body {
    background: lightblue;
    color: blue;
    font-family: serif;
    text-align: center;
}

h1 {
    font-size: 2rem;
}

#container {
    margin: 5% auto;
    border-radius: 5px;
    text-align: center;
}

.box {
    display: inline-block;  
    border: 1px solid blue;
    width: 100px;
    height: 100px;
    text-align: center;
    box-sizing: border-box;
    padding: 0;
}

span {
    position: absolute;
    font-size: 75px;
    font-family: sans-serif;
    text-align: center;
    height: 75px;
    width: 75px;
    padding: 0;
    margin: 5px;
    margin-left: -35px;
}

.top {
    border-top: none;   /* rimuovo il bordo superiore */
}

.bottom {
    border-bottom: none;
}

.left {
    border-left: none;
}

.right {
    border-right: none;
}

.alert {
    height: 75px;
    width: 125px;
    display: inline-block;
    background: ghostwhite;
    position: relative;
    z-index: 10;    /* l'element con valore maggiore viene posizionato sopra quello minore */
    margin-top: -50%;
    border-radius: 20px;
    box-shadow: 0 0 75px 2px dimgray;
    animation: larger 0.5s;
    animation-fill-mode: forwards;  /* l'elemento mantiene lo stat finale dopo l'animazione */
    box-sizing: content-box;
    padding: 30px;
    bottom: 50px;
    top: 0;
}

button {
    background: lightyellow;
    border-radius: 10px;
    border: 2px solid blue;
    outline: none;
    margin: 5px;
    padding: 6px;
    font-weight: bold;
    color: black;
}

button:focus {
    background: silver;
}

.activeBox {
    background: silver;
}

@keyframes larger{  /* animazione che cambia nel tempo chiamata larger */
    from{
        height: 75px;
        width: 125px;
    }

    to{
        height: 100px;
        width: 250px;
    }

}

.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
}

.modal-content {
    background-color: #fefefe;
    margin: 10% auto;
    padding: 20px;
    border: 1px solid #888;
    width: 80%;
}

.close {
    color: #aaa;
    float: right;
    font-size: 28px;
    font-weight: bold;
    cursor: pointer;
}

.close:hover {
    color: black;
}