styles.css

@keyframes shake {
  0% {
    transform: rotate(0deg);
  }
  20% {
    transform: rotate(-20deg);
  }
  40% {
    transform: rotate(20deg);
  }
  60% {
    transform: rotate(-10deg);
  }
  80% {
    transform: rotate(10deg);
  }
  100% {
    transform: rotate(0deg);
  }
}
html, body {
}
body {
  background-color: white;
  display: flex;
  align-items: center;
  font-family: 'Helvetica';
}
main {
  text-align: center;
  -webkit-flex-flow: row wrap;
  -moz-flex-flow: row wrap;
  -ms-flex-flow: row wrap;
  flex-flow: row wrap;
  position: relative
}
.present {
  position: relative;
  display: inline-block;
  width: 14em;
  height: 14em;
  margin: 0.5em;
  perspective: 850px;
  z-index: 666;
  flex:1;
}
.present__pane, .present__content {
  width: inherit;
  height: inherit;
}
.present__pane {
  position: relative;
  background: linear-gradient(45deg,#1b71af,#55a9e5);
  transform-style: preserve-3d;
  transform-origin: 0;
  perspective: 850px;
  text-align: center;
  box-shadow: 0 0 40px 0 rgba(0, 0, 0, .15);
  cursor: pointer;
  transition: all 0.2s ease-out;
}
.present__date {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 2.4em;
  height: 2.4em;
  margin: 0;
  font-size: 2em;
  line-height: 2.4em;
  background: #e2f1ff;
  color: #e22222;
  border-radius: 50%;
  box-shadow: inset 0 0 10px 5px #6b98c3;
}

.present:hover {
  z-index: 999;
}

.present:hover .present__pane {
  background: linear-gradient(45deg,#43b0ff,#c3e6ff);
  transform: rotateY(-97deg);
  perspective-origin: 0;
  transition: all 0.25s ease-in;
}
.present:hover .present__date {
  backface-visibility: hidden;
}
.present:hover .present__bauble {
  display: inline-block;
  transform-origin: 50% 0;
  animation: shake 0.7s;
}
.present__content {
  position: absolute;
  top: 0;
  left: 0;
  background: #ff8a24;
  box-shadow: 0 0 40px 0 rgba(0, 0, 0, .15), inset 0 0 30px 20px rgba(0, 0, 0, .15);
  z-index: -1;
  /*firefox fix*/
  overflow: hidden;
}
.present__bauble {
  position: relative;
  width: 2.66667em;
  height: 2.66667em;
  background: Violet;
  margin: 25% auto 0 auto;
  font-size: 2.66667em;
  line-height: 2.66667em;
  border-radius: 50%;
}

.present__bauble::after {
  content: '';
  position: absolute;
  top: -5%;
  left: 50%;
  width: 30%;
  height: 10%;
  margin-left: -15%;
  background: inherit;
}

.present__bauble::before {
  content: '';
  position: absolute;
  top: -15%;
  left: 50%;
  width: 12%;
  height: 20%;
  margin-left: -12%;
  border: 0.35rem solid Violet;
  border-radius: 50%;
  z-index: 0;
}

.present-background {
  height: 100%;
  width:100%;
  background: url(./img/datawatch-bulles.png);
  position:absolute;
  overflow: hidden;
  top:0;
}

.present-textStyle {
  margin: 0 1.5em 0 1.5em;
  color:white;
}

/* Cancel animation style */
.removeAnimation {
  -o-transition-property: none !important;
  -moz-transition-property: none !important;
  -ms-transition-property: none !important;
  -webkit-transition-property: none !important;
  transition-property: none !important;
  /*CSS transforms*/
  -o-transform: none !important;
  -moz-transform: none !important;
  -ms-transform: none !important;
  -webkit-transform: none !important;
  transform: none !important;
  /*CSS animations*/
  -webkit-animation: none !important;
  -moz-animation: none !important;
  -o-animation: none !important;
  -ms-animation: none !important;
  animation: none !important;
}
/* Flexbox */

.safari-flexbox {
  display: -webkit-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: -webkit-flexbox;
  -ms-flex-direction: flex;
}

.flexbox-row {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: horizontal;
  -webkit-box-direction: normal;
  -ms-flex-direction: row;
  flex-direction: row;
}

.flexbox-column {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -ms-flex-direction: column;
  flex-direction: column;
}

.flexbox-space-around {
  -ms-flex-pack: distribute;
  -webkit-justify-content: space-around;
  justify-content: space-around;
}

.flexbox-space-between {
  -webkit-box-pack: justify;
  -ms-flex-pack: justify;
  -webkit-justify-content: space-between;
  justify-content: space-between;
}

.flexbox-center {
  -webkit-box-align: center;
  -ms-flex-align: center;
  -webkit-align-items: center;
  align-items: center;
}

.flexbox-flex-end {
  -webkit-box-align: end;
  -ms-flex-align: end;
  -webkit-align-items: flex-end;
  align-items: flex-end;
}

.flexbox-justify-center {
  -webkit-box-pack:center;
  -ms-flex-pack:center;
  -webkit-justify-content: center;
  justify-content:center;
}


/* Template data.gouv */
.hero {
    width: 100%;
    background-color: #ebeff3;
    background-blend-mode: darken;
    background-image: url(./img/background.jpg);
    background-size: cover;
    background-repeat: no-repeat;
    background-position: 50%;
    background-attachment: fixed;
}
.hero__container {
    height: 38vh;
    display: -webkit-box;
    display: -ms-flexbox;
    display: flex;
    -webkit-box-orient: vertical;
    -webkit-box-direction: normal;
    -ms-flex-direction: column;
    flex-direction: column;
    -webkit-box-pack: center;
    -ms-flex-pack: center;
    justify-content: center;
    -webkit-box-align: center;
    -ms-flex-align: center;
    align-items: center;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

.hero h1 {
    color: #26353f;
    margin: 0;
}
.hero h1 {
    color: #26353f;
    margin: 0;
}

.hero__white-background {
    padding: 10px 1em;
    background-color: #fff;
}

.hero__white-background {
    padding: 10px 1em;
    background-color: #fff;
}