*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-image: linear-gradient(180deg, royalblue, rgba(255, 0, 76, 0.911));
}

#img{
    height: 100%;
    width: 100%;
    border-radius: 16px;
    
}

.main{
    max-width: 600px;
    width: 95%;
    position: absolute;
    border: 2px solid black;
    border-radius: 16px;
    box-shadow: rgba(6, 24, 44, 0.4) 0px 0px 0px 2px, rgba(6, 24, 44, 0.65) 0px 4px 6px -1px, rgba(255, 255, 255, 0.08) 0px 1px 0px inset;
}

&::after{
  content: '';
  display: block;
  padding-top:calc(100% / (9/16));
}

.box{
    width: 100%;
    display: flex;
    justify-content: center;
}

/* CSS */
.btnext {
  align-items: center;
  appearance: none;
  background-image: radial-gradient(100% 100% at 100% 0, #5adaff 0, #5468ff 100%);
  border: 0;
  border-radius: 6px;
  box-shadow: rgba(45, 35, 66, .4) 0 2px 4px,rgba(45, 35, 66, .3) 0 7px 13px -3px,rgba(58, 65, 111, .5) 0 -3px 0 inset;
  box-sizing: border-box;
  color: #fff;
  cursor: pointer;
  display: inline-flex;
  font-family: "JetBrains Mono",monospace;
  height: 48px;
  justify-content: center;
  line-height: 1;
  list-style: none;
  overflow: hidden;
  padding-left: 16px;
  padding-right: 16px;
  position: relative;
  text-align: left;
  text-decoration: none;
  transition: box-shadow .15s,transform .15s;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  white-space: nowrap;
  will-change: box-shadow,transform;
  font-size: 18px;
  margin: 10px 11px;
}

.btnext:focus {
  box-shadow: #3c4fe0 0 0 0 1.5px inset, rgba(45, 35, 66, .4) 0 2px 4px, rgba(45, 35, 66, .3) 0 7px 13px -3px, #3c4fe0 0 -3px 0 inset;
}

.btnext:hover {
  box-shadow: rgba(45, 35, 66, .4) 0 4px 8px, rgba(45, 35, 66, .3) 0 7px 13px -3px, #3c4fe0 0 -3px 0 inset;
  transform: translateY(-2px);
}

.btnext:active {
  box-shadow: #3c4fe0 0 3px 7px inset;
  transform: translateY(2px);
}

CSS
.share_res {
  align-items: center;
  appearance: none;
  background-image: radial-gradient(100% 100% at 100% 0, #5adaff 0, #5468ff 100%);
  border: 0;
  border-radius: 6px;
  box-shadow: rgba(45, 35, 66, .4) 0 2px 4px,rgba(45, 35, 66, .3) 0 7px 13px -3px,rgba(58, 65, 111, .5) 0 -3px 0 inset;
  box-sizing: border-box;
  color: #fff;
  cursor: pointer;
  display: inline-flex;
  font-family: "JetBrains Mono",monospace;
  height: 48px;
  justify-content: center;
  line-height: 1;
  list-style: none;
  overflow: hidden;
  padding-left: 16px;
  padding-right: 16px;
  position: relative;
  text-align: left;
  text-decoration: none;
  transition: box-shadow .15s,transform .15s;
  user-select: none;
  -webkit-user-select: none;
  touch-action: manipulation;
  white-space: nowrap;
  will-change: box-shadow,transform;
  font-size: 18px;
  margin: 10px 11px;
}

.share_res:focus {
  box-shadow: #3c4fe0 0 0 0 1.5px inset, rgba(45, 35, 66, .4) 0 2px 4px, rgba(45, 35, 66, .3) 0 7px 13px -3px, #3c4fe0 0 -3px 0 inset;
}

.share_res:hover {
  box-shadow: rgba(45, 35, 66, .4) 0 4px 8px, rgba(45, 35, 66, .3) 0 7px 13px -3px, #3c4fe0 0 -3px 0 inset;
  transform: translateY(-2px);
}

.share_res:active {
  box-shadow: #3c4fe0 0 3px 7px inset;
  transform: translateY(2px);
}