joplin/packages/app-desktop/style/icons/style.css

@font-face {
  font-family: 'icomoon';
  src:  url('fonts/icomoon.eot?f410v3');
  src:  url('fonts/icomoon.eot?f410v3#iefix') format('embedded-opentype'),
    url('fonts/icomoon.ttf?f410v3') format('truetype'),
    url('fonts/icomoon.woff?f410v3') format('woff'),
    url('fonts/icomoon.svg?f410v3#icomoon') format('svg');
  font-weight: normal;
  font-style: normal;
  font-display: block;
}

[class^="icon-"], [class*=" icon-"] {
  /* use !important to prevent issues with browser extensions that change fonts */
  font-family: 'icomoon' !important;
  speak: never;
  font-style: normal;
  font-weight: normal;
  font-variant: normal;
  text-transform: none;
  line-height: 1;

  /* Better Font Rendering =========== */
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.icon-error:before {
  content: "\e900";
}
.icon-attention:before {
  content: "\e901";
}
.icon-collapse:before {
  content: "\e902";
}
.icon-cancel:before {
  content: "\e903";
}
.icon-expand:before {
  content: "\e904";
}
.icon-notebooks:before {
  content: "\e905";
}
.icon-plus:before {
  content: "\e906";
}
.icon-update:before {
  content: "\e907";
}
.icon-tags:before {
  content: "\e908";
}
.icon-search:before {
  content: "\e909";
}
.icon-notes:before {
  content: "\e90a";
}
.icon-sync:before {
  content: "\e90b";
}
.icon-general:before {
  content: "\e90c";
}
.icon-note:before {
  content: "\e90d";
}
.icon-note-history:before {
  content: "\e90e";
}
.icon-application:before {
  content: "\e90f";
}
.icon-encryption:before {
  content: "\e910";
}
.icon-plugins:before {
  content: "\e911";
}
.icon-web-clipper:before {
  content: "\e912";
}
.icon-appearance:before {
  content: "\e913";
}
.icon-code:before {
  content: "\e914";
}
.icon-asterisks:before {
  content: "\e915";
}
.icon-bold:before {
  content: "\e916";
}
.icon-bulleted-list:before {
  content: "\e917";
}
.icon-embed-code:before {
  content: "\e918";
}
.icon-back:before {
  content: "\e919";
}
.icon-forward:before {
  content: "\e91a";
}
.icon-h1:before {
  content: "\e91b";
}
.icon-h2:before {
  content: "\e91c";
}
.icon-h3:before {
  content: "\e91d";
}
.icon-heading:before {
  content: "\e91e";
}
.icon-info:before {
  content: "\e91f";
}
.icon-italic:before {
  content: "\e920";
}
.icon-layout:before {
  content: "\e921";
}
.icon-line:before {
  content: "\e922";
}
.icon-link:before {
  content: "\e923";
}
.icon-more:before {
  content: "\e924";
}
.icon-numbered-list:before {
  content: "\e925";
}
.icon-quote:before {
  content: "\e926";
}
.icon-alarm:before {
  content: "\e927";
}
.icon-share:before {
  content: "\e928";
}
.icon-table:before {
  content: "\e929";
}
.icon-to-do-list:before {
  content: "\e92a";
}
.icon-add-date:before {
  content: "\e92b";
}
.icon-attachment:before {
  content: "\e92c";
}