Source Sans Pro in action on notion.ai

Under the hood

.header-1 { font-family: "Source Sans Pro", sans-serif; font-size: 52px; font-style: normal; font-weight: 200; letter-spacing: normal; line-height: 63px; text-transform: none; color: #664897; }
.content-1 { font-family: "Source Sans Pro", sans-serif; font-size: 20px; font-style: normal; font-weight: 300; letter-spacing: normal; line-height: 27px; text-transform: none; color: #424154; }