有效沟通问答-【官方】百战程序员_IT在线教育培训机构

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 盒子模型之组成部分：
                1.内容区域 Content
                   1) 默认大小：由内容本身大小撑开
                   2）手动设置：由width和height两个属性来完成盒子大小设置

                2.内边距  Padding
                3.外边框  Border
                4.外边距  Margin-->

        <!-- 实操细节：
                    1.宽度设置百分比生效
                    2.高度设置百分比不生效，高度一般设置px
                 -->
    <style>
        .image{
            width:30%;   /*手动设置了图片内容大小，不压缩比例，只设置高度即可*/
            /* 因为手机屏幕大小不是固定尺寸的，所以手机宽度一般设置百分比，这样可以适配各种尺寸的手机，
            为原比例的30% */
        }
    </style>
</head>
<body>
    <img class="image" src="hmbb.jpg" alt="海绵宝宝">
</body>
</html>

问题：为什么高度height设置百分比不生效呢？

搞不懂这个实操细节，意思是设置高度只能用XXpx，而宽度可以是XXpx和百分比吗？

那什么情况下，只设置width,不设置height？什么情况下只设置高度不设置宽度呢？

WEB前端全系列/第一阶段：HTML5+CSS3模块/CSS盒子模型 369楼

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>

        *{
            margin: 0;
            padding: 0;
        }

        body{
            background-color: #f1f1f1;
        }

        .container{
            width: 1240px;
            margin: 0 auto;
        }

        .container ul{
            overflow: hidden;
            clear: both;
        }

        .container ul li{
            position: relative;
            float: left;
            list-style: none;
            background-color: #fff;
            margin-top: 10px;
            margin-right: 9px;
            width: 303px;
            height: 375px;
        }

        .container ul li a img{
            height: 230px;
            margin-top: 30px;
        }

        .container ul li:nth-child(4n){
            margin-right: 0;
        }

        .container ul li a{
            display: block;
            width: 100%;
            height: 100%;
            text-align: center;
            text-decoration: none;
        }

        .text .name{
            display: block;
            color: #333;
            font-size: 16px;
            margin-bottom: 2px;
        }

        .text .desc{
            display: block;
            color: #999;
            font-size: 14px;
        }
 
        .text .price i{
            font-style: normal;
            font-size: 14px;
            bottom: 3px;
        }
 
        .text .price{
            display: inline-block;
            color: #c00;
            font-size: 22px;
            padding-left: 14px;
        }
 
        .text .price em{
            font-size: 16px;
            font-style: normal;
        }
 
        .product-sign{
            position:absolute;
            top: 30px;
            left: 30px;
            display: block;
            width: 60px;
            height: 60px;
            background-color: #ff64a6;
            border-radius: 50%;
            line-height: 60px;
            color: #fff;
            font-size: 16px;
            text-align: center;
        }
 
 
    </style>
</head>
<body>
   
    <div class="container">
        <ul>
            <li>
                <a href="#">
                    <img src="./1.png" alt="">
                    <div class="text">
                        <span class="name">魅族 18</span>
                        <span class="desc">限时领券最高立省1000 | 12期免息</span>
                        <span class="price"><i>￥</i>3900<em>起</em></span>
                    </div>
                    <span class="product-sign">免息</span>
                </a>
            </li>
            <li>
                <a href="#">
                    <img src="./1.png" alt="">
                    <div class="text">
                        <span class="name">魅族 18</span>
                        <span class="desc">限时领券最高立省1000 | 12期免息</span>
                        <span class="price"><i>￥</i>3900<em>起</em></span>
                    </div>
                    <span class="product-sign">免息</span>
                </a>
            </li>
            <li>
                <a href="#">
                    <img src="./1.png" alt="">
                    <div class="text">
                        <span class="name">魅族 18</span>
                        <span class="desc">限时领券最高立省1000 | 12期免息</span>
                        <span class="price"><i>￥</i>3900<em>起</em></span>
                    </div>
                    <span class="product-sign">免息</span>
                </a>
            </li>
            <li>
                <a href="#">
                    <img src="./1.png" alt="">
                    <div class="text">
                        <span class="name">魅族 18</span>
                        <span class="desc">限时领券最高立省1000 | 12期免息</span>
                        <span class="price"><i>￥</i>3900<em>起</em></span>
                    </div>
                    <span class="product-sign">免息</span>
                </a>
            </li>
        </ul>
    </div>
</body>
</html>

.container ul li{

position: relative;

}这里面的position一定要用relative相对定位吗？

WEB前端全系列/第一阶段：HTML5+CSS3模块/浮动与定位 370楼

有序列表可以这样嵌套吗：

<ol>
<li>肉类：
    <ol>
        <li>猪肉</li>
        <li>鸡肉</li>
        <li>牛肉</li>
    </ol>
</li>
<li>蔬菜</li>
<li>水果</li>
</ol>

WEB前端全系列/第一阶段：HTML5+CSS3模块/HTML5基础元素 371楼

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul {
            color: red;
        }
    </style>
</head>
<body>
    <ul>
        <li>你好</li>
        <li>
            <ul>
                <li>好的</li>
                <li>好的</li>
                <li>好的</li>
            </ul>
        </li>
        <li>你好</li>
    </ul>
</body>
</html>

这里改变样式直接用ul{}不就可以了，为什么要用ui li{}的后代选择器

WEB前端全系列/第一阶段：HTML5+CSS3模块/CSS选择器 372楼

你好老师，为啥我用新标签这个完全显示不了？没看出问题在哪儿
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .header{
            width: 1400px;
            background-color: pink;
        }
        div{
            margin-top: 10px;
            height: 600px;
        }
        .nav{
            height: 80px;
            margin-top: 10px;
            background-color: pink;
        }
        .section{
            width: 900px;
            margin-top: 10px;
            background-color: pink;
            height: 600px;
            float: left;
        }
        aside{
            width: 480px;
            margin-top: 10px;
            background: pink;
            height: 600px;
            float: right;
        }
        .footer{
            height: 80px;
            margin-top: 10px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <header>头部</header>
    <nav>导航</nav>
    <div>
        <section>主要内容</section>
        <aside>侧边栏</aside>
    </div>
    <footer>脚部</footer>
</body>
</html>

WEB前端全系列/第一阶段：HTML5+CSS3模块/HTML5新增元素 373楼

为什么我的main主要内容和侧边栏显示不出来，代码如下：
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container{
            width: 1400px;
            margin: 0 auto;
        }
        .header{
            height: 80px;
            margin-top: 10px;
            background:pink
        }
        .nav{
            height: 80px;
            margin-top: 10px;
            background: pink;
        }
        .main{
            height: 500px;
            margin-top: 10px;
        }  
        .mian .left{
            float: left;
            width: 900px;
            height: 500px;
            background: pink;
        }
        .mian .right{
            float: right;
            width: 480px;
            height: 500px;
            background: pink;
        }
        .footer{
            height: 80px;
            background: pink;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="header">头部</div>
        <div class="nav">导航</div>
        <div class="main">
            <div class="left">主要内容</div>
            <div class="right">侧边栏</div>
        </div>
        <div class="footer">脚部</div>
    </div>
</body>
</html>

WEB前端全系列/第一阶段：HTML5+CSS3模块/HTML5新增元素 374楼

<form action="" method="post">

            <input type="text" value=""/>

            <button type="reset">重置</button>

        </form>

那这个意思是不是说重置按钮只能重置同一个form表单下输入框的数据，那么本次实操中这个重置按钮的意义是什么？或者说用什么办法能实现整个表格的重置？

WEB前端全系列/第一阶段：HTML5+CSS3模块/表单 375楼

同学您好