Apple System with UI Serif in action on manus.im

Under the hood

.content-1 { font-family: -apple-system, "system-ui", "Segoe UI Variable Display", "Segoe UI", Helvetica, "Apple Color Emoji", Arial, sans-serif, "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 20px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 30px; text-transform: none; color: #666666; }
.content-2 { font-family: ui-serif, LibreBaskerville, Georgia, Cambria, "Times New Roman", Times, serif; font-size: 64px; font-style: normal; font-weight: 500; letter-spacing: normal; line-height: 70px; text-transform: none; color: #000000; }