[data-letters]:before {
    content: attr(data-letters);
    display: inline-block;
    font-size: 2em;
    width: 4em;
    height: 4em;
    line-height: 4em;
    text-align: center;
    border-radius: 50%;
    background: var(--bg-color);
    vertical-align: middle;
    color: var(--text-color);
}

/* Reset default styles of iOS */
input[type="submit"],
input[type="button"] {
    border-radius: 0;
    -webkit-box-sizing: content-box;
    -webkit-appearance: button;
    appearance: button;
    border: none;
    box-sizing: border-box;
    cursor: pointer;
}
input[type="submit"]::-webkit-search-decoration,
input[type="button"]::-webkit-search-decoration {
    display: none;
}
input[type="submit"]:focus,
input[type="button"]:focus {
    outline-offset: -2px;
}