Custom font on squarespace

Site URL: https://multiple.squarespace.com/

Password: multiple

Trying to add custom font to my site, but doesnt seem to be working.

@font-face {    
font-family: 'plain-light';       
src: url('https://static1.squarespace.com/static/62483097c1382a31a425fc9f/t/625ad635f09aa718b77b6493/1650120245222/plain-light-webfont.ttf');  }

h1 {font-family: 'plain-light';
letter-spacing:-2px;    
font-size:80px; 
line-height: 1.;
  }

p {
font-family: 'plain-light';
}