antwort C&lt;/&gt;
  &lt;button class="d" id="d" onmouseover="overd();" onmouseout="outd();" onclick"false();"&gt;Antwort D&lt;/&gt;
  
  &lt;script&gt;
      window.onload = function() {
          document.getElementById("a").style.background="#E6E6E6";
          document.getElementById("b").style.background="#E6E6E6";
          document.getElementById("c").style.background="#E6E6E6";
          document.getElementById("d").style.background="#E6E6E6";
      }
  &lt;/script&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>It would be very nice if someone could answer my question because I tried many times. The script is German BTW :)</p>