SOURCE

<div id="main">ada</div>
<div id="main">ada</div>

@media screen and(min-width: 320px)and(max-width: 359px){ 
html{ 
font-size: 12.8px; 
} 
} 
@media screen and(min-width: 360px)and(max-width: 374px){ 
html{ 
font-size: 14.4px; 
} 
} 
@media screen and(min-width: 375px)and(max-width: 385px){ 
html{ 
font-size: 15px; 
} 
} 
@media screen and(min-width: 386px)and(max-width: 392px) { 
html { 
font-size: 15.44px; 
} 
} 
@media screen and(min-width: 393px)and(max-width: 400px){ 
html{ 
font-size: 16px; 
} 
} 
@media screen and(min-width: 401px)and(max-width: 414px){ 
html{ 
font-size: 16.48px; 
} 
} 
@media screen and(min-width: 750px)and(max-width: 799px){ 
html{ 
font-size: 30.72px; 
} 
}