HTML, CSS and JavaScript playground

.heart-beat {
  position: relative;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(8, 1fr);
  grid-template-areas:
    "a1 a2 a3 a4 a5 a6 a7 a8 a9"
    "b1 b2 b3 b4 b5 b6 b7 b8 b9"
    "c1 c2 c3 c4 c5 c6 c7 c8 c9"
    "d1 d2 d3 d4 d5 d6 d7 d8 d9"
    "e1 e2 e3 e4 e5 e6 e7 e8 e9"
    "f1 f2 f3 f4 f5 f6 f7 f8 f9"
    "g1 g2 g3 g4 g5 g6 g7 g8 g9"
    "h1 h2 h3 h4 h5 h6 h7 h8 h9";
  margin: auto;
  width: 302px;
  background: black;
  color: #fff;
  gap:4px;
  border: 66px solid #000;
  border-right: 49px solid #000;
  border-left: 49px solid #000;
}

.heart-beat p{
  margin: 0;
  aspect-ratio: 1 /1;
  background: red;
  display:flex;
  align-items:center;
  justify-content:center;

}
p:nth-child(1) {grid-area: a2;background:green;}
p:nth-child(2) {grid-area: a3;background:green;}
p:nth-child(3) {grid-area: a7;background:green;}
p:nth-child(4) {grid-area: a8;background:green;}
p:nth-child(5) {grid-area: b1;background:green;}
p:nth-child(6) {grid-area: b2;}
p:nth-child(7) {grid-area: b3;}
p:nth-child(8) {grid-area: b4;background:green;}
p:nth-child(9) {grid-area: b6;background:green;}
p:nth-child(10) {grid-area: b7;}
p:nth-child(11) {grid-area: b8;}
p:nth-child(12) {grid-area: b9;background:green;}
p:nth-child(13) {grid-area: c1;background:green;}
p:nth-child(14) {grid-area: c2;}
p:nth-child(15) {grid-area: c3;}
p:nth-child(16) {grid-area: c4;}
p:nth-child(17) {grid-area: c5;background:green;}
p:nth-child(18) {grid-area: c6;}
p:nth-child(19) {grid-area: c7;}
p:nth-child(20) {grid-area: c8;}
p:nth-child(21) {grid-area: c9;background:green;}
p:nth-child(22) {grid-area: d1;background:green;}
p:nth-child(23) {grid-area: d2;}
p:nth-child(24) {grid-area: d3;}
p:nth-child(25) {grid-area: d4;}
p:nth-child(26) {grid-area: d5;}
p:nth-child(27) {grid-area: d6;}
p:nth-child(28) {grid-area: d7;}
p:nth-child(29) {grid-area: d8;}
p:nth-child(30) {grid-area: d9;background:green;}
p:nth-child(31) {grid-area: e2;background:green;}
p:nth-child(32) {grid-area: e3;}
p:nth-child(34) {grid-area: e4;}
p:nth-child(35) {grid-area: e4;}
p:nth-child(36) {grid-area: e4;}
p:nth-child(32) {grid-area: e3;}
p:nth-child(33) {grid-area: e4;}
p:nth-child(33) {grid-area: e4;}
p:nth-child(33) {grid-area: e4;}
p:nth-child(33) {grid-area: e4;}
p:nth-child(34) {grid-area: e5;}
p:nth-child(35) {grid-area: e6;}
p:nth-child(36) {grid-area: e7;}
p:nth-child(37) {grid-area: e8;background:green;}
p:nth-child(38) {grid-area: f3;background:green;}
p:nth-child(39) {grid-area: f4;}
p:nth-child(39) {grid-area: f4;}
p:nth-child(40) {grid-area: f5;}
p:nth-child(41) {grid-area: f6;}
p:nth-child(42) {grid-area: f7;background:green;}
p:nth-child(43) {grid-area: g4;background:green;}
p:nth-child(44) {grid-area: g5;}
p:nth-child(45) {grid-area: g6;background:green;}
p:nth-child(46) {grid-area: h5;background:green;}