.wrapper {
  display: grid;
  grid-template-columns: 35% 30% 35%;
}
.box {
padding-top: 20px; 
  text-align: center;
}

h3, h4 {

text-align: center;

}


p {

border-style: hidden;   /* this seems required to allow padding for narrow windows */
max-width: 800px;
margin: auto;
padding: 8px; 
text-indent: 30px;

font-size: 1.2em;

}

p.eq{            /* class for equations */    

text-align: center; 

padding: 0px; 
text-indent: 0px;

}

p.ref{            /* class for references */    

text-indent: 0px;

}

p.ex{            /* class for examples */    

text-indent: 0px;

}

div.cen{      /* centres all with class "cen" */              

text-align: center; 

}

table, td, th {
  border: 1px solid black;
}

table {
  border-collapse: collapse;
  width: 80%;
}

th {
  height: 50px;
}


#shwBtt {  /* show wavefunctions button */
font-size: 0.8em; 
background-color: white;
color: black;
border: 1px solid;
border-radius: 16px;
}