#tkc-calculator {
    max-width:700px;
    margin:30px auto;
    padding:25px;
    background:#fff;
    border-radius:10px;
    box-shadow:0 6px 20px rgba(0,0,0,0.08);
    font-family:Arial, sans-serif;
}

#tkc-calculator h2 {
    text-align:center;
    color:#1a3c6e;
}

#tkc-calculator select,
#tkc-calculator input,
#tkc-calculator button {
    width:100%;
    padding:10px;
    margin-top:5px;
    border-radius:6px;
    border:1px solid #ccc;
    box-sizing:border-box;
}

#tkc-calculator button {
    background:#1a3c6e;
    color:#fff;
    font-size:16px;
    cursor:pointer;
    margin-top:20px;
}

#tkc-resultBox {
    display:none;
    margin-top:20px;
    padding:15px;
    background:#eef3fa;
    border-radius:8px;
    text-align:center;
}

#tkc-resultBox #tkc-kvaResult {
    font-size:20px;
    color:#0a7d2c;
    font-weight:bold;
}

.tkc-formula {
    margin-top:15px;
    font-size:13px;
    color:#666;
}