初學者代碼：ID內的HTML樣式ID不起作用

我剛剛開始學習HTML，並且遇到ID /類中ID /類的問題。初學者代碼：ID內的HTML樣式ID不起作用

所以，就我所知，一個ID由＃指定。這將意味着，如果我想內ID樣式的ID，那不是：

#ID1 #ID2 { 
    ... 
}

這將意味着造型只適用於ID2是裏面ID1？如果我錯了，請糾正我。當我在我的（非常簡單的初學者）代碼中使用相同的原則時，它不起作用。這裏是我的代碼：

<!DOCTYPE html> 
<html> 

<head> 
    <title>1 May 2016</title> 
    <style> 
     #name { 
      color: blue; 
      font-family: Tahoma; 
     } 

     #parafont #1 { 
      font-family: Arial; 
     } 

     #parafont #2 { 
      font-family: Times; 
     } 

     #parafont #3 { 
      font-family: Courier; 
     } 

     parafont #4 { 
      font-family: Lucida Grande; 
     } 

     #parafont #5 { 
      font-family: Helvetica; 
     } 

     #test1 #6 { 
      color: blue; 
     } 
    </style> 
</head> 

<body> 
    <h3 id="name">Bob Bobbington</h3> 
    <p>1 2 3 4 5 6 7 8 9 10</p> 
    <p>When was this website created? Check the <b>title</b>.</p> 
    <h3>All animals are quite interesting...</h3> 
    <p id="parafont"> 
     <span id="1">This is a test paragraph.</span> 
     <span id="2">Each sentence should have a different font.</span> 
     <span id="3">This paragraph is going to use some styling.</span> 
     <span id="4">Styling will change the font of each sentence.</span> 
     <span id="5">Let's see whether it works!</span> 
    </p> 
    <div id="test1"> 
     <p id="6">Test</p> 
    </div> 
</body> 

</html>

所有幫助非常感謝！

來源

2016-05-01 WeavingBird1917