body{
font-family:Arial,Helvetica,sans-serif;
margin:0;
background:#0b2a6b;
color:white;
}

.cover{
text-align:center;
padding:60px;
}

.logo{
max-width:320px;
}

button{
background:#1e6cff;
border:none;
padding:15px 25px;
color:white;
font-size:18px;
border-radius:8px;
cursor:pointer;
}

#app{
display:flex;
}

nav{
width:220px;
background:#091f4f;
height:100vh;
overflow:auto;
padding:10px;
}

nav div{
padding:10px;
cursor:pointer;
border-bottom:1px solid #234;
}

#lesson{
flex:1;
padding:30px;
font-size:20px;
line-height:1.7;
}

.word{
margin-right:6px;
cursor:pointer;
}

.speaker{
margin-left:4px;
cursor:pointer;
}
.hidden{
display:none;
}