main.css

/* http://meyerweb.com/eric/tools/css/reset/
   v2.0 | 20110126
   License: none (public domain)
*/

html,
body,
div,
span,
applet,
object,
iframe,
h1,
h2,
h3,
h4,
h5,
h6,
p,
blockquote,
pre,
a,
abbr,
acronym,
address,
big,
cite,
code,
del,
dfn,
em,
img,
ins,
kbd,
q,
s,
samp,
small,
strike,
strong,
sub,
sup,
tt,
var,
b,
u,
i,
center,
dl,
dt,
dd,
ol,
ul,
li,
fieldset,
form,
label,
legend,
table,
caption,
tbody,
tfoot,
thead,
tr,
th,
td,
article,
aside,
canvas,
details,
embed,
figure,
figcaption,
footer,
header,
hgroup,
menu,
nav,
output,
ruby,
section,
summary,
time,
mark,
audio,
video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}

/* HTML5 display-role reset for older browsers */
article,
aside,
details,
figcaption,
figure,
footer,
header,
hgroup,
menu,
nav,
section {
  display: block;
}

body {
  line-height: 1;
}

ol,
ul {
  list-style: none;
}

blockquote,
q {
  quotes: none;
}

blockquote:before,
blockquote:after,
q:before,
q:after {
  content: '';
  content: none;
}

table {
  border-collapse: collapse;
  border-spacing: 0;
}



/* --------------------------- */




body {
  background-color: #3d385a;

}

.wrap {
  padding-top: 50px;
  perspective: 1000px;
  height: 100vh;
  transform-style: preserve-3d;
}

.container {
  margin: auto;
  width: 680px;

  display: flex;

  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  transition-duration: 1s;
  transform: rotateX(50deg) rotateZ(-45deg) rotateY(20deg);
  transform-style: inherit;
}

img {
  max-width: 100%;
}

.card {
  width: 200px;
  margin: 10px;
  transition-duration: 0.3s;
}

.card:hover {
  transform: translateZ(10px);
  cursor: pointer;
}

.container-origin {
  transform: rotate(0);
}

/* -=-----=-=-=-=-=-=-=-=-=-=-=-= */

header {

  height: 100px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  
}
.header_fixed{
  position: fixed;
  top: 0%;
  left: 0;
  right: 0;
  padding:10px 0;
  animation:fixedHeader 1s ;
  z-index: 1000;
}
@keyframes fixedHeader{
  0%{
    opacity: 0;
    top:-100px;
  }
  100%{
    opacity: 1;
    top:0;
  }
}

.menu-btn {
  display: inline-block;
  background-color: #fff;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  position: relative;


}

.menu-btn__1 span,
.menu-btn__1 span::before,
.menu-btn__1 span::after {
  position: absolute;
  height: 2px;
  width: 20px;
  top: 50%;
  left: 50%;
  background-color: #222;
  margin-left: -10px;
  margin-top: -1px;
}

.menu-btn__1 span::before,
.menu-btn__1 span::after {
  content: "";
  transition-duration: 0.2s;
}

.menu-btn__1 span::before {
  transform: translateY(-5px);
}

.menu-btn__1 span::after {
  transform: translateY(5px);
}

.menu-btn__1_active span::before {
  transform: rotate(-35deg);
  width: 10px;
  transform-origin: left bottom;
}

.menu-btn__1_active span::after {
  transform: rotate(35deg);
  width: 10px;
  transform-origin: left top;
}

/* 0=-0=--=====--=-=-=-== */
.menu-block {

  border-top-right-radius: 50px;
  border-bottom-right-radius: 50px;
  overflow: hidden;
  display: flex;
  justify-content: center;
  align-items: center;
  transition-duration: 0.5s;
  transform: translateX(-50%);
  position: relative;
  
  
}

.menu-block_active {
  transform: translateX(0);
}

.menu_nav a {
  display: inline-block;
  color: #222;
  text-decoration: none;
  text-transform: uppercase;
  line-height: 50px;
  margin-right: 15px;

}

.menu_nav {
  padding-left: 20px;
  padding-right: 40px;
  background-color: #fff;

  border-radius: 50px;
  transition-duration: 0.5s;
  transform: translateX(100%);
  opacity: 0;
}

.menu_nav_active {
  transform: translateX(45px);
  opacity: 1;
}

/* ---------------------------------- */
.menu-block__2 {
  position: relative;
  margin-right: 10%;

}

.menu_nav__2 a {
  color: #222;
  background-color: #fff;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  z-index: 0;
  border: 1px solid;
  left: 20%;
  top: 20%;
  transition-duration: .3s;
}

.menu_nav__2__active a:nth-child(1) {
  transform: translate(150%, 0%);
  transition-delay: 0.1s;
}

.menu_nav__2__active a:nth-child(2) {
  transform: translate(100%, 100%);
  transition-delay: 0.2s;

}

.menu_nav__2__active a:nth-child(3) {
  transform: translate(0%, 150%);
  transition-delay: 0.3s;

}

.menu-btn__2 span,
.menu-btn__2 span::before,
.menu-btn__2 span::after {
  position: absolute;
  height: 2px;
  width: 20px;
  top: 50%;
  left: 50%;
  background-color: #222;
  margin-left: -10px;
  margin-top: -1px;
}

.menu-btn__2 span::before,
.menu-btn__2 span::after {
  content: "";
  transition-duration: 0.2s;
}

.menu-btn__2 span::before {
  transform: translateY(-5px);
}

.menu-btn__2 span::after {
  transform: translateY(5px);
}

.menu-btn__2__active span {
  height: 0;
}

.menu-btn__2__active span::before {
  transform: rotate(45deg);
}

.menu-btn__2__active span::after {
  transform: rotate(-45deg);
}

/* ////////////////////////////////// */
.happy {
  background-color: #fab1a0;
  height: 400px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.envelope {
  width: 200px;
  height: 110px;
  position: relative;



}

.envelope_top {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  transition-duration: .2s;
  transform: translateY(-100%);
  transform-origin: bottom;
}

.envelope_top__close {
  transform: rotateX(180deg) translateY(110%);
  z-index: 2;
}

.envelope_body {

  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
}

.paper {
  position: absolute;
  background-color: #fff;
  left: 50%;
  margin-left: -25%;
  height: 80px;
  width: 100px;
  text-align: center;
  transition-duration: .2s;
  transform: translateY(-20%);
}

.paper__close {
  transform: translateY(0);
  height: 40px;
}

/* ///////////////////////////////////////// */

.wrap-cardd {
  height: 500px;
  display: flex;
  justify-content: center;
  align-items: center;
}

.cardd {
  cursor: pointer;
  width: 300px;
  height: 300px;

  position: relative;
  perspective: 1000px;

}

.front,
.back {

  position: absolute;
  width: 100%;
  height: 100%;
  left: 0;
  top: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: 1s;
  backface-visibility: hidden;
  border-radius: 15px;

}

.front {
  background-color: #fff;

}

.front::before,
.front::after {
  content: "";
  left: 5%;
  right: 5%;
  top: 5%;
  bottom: 5%;

  transition-duration: .5s;
  position: absolute;

}

.front::before {
  transform: scaleX(0);
  border-top: 2px solid black;
  border-bottom: 2px solid black;
}

.front::after {
  transform: scaleY(0);
  border-right: 2px solid black;
  border-left: 2px solid black;
}

.front:hover:before {
  transform: scaleX(1);
}

.front:hover:after {
  transform: scaleY(1);
}

.back {
  background-color: #00796B;
  transform: rotateY(180deg);

}

.front_active {
  transform: rotateY(180deg)
}

.back_active {
  transform: rotateY(360deg)
}

/* ////////////////////// */
.container-btn{
  height: 300px;
  background-color: grey;
  display: flex;
  justify-content: center;
  align-items: center;
  
}
.btn {
  position: relative;
  display: inline-block;
  text-decoration: none;
  background-color: tomato;
  color: #fff;
  padding: 10px 20px;
  border-radius: 5px;
  overflow: hidden;
}
.btn:before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 1.5em;
  height: 100%;
  background-color: rgba(255, 255, 255, 0.6);
  transform: translateX(-4em) skewX(-45deg);
}
.btn:hover:before {
  animation: move-light 0.5s;
}

@keyframes move-light {
  from {
    transform: translateX(-4em) skewX(-45deg);
  }
  to {
    transform: translateX(10em) skewX(-45deg);
  }
}