SOURCE

<header>
  <h1>Simple device mockups in CSS</h1>
  <p>Simple, responsive, single-div device mockups using raw CSS. Inspired by <a href='https://stripe.com/' target='_blank'>Stripe</a>. The devices automatically size to the dimensions of the image inside them.</p>
</header>

<div class='device-collection'>
  <div class='phone-container'>
    <div class='device phone'>
      <img src='https://trevoreyre.com/img/gbo-phone.jpg'>
    </div>
  </div>
  <div class='tablet-container'>
    <div class='device tablet'>
      <img src='https://trevoreyre.com/img/gbo-tablet.jpg'>
    </div>
  </div>
  <div class='device desktop'>
    <img src='https://trevoreyre.com/img/gbo-desktop.jpg'>
  </div>
</div>

<div class='container'>
  <div class='device phone'>
    <img src='https://placehold.it/187x333'>
  </div>
</div>
<div class='container'>
  <div class='device phone landscape'>
    <img src='https://placehold.it/333x187'>
  </div>
</div>
<div class='container'>
  <div class='device tablet'>
    <img src='https://placehold.it/384x512'>
  </div>
</div>
<div class='container'>
  <div class='device tablet landscape'>
    <img src='https://placehold.it/512x384'>
  </div>
</div>
<div class='container'>
  <div class='device laptop'>
    <img src='https://placehold.it/640x360'>
  </div>
</div>
<div class='container'>
  <div class='device desktop'>
    <img src='https://placehold.it/960x540'>
  </div>
</div>

.device {
  border-radius: 20px;
  position: relative;
  box-sizing: border-box;
  background: #fff;
  box-shadow: inset 0 4px 7px 1px #fff,
    inset 0 -5px 20px rgba(173, 186, 204, .25),
    0 2px 6px rgba(0, 21, 64, .14),
    0 10px 20px rgba(0, 21, 64, .05);
}

.device img {
  width: 100%;
  border-radius: 4px;
  border: 1px solid rgba(0, 0, 0, .24);
}

.device::before,
.device::after {
  content: "";
  display: block;
  position: absolute;
  background: #fff;
  box-shadow: inset 0 4px 7px 1px #fff,
    inset 0 -5px 20px rgba(173, 186, 204, .25),
    0 2px 6px rgba(0, 21, 64, .14),
    0 10px 20px rgba(0, 21, 64, .05);
}

.phone {
  padding: 12% 3%;
}

.phone.landscape {
  padding: 1.75% 8%;
}

.tablet {
  padding: 8% 2%;
}

.tablet.landscape {
  padding: 1.12% 6%;
}

.laptop {
  margin-left: 12%;
  margin-right: 12%;
  margin-bottom: 2.5%;
  border-radius: 1vw;
  padding: 1.35%;
}

.desktop {
  margin-bottom: 11%;
  border-radius: 1vw;
  padding: 1.5%;
}

// Phone button
.phone::after {
  border-radius: 50%;
  margin: 0 auto 2%;
  left: 0;
  right: 0;
  bottom: 0;
  width: 10%;
  height: 0;
  padding-top: 10%;
  box-shadow: inset 0 0 5px 1px rgba(0, 0, 0, .12);
}

.phone.landscape::after {
  margin: auto 0;
  left: calc(100% - 7%);
  top: 0;
  bottom: 0;
  width: 6%;
  padding-top: 6%;
}

// Phone speaker
.phone::before {
  border-radius: 50px;
  margin: 5.5% auto 0;
  left: 0;
  right: 0;
  top: 0;
  width: 20%;
  height: 1%;
  box-shadow: inset 0 0 3px 1px rgba(0, 0, 0, .12);
}

.phone.landscape::before {
  margin: auto 0 auto 4.5%;
  left: 0;
  top: 0;
  bottom: 0;
  width: 1%;
  height: 20%;
}

// Tablet button
.tablet::after {
  border-radius: 50%;
  margin: 0 auto 2%;
  left: 0;
  right: 0;
  bottom: 0;
  width: 6%;
  height: 0;
  padding-top: 6%;
  box-shadow: inset 0 0 5px 1px rgba(0, 0, 0, .12);
}

.tablet.landscape::after {
  margin: auto 0;
  left: calc(100% - 5.25%);
  top: 0;
  bottom: 0;
  width: 4.5%;
  padding-top: 4.5%;
}

// Tablet camera
.tablet::before {
  border-radius: 50%;
  margin: 3.5% auto 0;
  left: 0;
  right: 0;
  top: 0;
  width: 2.25%;
  height: 0;
  padding-top: 2.25%;
  background: #eee;
  box-shadow: inset 0 0 3px 1px rgba(0, 0, 0, .12);
}

.tablet.landscape::before {
  margin: auto 0 auto 2.5%;
  left: 0;
  top: 0;
  bottom: 0;
  width: 1.75%;
  padding-top: 1.75%
}

// Bottom of laptop
.laptop::after {
  border-radius: 4px 4px 48px 48px;
  left: -15%;
  bottom: -4%;
  width: 130%;
  height: 7%;
}

// Desktop arm
.desktop::before {
  margin: 0 auto;
  left: 0;
  right: 0;
  bottom: -18%;
  width: 20%;
  height: 20%;
  background: #fafafa;
  z-index: -1;
}

// Bottom of desktop stand
.desktop::after {
  border-radius: 4px 4px 24px 24px;
  margin: 0 auto;
  left: 0;
  right: 0;
  bottom: -19.5%;
  width: 34%;
  height: 2%;
}

// Phone, tablet, and desktop together
.device-collection {
  width: 100%;
  position: relative;
}

.device-collection::after {
  content: "";
  display: block;
  padding-top: 62.75%;
}

.device-collection .phone-container,
.device-collection .tablet-container,
.device-collection .desktop {
  position: absolute;
  bottom: 0;
}

.device-collection .phone,
.device-collection .tablet {
  margin: 0;
}

.device-collection .phone-container {
  left: 0;
  max-width: 15%;
  z-index: 2;
}

.device-collection .tablet-container {
  right: 0;
  max-width: 30%;
  z-index: 1;
}

.device-collection .desktop {
  left: 0;
  right: 0;
  margin: 0 5% 10.25%;
}

// May need to adjust this media query to get border-radius
// right on smaller screens. Unfortunately, border-radius as
// a percentage of parent container width doesn't work here.
@media (max-width: 800px) {
  .device-collection .device {
    border-radius: 1vw;
  }
}


// Page layout
body {
  margin: 0;
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
  align-items: center;
}

.container,
.device-collection {
  max-width: 100%;
  margin: 40px;
}

/* General layout and typography stuff */
@import url("https://fonts.googleapis.com/css?family=Open+Sans:300,400");

* {
  box-sizing: border-box;
  position: relative;
  transition: all .3s ease
}

html {
  font-size: 16px
}

body {
  font-family: Open Sans, Verdana, sans-serif;
  color: rgba(0, 0, 0, .87);
  font-weight: 400;
  line-height: 1.45
}

body,
header {
  background: #fafafa
}

header {
  padding: 40px;
  min-height: 200px;
  text-align: center;
  color: rgba(0, 0, 0, .87)
}

header > * {
  max-width: 800px;
  margin-left: auto;
  margin-right: auto
}

header>:last-child {
  margin-bottom: 0
}

h1 {
  margin-bottom: 0.5em;
  font-weight: inherit;
  line-height: 1.2;
  color: #1c5b72;
  font-size: 2.618em
}

@media (min-width:800px) {
  h1 {
    font-size: 4.236em;
    font-weight: 300
  }
}

p {
  margin-bottom: 1.3em;
  line-height: 1.618
}

@media (min-width:800px) {
  p {
    font-size: 1.3em
  }
}

a {
  color: #e03616;
  text-decoration: none
}