CSS3 Trang 404 hiệu ứng đẹp

Demo

Đầu tiên các bạn chèn CSS cho trang 404:

body {
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  margin: 0;
  padding: 0;
  background-color: #446072;
  font-family: "Microsoft YaHei",sans-serif;
  color: white;
  -webkit-box-pack: center;
  -webkit-justify-content: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
  -webkit-align-items: center;
      -ms-flex-align: center;
          align-items: center;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -webkit-flex-direction: column;
      -ms-flex-direction: column;
          flex-direction: column;
  overflow: hidden;
}
h1 {
  margin-top: 2rem;
}
p{
  font-family: "Microsoft YaHei","Segoe UI", "Lucida Grande", Helvetica, Arial,sans-serif;
}
.shelf {
  position: relative;
  width: 30rem;
  height: 14rem;
  border: 0.5rem solid #374d5b;
  border-radius: 0.5rem;
  background-color: rgba(255, 255, 255, 0.1);
  -webkit-perspective: 130rem;
          perspective: 130rem;
  box-shadow: inset 0 0 2rem rgba(0, 0, 0, 0.2);
}
.door {
  position: absolute;
  width: 14.8rem;
  height: 14rem;
  display: -webkit-box;
  display: -webkit-flex;
  display: -ms-flexbox;
  display: flex;
  box-sizing: border-box;
  padding: 1rem;
  background-color: #374d5b;
  -webkit-box-align: center;
  -webkit-align-items: center;
      -ms-flex-align: center;
          align-items: center;
  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.3);
}
.door::before {
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 50%;
  background-color: rgba(0, 0, 0, 0.1);
  content: "";
}
.door.left {
  border-radius: 0 0.75rem 0.75rem 0;
  -webkit-box-pack: end;
  -webkit-justify-content: flex-end;
      -ms-flex-pack: end;
          justify-content: flex-end;
  -webkit-animation: 
      leftDoorOpen 3.5s ease-out forwards 1s,
      leftDoorFlap 15s linear infinite forwards 9s;
          animation: 
      leftDoorOpen 3.5s ease-out forwards 1s,
      leftDoorFlap 15s linear infinite forwards 9s;
  -webkit-transform-origin: 0 0 0;
          transform-origin: 0 0 0;
}
.door.right {
  right: 0;
  border-radius: 0.75rem 0 0 0.75rem;
  -webkit-animation: 
      rightDoorOpen 3s ease-out forwards 1.5s,
      rightDoorFlap 10s linear infinite forwards 8s;
          animation: 
      rightDoorOpen 3s ease-out forwards 1.5s,
      rightDoorFlap 10s linear infinite forwards 8s;
  -webkit-transform-origin: 100% 0 0;
          transform-origin: 100% 0 0;
}
.book {
  position: absolute;
  box-sizing: border-box;
  padding: 0.8rem 4rem 0.8rem 2rem;
  border-radius: 0.25rem;
  background-color: rgba(255, 255, 255, 0.1);
  color: white;
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.1rem;
  cursor: pointer;
  box-shadow: inset 0 0 0.75rem rgba(255, 255, 255, 0.1);
}
.book.home-page {
  -webkit-transform: rotate(-90deg) translate(-12.4rem, 3rem);
          transform: rotate(-90deg) translate(-12.4rem, 3rem);
  -webkit-transform-origin: 0;
          transform-origin: 0;
}
.book.about-us {
  -webkit-transform: rotate(-100deg) translate(-13.4rem, 6.1rem);
          transform: rotate(-100deg) translate(-13.4rem, 6.1rem);
  -webkit-transform-origin: 0;
          transform-origin: 0;
}
.book.contact {
  right: 2rem;
  bottom: 0.2rem;
  border-radius: 0.3rem 0 0 0.3rem;
}
.book.faq {
  right: 0.8rem;
  bottom: 3.3rem;
  border-radius: 0.3rem 0 0 0.3rem;
}
.book.not-found {
  width: 12rem;
  height: 3.5rem;
  border: 1px dashed rgba(255, 255, 255, 0.3);
  background-color: transparent;
  -webkit-transform: rotate(-90deg) translate(-12rem, 13rem) scale(1);
          transform: rotate(-90deg) translate(-12rem, 13rem) scale(1);
  -webkit-transform-origin: 0;
          transform-origin: 0;
  cursor: default;
  -webkit-animation: bookFadeOut 1s 3s infinite forwards;
          animation: bookFadeOut 1s 3s infinite forwards;
}
.book.not-found::after {
  display: block;
  width: 10rem;
  padding-left: 5rem;
  background-image: url("data:image/svg+xml;utf8,");
  background-repeat: no-repeat;
  background-size: 4rem;
  background-position: left center;
  font-family: "Dancing Script";
  text-transform: lowercase;
  font-size: 25px;
  content: "this page can't be found";
  -webkit-transform: rotate(90deg) translate(6rem, -1rem);
          transform: rotate(90deg) translate(6rem, -1rem);
  opacity: 0.3;
}
.book:hover:not(.not-found) {
  background-color: rgba(255, 255, 255, 0.2);
}
@-webkit-keyframes leftDoorOpen {
  60% {-webkit-transform: rotateY(-115deg);transform: rotateY(-115deg)}
  100% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
}
@keyframes leftDoorOpen {
  60% {-webkit-transform: rotateY(-115deg);transform: rotateY(-115deg)}
  100% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
}
@-webkit-keyframes rightDoorOpen {
  60% {-webkit-transform: rotateY(125deg);transform: rotateY(125deg)}
  100% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
}
@keyframes rightDoorOpen {
  60% {-webkit-transform: rotateY(125deg);transform: rotateY(125deg)}
  100% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
}
@-webkit-keyframes rightDoorFlap {
  0% { -webkit-transform: rotateY(120deg); transform: rotateY(120deg)}
  5% {-webkit-transform: rotateY(125deg);transform: rotateY(125deg)}
  15% {-webkit-transform: rotateY(117deg);transform: rotateY(117deg)}
  25% {-webkit-transform: rotateY(123deg);transform: rotateY(123deg)}
  30% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
  100% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
}
@keyframes rightDoorFlap {
  0% { -webkit-transform: rotateY(120deg); transform: rotateY(120deg)}
  5% {-webkit-transform: rotateY(125deg);transform: rotateY(125deg)}
  15% {-webkit-transform: rotateY(117deg);transform: rotateY(117deg)}
  25% {-webkit-transform: rotateY(123deg);transform: rotateY(123deg)}
  30% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
  100% {-webkit-transform: rotateY(120deg);transform: rotateY(120deg)}
}
@-webkit-keyframes leftDoorFlap {
  0% { -webkit-transform: rotateY(-110deg); transform: rotateY(-110deg)}
  5% {-webkit-transform: rotateY(-115deg);transform: rotateY(-115deg)}
  15% {-webkit-transform: rotateY(-107deg);transform: rotateY(-107deg)}
  25% {-webkit-transform: rotateY(-113deg);transform: rotateY(-113deg)}
  30% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
  100% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
}
@keyframes leftDoorFlap {
  0% { -webkit-transform: rotateY(-110deg); transform: rotateY(-110deg)}
  5% {-webkit-transform: rotateY(-115deg);transform: rotateY(-115deg)}
  15% {-webkit-transform: rotateY(-107deg);transform: rotateY(-107deg)}
  25% {-webkit-transform: rotateY(-113deg);transform: rotateY(-113deg)}
  30% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
  100% {-webkit-transform: rotateY(-110deg);transform: rotateY(-110deg)}
}
@-webkit-keyframes bookFadeOut {
  50% {border: 1px dashed rgba(255, 255, 255, 0.1);}
}
@keyframes bookFadeOut {
  50% {border: 1px dashed rgba(255, 255, 255, 0.1);}
}

Tiếp đó là đoạn code hiện thị trang 404 nữa là xong:

 <nav class="shelf">
   <a class="book home-page">Home page</a>
   <a class="book about-us">About us</a>
   <a class="book contact">Contact</a>
   <a class="book faq">F.A.Q.</a>
  
   <span class="book not-found"></span>
 
   <span class="door left"></span>
   <span class="door right"></span>
 </nav>
 <h1>Error 404</h1>