<button class="button">
    <span class="button__text button__text--on">ON</span>
    <span class="button__text button__text--off">OFF</span>
</button>

<div class="site-wrapper">
    <!-- Шапка сайта -->
    <header class="site-header">
      <h1 class="site-header__title">Название сайта</h1>

      <nav class="site-header__nav site-nav">
        <a href="#" class="site-nav__link">О продукте</a>
        <a href="#" class="site-nav__link">О погоде</a>
        <a href="#" class="site-nav__link">О чём шумит камыш</a>
      </nav>
    </header>

    <!-- Главное содержимое страницы -->
    <main class="site-main">
      <!-- Разделы главного содержимого -->
      <section class="features">
        <h2 class="features__title">Преимущества</h2>

        <ul class="features__list">
          <li class="features__item">Высокие потолки</li>
          <li class="features__item">[...]</li>     
        </ul>
      </section>

      <section class="prices">
        <h2 class="prices__title">Тарифы</h2>

        <ul class="prices__list">
          <li class="prices__item">30 зонтиков в минуту</li>
          <li class="prices__item">[...]</li>     
        </ul>
      </section>
    </main>

    <!-- Боковая колонка -->
    <aside class="site-aside">
      <div class="widget">
        <h3 class="widget__title">Как мы отдыхаем?</h3>
        <div class="widget__text">Читайте в нашей новой книге «Никак»</div>
      </div>
    </aside>

    <!-- Подвал сайта -->
    <footer class="site-footer">
      <ul class="site-footer__socials socials">
        <li class="socials__item">
          <a href="#" class="socials__link">Switter</a>
        </li>    
        <li class="socials__item">
          <a href="#" class="socials__link">Facebook</a>
        </li>    
        <li class="socials__item">   
          <a href="#" class="socials__link">Одноглазники</a>
        </li>
      </ul>

      <div class="site-footer__copyright copyright ">
        Сделано <a href="#" class="copyright__link">левой&nbsp;пяткой</a>
      </div>
    </footer>
</div>
BODY.outlines-on > * {
    outline: 2px solid deeppink;
}
BODY.outlines-on > * > * {
    outline: 2px dashed lime;
    outline-offset: -2px;
}
BODY.outlines-on > * > * > * {
    outline: 2px dotted dodgerblue;
    outline-offset: -4px;
}

/* Button
 -------------------- */

.button {
    position: absolute;
    top: 0;
    right: 2rem;
    min-width: 110px;
    outline: 0;
    padding: .75rem 1rem;
    box-sizing: border-box;
    background: #BBB;
    background-image: linear-gradient(
        hsla(0,0%,60%,.5) 1px, 
        hsla(0,0%,60%,0) 1px);
    background-size: .3rem .3rem;
    border: 0;
    box-shadow: 0 0 0 3px #AAA,
        0 3px 12px #000;
    border-radius: 0 0 5px 5px;
    outline: 0 !important;
    cursor: pointer;
    font-size: 18px;
    text-shadow: 1px 0 2px hsl(0,0%,87%),
        -1px 0 2px hsl(0,0%,87%),
        0 -1px 2px hsl(0,0%,87%),
        0 1px 2px hsl(0,0%,87%);
    text-align: left;
    
    &:before {
        content: '';
        display: inline-block;
        width: 1.5rem;
        height: 1.5rem;
        margin-right: .2rem;
        border-radius: 5px;
        box-shadow: 0 0 0 3px #999,
            0 -2px 7px hsla(0,0%,10%, 1) inset;
        background: #555;
        vertical-align: middle;
    }
    
    &__text {
        vertical-align: bottom;
        outline: 0 !important;
        font-weight: bold;
    }
}

.button__text--off {
    color: #444;
}
.button__text--on {
    display: none;
    color: #777;
    text-shadow: 1px 1px 2px white,
        -1px 1px 2px white;
}

.state-on {
   background-color: #DDD;
   background-image: linear-gradient(
        hsla(0,0%,70%,.5) 1px, 
        hsla(0,0%,70%,0) 1px); 
    
   box-shadow: 0 0 0 3px #CCC,
       0 3px 12px #000;
    
   &:before {
        box-shadow: 
            0 0 15px 3px greenyellow,
            0 0 0 3px #BBB,
            0 0 1px 2px hsla(150,0%,97%, 1),
            0 -2px 7px hsla(200,90%,90%, 1) inset,
            0 2px 7px hsla(80,50%,40%, 1) inset;
        background: greenyellow;
    } 
    
    .button__text--on {
        display: inline-block;
    }
    .button__text--off {
        display: none;
    }
}

/* Layout 
 ------------------------------ */

HTML {
    height: 100%;
}
BODY {
    display: flex;
    justify-content: space-around;
    align-items: center;
    min-height: 100%;
    font: 12px/1.4 Arial, sans-serif;
}

A {
    color: steelblue;
}

H1 {
    font-size: 3rem;
}
H2 {
    margin-bottom: .5em;
    font-size: 2rem;
}
H3 {
    margin-bottom: .5em;
    font-size: 1.3rem;
}

LI:before {
    content: '— ';
}

.site-wrapper {
    width: 75vw;
    min-width: 320px;
    display: flex;
    flex-wrap: wrap;
    padding: .5rem;
}

/* Header
 -------------------- */

.site-header {
    width: 100%;
    margin-bottom: 1rem;
    padding: .5rem 1.5rem;
}

.site-header__title {
    margin-bottom: 1rem;
    padding: .5rem 1rem;
}

.site-header__nav {
    display: flex;
    justify-content: space-between;
    padding: .5rem 1rem;;
}

/* Main
 -------------------- */

.site-main {
    flex-grow: 1;
    padding: 1rem 1.5rem;
}

.features,
.prices {
    padding: .5rem 1rem;
}

/* Aside
 -------------------- */

.site-aside {
    display: none;
    width: 25vw;
    margin-left: .5rem;
    padding: 1rem;
    
    @media ( min-width: 600px ) {
        display: block;
    }
}

.widget {
    padding: .5rem;
}

/* Footer
 -------------------- */

.site-footer {
    width: 100%;
    margin-top: 1rem;
    padding: .5rem 1.5rem;
    
    display: flex;
    justify-content: space-between;
}

.socials {
    width: 50%;
    padding: .5rem 1rem;
    
    @media ( min-width: 600px ) {
        display: flex;
        justify-content: space-between;
    }
}

.socials__item:before {
    content: none;
}

.copyright {
    padding: .5rem 1rem;
}
View Compiled
var button = document.querySelector('.button');

setClasses();

button.onclick = function () {
    setClasses();
}

function setClasses() {
    document.body.classList.toggle('outlines-on');
    button.classList.toggle('state-on');
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.