Local fonts.

css/theme/latex.css

@@ -1,6 +1,5 @@
 @charset "UTF-8";
 /* tame reveal.js */
-@import url("https://free.bboxtype.com/embedfonts/?family=FiraSans:300,600");
 section {
   min-height: 100vh;
   width: 100vw;
@@ -75,6 +74,16 @@ body {
       box-shadow: 0.2em 0.2em 0.5em 0 rgba(0, 0, 0, 0.3); }
 
 /* content layout */
+@font-face {
+  font-family: 'Fira Sans';
+  src: url("../../lib/font/fira-sans/FiraSans-Regular.ttf");
+  font-weight: 400; }
+
+@font-face {
+  font-family: 'Fira Sans';
+  src: url("../../lib/font/fira-sans/FiraSans-Bold.ttf");
+  font-weight: 700; }
+
 @font-face {
   font-family: 'Fira Code';
   src: url("../../lib/font/fira-code/FiraCode-Regular.otf");

css/theme/source/latex.scss

@@ -110,7 +110,16 @@ body {
 
 /* content layout */
 
-@import url('https://free.bboxtype.com/embedfonts/?family=FiraSans:300,600');
+@font-face {
+  font-family: 'Fira Sans';
+  src: url('../../lib/font/fira-sans/FiraSans-Regular.ttf');
+  font-weight: 400;
+}
+@font-face {
+  font-family: 'Fira Sans';
+  src: url('../../lib/font/fira-sans/FiraSans-Bold.ttf');
+  font-weight: 700;
+}
 @font-face {
   font-family: 'Fira Code';
   src: url('../../lib/font/fira-code/FiraCode-Regular.otf');
@@ -121,6 +130,7 @@ body {
   src: url('../../lib/font/fira-code/FiraCode-Bold.otf');
   font-weight: 700;
 }
+
 body {
   font-family: 'Fira Sans';
   margin: 0;