body { margin:0; font-family: Arial, sans-serif; background:#000; color:#fff; }
header { padding:10px; background:#111; text-align:center; }
main { display:flex; height: calc(100vh - 50px); }
aside { width:260px; overflow-y:auto; background:#141414; }
aside div { padding:10px; cursor:pointer; border-bottom:1px solid #222; }
aside div:hover { background:#222; }
#player { flex:1; display:flex; align-items:center; justify-content:center; }
video { width:100%; height:100%; background:#000; }