Letter I
I solved it on September 23, 2022. You can try to beat my record on CSSBattle!
526 chars
<body bgcolor=E3516E><p c><p b><p a><p s><style>p{background:#FADE8B;position:absolute}p:after{content:"";position:absolute;inset:0;transform:rotate(180deg);border-radius:16px}[c]{padding:15;border-radius:50%;margin:62 252}[c]:after{border-radius:50%;box-shadow:150px -130px 0 0 #FADE8B}[b]{margin:62 142;padding:15 50;border-radius:16px}[b]:after{box-shadow:0px -130px 0 0 #FADE8B}[a]{margin:92 170;padding:50 22}[s]{margin:92 207;padding:50 10;border-radius:10px;background:#E3516E}[s]:after{box-shadow:50px 0px 0 0 #E3516E}