.hidden {
    display: none;
}

.equation {
   text-align: center;
}

.item, .divider, .formula {
    display: inline-block;
    margin: 0.3em;
    vertical-align: baseline;
}

.koeficient {
    width: 1.5em;
    padding: 0.2em;
}

.invalid {
 color: darkorange;	
}

.koeficient.invalid {
    border: 1px solid orange;
   
    background-color: #ffd;
}



sup {
    vertical-align: 0.6em;
}

.nad1 {
    margin-left: -0.6em;
}


.correct {
    color: green;
}

.wrong {
    color: red;    
}

.correct::before, .wrong::before {
    font-size: 200%;
    display: inline-block;
    margin-right: 0.5em;
    vertical-align: middle;
}

.correct::before {
    content: "✔";
    
}

.wrong::before {
    content: "✘";
   
}