CSS类无效

Question

TL; DR

这是我的CSS代码和HTML代码

<div class="navbar">
            <nav>
                    <span id="logo">
                        <a href="index.html">Logo</a>
                    </span>
                    <ul class="menu">
                        <li><a href="#home">Home</a></li>
                        <li><a href="#about">About Me</a></li>
                        <li><a href="#contact">Contact</a></li>
                    </ul>
                    <div id="toggle">
                        <div class="span" id="one"></div>
                        <div class="span" id="two"></div>
                        <div class="span" id="three"></div>
                    </div>                        
                </nav>
    </div>

CSS：

 * {
    margin: 0;
    padding: 0;
    text-decoration: none;
    list-style: none;
}

结果：https://imgur.com/a/c6rWS3V（第二张图片）

如果我将*替换为.navbar类，则会得到以下结果（图像2，谢谢！） https://imgur.com/a/c6rWS3V（第一张图片）

以下较长版本：（如果将*交换为.navbar，它将无法正常工作）问题是为什么？

* {
    margin: 0;
    padding: 0;
    text-decoration: none;
    list-style: none;
}

nav {
    width: 100%;
    background: #000;
    height: 70px;
    position: static;
    z-index: 1;
}

nav #logo {
    float: left;
    display: block;
    margin-left: 84px;
    font-size: 30px;
    line-height: 70px;
    font-weight: bold;
}

nav #logo a {
    color: #fff;
    transition: all 0.3s ease-out;
    font-family: 'Poppins', sans-serif;
    font-weight: 300;
}

nav .menu {
    float: left;
    left: 50%;
    position: relative;
}

nav .menu li {
    display: inline-block;
    padding: 0px 30px;
    cursor: pointer;
    line-height: 70px;
    position: relative;
    transition: all 0.3s ease-out;
}

nav .menu li a {
    color: #fff;
    font-family: 'Poppins', sans-serif;
    font-weight: 200;
}

#toggle {
    position: absolute;
    right: 20px;
    top: 14px;
    z-index: 999;
    width: 40px;
    height: 40px;
    cursor: pointer;
    float: right;
    transition: all 0.3s ease-out;
    visibility: hidden;
    opacity: 0;
}

#toggle .span {
    height: 3px;
    background: #fff;
    transition: all 0.3s ease-out;
    backface-visibility: hidden;
    margin: 5px auto;
}

#toggle.on #one {
    transform: rotate(45deg) translateX(2px) translateY(4px);
}

#toggle.on #two {
    opacity: 0;
}

#toggle.on #three {
    transform: rotate(-45deg) translateX(8px) translateY(-10px);
}


@media(max-width: 768px) {
    #toggle {
        visibility: visible;
        opacity: 1;
        margin-top: 6px;
    }
    nav #logo {
        margin-left: 18px;
    }
    .menu a {
        font-family: 'Poppins', sans-serif;
        font-weight: 200;
        font-size: 20px;
    }
    nav .menu {
        display: none;
    }
}
@media only screen and (max-width: 1366px) and (min-width: 1024px)
{
    .menu a {
        position: relative;
        margin-left: -30px;
        font-size: 2vw;
    }
}
@media only screen and (width: 812px) and (min-width: 375px)/* IPHONE X */
{
    .menu a {
        position: relative;
        margin-left: -80px;
        font-size: 2vw;
    }
}
@media only screen and (width: 823px) and (min-width: 411px) /*GOOGLE PIXEL 2XL */
{
    .menu a {
        position: relative;
        margin-left: -120px;
        font-size: 2vw;
    }
}

 <div class="navbar">
                <nav>
                        <span id="logo">
                            <a href="index.html">Logo</a>
                        </span>
                        <ul class="menu">
                            <li><a href="#home">Home</a></li>
                            <li><a href="#about">About Me</a></li>
                            <li><a href="#contact">Contact</a></li>
                        </ul>
                        <div id="toggle">
                            <div class="span" id="one"></div>
                            <div class="span" id="two"></div>
                            <div class="span" id="three"></div>
                        </div>                        
                    </nav>
        </div>

谢谢！ 附：我尽力使用这个编辑器，但还是新的！尽管我认为我做的很好：D

Answer 1

始终将text-decoration:none添加到a标签

.navbar #logo a{
  text-decoration:none;
}

---

*{
css rules
}

适用于所有内容（包括a标记），这就是为什么您不会对徽标加下划线。

* {
    margin: 0;
    padding: 0;
   /* text-decoration: none;*/ /* Comeented for sake of answer*/
    list-style: none;
}

nav {
    width: 100%;
    background: #000;
    height: 70px;
    position: static;
    z-index: 1;
}

nav #logo {
    float: left;
    display: block;
    margin-left: 84px;
    font-size: 30px;
    line-height: 70px;
    font-weight: bold;
}

nav #logo a {
    color: #fff;
    transition: all 0.3s ease-out;
    font-family: 'Poppins', sans-serif;
    font-weight: 300;
}

nav .menu {
    float: left;
    left: 50%;
    position: relative;
}

nav .menu li {
    display: inline-block;
    padding: 0px 30px;
    cursor: pointer;
    line-height: 70px;
    position: relative;
    transition: all 0.3s ease-out;
}

nav .menu li a {
    color: #fff;
    font-family: 'Poppins', sans-serif;
    font-weight: 200;
}

#toggle {
    position: absolute;
    right: 20px;
    top: 14px;
    z-index: 999;
    width: 40px;
    height: 40px;
    cursor: pointer;
    float: right;
    transition: all 0.3s ease-out;
    visibility: hidden;
    opacity: 0;
}

#toggle .span {
    height: 3px;
    background: #fff;
    transition: all 0.3s ease-out;
    backface-visibility: hidden;
    margin: 5px auto;
}

#toggle.on #one {
    transform: rotate(45deg) translateX(2px) translateY(4px);
}

#toggle.on #two {
    opacity: 0;
}

#toggle.on #three {
    transform: rotate(-45deg) translateX(8px) translateY(-10px);
}


@media(max-width: 768px) {
    #toggle {
        visibility: visible;
        opacity: 1;
        margin-top: 6px;
    }
    nav #logo {
        margin-left: 18px;
    }
    .menu a {
        font-family: 'Poppins', sans-serif;
        font-weight: 200;
        font-size: 20px;
    }
    nav .menu {
        display: none;
    }
}
@media only screen and (max-width: 1366px) and (min-width: 1024px)
{
    .menu a {
        position: relative;
        margin-left: -30px;
        font-size: 2vw;
    }
}
@media only screen and (width: 812px) and (min-width: 375px)/* IPHONE X */
{
    .menu a {
        position: relative;
        margin-left: -80px;
        font-size: 2vw;
    }
}
@media only screen and (width: 823px) and (min-width: 411px) /*GOOGLE PIXEL 2XL */
{
    .menu a {
        position: relative;
        margin-left: -120px;
        font-size: 2vw;
    }
}

.navbar #logo a{
text-decoration:none;
}

<div class="navbar">
                <nav>
                        <span id="logo">
                            <a href="index.html">Logo</a>
                        </span>
                        <ul class="menu">
                            <li><a href="#home">Home</a></li>
                            <li><a href="#about">About Me</a></li>
                            <li><a href="#contact">Contact</a></li>
                        </ul>
                        <div id="toggle">
                            <div class="span" id="one"></div>
                            <div class="span" id="two"></div>
                            <div class="span" id="three"></div>
                        </div>                        
                    </nav>
        </div>