body {
    font-family: Arial, sans-serif;
    max-width: 90%;
    margin: 20px auto;
    padding: 20px;
    background: #f7f7f7;
    border-radius: 20px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

h1, h2 {
    text-align: center;
}

label {
    display: block;
    margin-top: 20px;
}

input, button {
    font-size: 1em;
}

input {
    width: 100%;
    padding: 8px;
    border-radius: 18px;
    border: 1px solid #ccc;
    margin-top: 10px;
}

button {
    margin-top: 20px;
    width: 100%;
    padding: 10px;

    background: #0078ff;
    color: white;

    border: none;
    border-radius: 12px;
    cursor: pointer;
}

button:hover {
    background: #005fcc;
}
.result {
    margin-top: 20px;
    text-align: center;
    font-size: 1.1em;
    font-weight: bold;
}

.formula {
    text-align: center;
    font-size: 1.2em;
    margin-bottom: 20px;
    padding: 1px;
    background: white;
    border-radius: 12px;
    box-shadow: 0 0 5px rgba(0,0,0,0.3);
}

.zscore {
    padding: 10px;
    margin-bottom: 20px;
    border: 1px solid #ccc;
    border-radius: 12px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease;
}

.tgl-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 10px 20px;
    font-size: 1.1em;
    font-weight: bold;
    background: #0078ff;
    color: white;
    border: none;
    border-radius: 12px;
    cursor: pointer;
    transition: background 0.3s, transform 0.3s;
    box-shadow: 0 4px 6px rgba(0,0,0,0.2);
}

.tgl-btn:hover {
    background: #005fcc;
}

.tgl-btn .arrow {
    display: inline-block;
    transition: transform 0.3s;
}

.tgl-btn.active .arrow {
    transform: rotate(180deg);
}