* {
    box-sizing: border-box;
}
body {
    font-family: Verdana, serif;
    background: #ffffff;
    margin: 15px;
    font-size: 0.9em;
}
header {
    border: 2px solid black;
    border-radius: 1em;
    padding: 10px 20px;
    box-shadow: rgba(0, 0, 0, 0.2) 3px 3px 5px;
    background: #f0f0f0;
}

input {
    margin-top: 5px;
    margin-bottom: 5px;
    width: 30%;
    border: black 2px solid;
    border-radius: 0.5em;
    height: 2em;
}

button {
    padding: 5px;
    width: 30%;
    border: black 2px solid;
    border-radius: 0.5em;
    font-weight: bold;
    margin-top: 5px;
}
pre {
    font-family: Verdana, serif;
}

.box {
    border: 2px solid black;
    padding: 15px 20px;
    border-radius: 1em;
    margin: 15px 0 10px 0;
    box-shadow: rgba(0, 0, 0, 0.2) 3px 3px 5px;
}

.box h3 {
    cursor: pointer;
}
td {
    width: 50px;
    height: 50px;
    margin: 0;
    padding: 0;
}
tr {
    padding: 0;
}

.y {
    background: yellow;
}

.b {
    background:blue;
}
.aloneButton {
    margin: 0;
}