body { 
    background-color: black;
    color: white;
}

h1 {
    border: 1px solid white;
    border-radius: 3px;
    background-color: white;
    color: black;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    text-align: center;
}

.main-content {
    display: flex;
    justify-content: space-between;
}

.input-output-area {
    border: 1px solid white;
    border-radius: 3px;
    padding: 5px;
    margin-bottom: 5px;
}

.input-output-container {
    flex: 1;
    margin-right: 20px;
    padding: 5px;
}

textarea {
    width: 90%;
    height: 200px;
    margin-bottom: 20px;
}

.output-container {
    margin-bottom: 20px;
}

.substitution-container {
    display: flex;
    justify-content: center;
    overflow-x: auto;
    border: 1px solid white;
    border-radius: 3px;
    padding: 5px;

}

.substitution-box {
    margin: 5px;
    text-align: center;
    display: inline-block;
    border: 1px solid white;
    border-radius: 3px;
}

.substitution-box label {
    display: block;
}

.substitution-box input {
    width: 30px;
    height: 30px;
    text-align: center;
}

.frequency-container {
    width: 200px;
    border: 1px solid white;
    border-radius: 3px;
    padding: 5px;
}

.frequency-container table {
    width: 100%;
    border-collapse: collapse;
}

.frequency-container th, .frequency-container td {
    border: 1px solid white;
    padding: 5px;
    text-align: center;
    border-radius: 3px;
}