Move to use REM with 62.5% trick

src/components/App/index.scss

@@ -2,12 +2,14 @@
 
 html {
     background: $bg-color;
+    font-size: 62.5%;
     padding: $unit * 2;
 }
 
 body {
     font-family: system-ui, -apple-system, Helvetica Neue, Helvetica, Arial, sans-serif;
 
+    font-size: 1.4rem;
     &.no-scroll {
         overflow: hidden;
     }
@@ -23,6 +25,7 @@ h1, h2, h3, p {
 
 h1 {
     font-size: 18px;
+    font-size: 2.1rem;
     font-weight: 500;
     text-align: center;
 }

src/components/Segment/index.scss

@@ -3,6 +3,7 @@
     color: #888;
     cursor: pointer;
     font-size: 16px;
+    font-size: 1.4rem;
     font-weight: 500;
     min-width: 100px;