snow

information & source

spanにクラス指定で背景色をつけています。

span無しだとこんな感じになります。

スマートフォンサンプル

CSS

@charset "UTF-8";

*{margin: 0; padding: 0;}

body{
	color: #000;
	font-size: 13px;
	background-color: #e0e0e0;
	letter-spacing: 0.2em;
    line-height: 2;
}

a {
	padding: 0.1em 0.3em;
	position: relative;
	display: inline-block;
	transition: .3s;
	color: #be0502;
    text-decoration: none;
}

a:hover {
	color:#000;
}

#wrapper{
	position: relative;
	display: flex;
	flex-wrap: wrap;
}

/*左エリア*/
#fixed-area {
    position: -webkit-sticky; 
    position: sticky;
    top: 0;
    width: 30%;
    height: 100vh;
    display: flex;
    flex-direction: column; 
    justify-content: center; 
    align-items: center;
}

#fixed-area a{
    position: relative;
    text-decoration: none;
    color: #000;
    background-color: #fff;
    text-decoration:none;
    display: inline-block;
    padding: 1em 0.3em;
    margin: 20px 0;
    transition: all .3s;
}

#fixed-area a:visited{
    color: #000;
}

#fixed-area a:hover{
    color: #202020;
    background-color: #be0502;
}

h1{
	writing-mode: vertical-rl;
	margin: 0 auto;

}

.nav{
	writing-mode: vertical-rl;
}

h1{
	margin: 50px 0;
}

/*右エリア*/
#container{
	width:70%;
}

.box{
	width: 70%;
	margin: 100px 0 100px 0;
}

p{
    margin: 10px 0;
}

.highlight {
    background-color: #fff;
    padding: 0.3em 0;
}

.heading {
	display: flex;
	align-items: center;
  }
  
.bar {
    width: 75px;
    height: 1px;
    background-color: #000;
}

h2 {
    font-size: 18px;
    font-weight: bold;
    background-color: #fff;
    padding: 0 0.5em;
    margin: 0 0 10px 0;
}

/* 装飾 */

.log{
    font-size: 12px;
}

hr {
    height: 0;
    margin: 25px auto 25px auto;
    padding: 0;
    border: 0;
    width: 200px;
    border-top: 1px solid #000;
}

input{
    background-color: #fff;
    color: #000;
    font-size: 12px;
    border: solid 1px #000;
}

@media screen and (max-width:768px){

#wrapper{
	display: block;
}

#fixed-area{
 	position:relative!important;
	width:100%;
	height: 35vh;
}

#container{
	width:100%;
}

h1{
	writing-mode: horizontal-tb; 
	text-align: center;
	margin: 0 auto;
}

.nav {
	writing-mode: horizontal-tb;
	text-align: center;
}

.box{
	width: 85%;
	margin: 100px auto;
}

.log{
    text-align: center;
  }

}

HTML

<!DOCTYPE html>
<html lang="ja">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>site</title>
    <link rel="stylesheet" href="CSSファイル">
</head>
<body>

<div id="container">

<div class="heading">
                <div class="bar"></div>
                <h2>title</h2>
                </div>

</div>
        </div>
    </div>
    
</body>
</html>

snow

sample

information & source