* {
    box-sizing: border-box !important;
}

html {
    font-size: 62.5%;
}

body {
    margin: 0;
    padding: 0;
    background: #233637;
    height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.card {
    width: 0;
    height: 0;
    border-top: 10rem solid #eee;
    border-right: 17rem solid #ddd;
    border-bottom:  10rem solid #ccc;
    border-left: 17rem solid #ccc;
}

.heart {
   width: 3.2rem;
   height: 3.2rem;
   background-color: red; 
   transform: translate(-50%, -50%) rotate(45deg);
   animation: heartbeat 1.4s linear infinite;
}

.heart::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: red;
    transform: translate(0,-50%);
    border-top-left-radius: 50%;
    border-top-right-radius: 50%;    
}

.heart::after {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: red;
    transform: translate(-50%, 0);
    border-top-left-radius: 50%;
    border-bottom-left-radius: 50%;
}

@keyframes heartbeat {
    0% { transform: translate(-50%, -50%) rotate(45deg) scale(1); }
    25% { transform: translate(-50%, -50%) rotate(45deg) scale(1); }
    30% { transform: translate(-50%, -50%) rotate(45deg) scale(1.4); }
    50% { transform: translate(-50%, -50%) rotate(45deg) scale(1.2); }
    70% { transform: translate(-50%, -50%) rotate(45deg) scale(1.4); }
    100% { transform: translate(-50%, -50%) rotate(45deg) scale(1); }
}