:root {
    --bg: #ffffff;
    --text: #000000;
    --card: #f3f3f3;
}

.dark-mode {
    --bg: #121212;
    --text: #ffffff;
    --card: #1f1f1f;
}

.tool-wrapper {
    background: var(--bg);
    color: var(--text);
    max-width: 500px;
    margin: auto;
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 0 15px rgba(0,0,0,0.15);
    font-family: Arial, sans-serif;
}

.tool-wrapper h2 {
    text-align: center;
    margin-bottom: 20px;
}

.tool-wrapper input, 
.tool-wrapper select {
    width: 100%;
    padding: 12px;
    margin-top: 8px;
    margin-bottom: 15px;
    border-radius: 8px;
    border: 1px solid #ccc;
    font-size: 15px;
    background: var(--card);
    color: var(--text);
}

.tool-wrapper button {
    width: 100%;
    padding: 12px;
    background: #007bff;
    border: none;
    color: white;
    font-size: 16px;
    border-radius: 8px;
    cursor: pointer;
    margin-top: 8px;
}

.tool-wrapper button:hover {
    background: #0056b3;
}

#resultBox {
    margin-top: 20px;
    padding: 15px;
    background: var(--card);
    border-radius: 10px;
    font-size: 22px;
    font-weight: bold;
    text-align: center;
}

#formulaDisplay {
    margin-top: 10px;
    padding: 12px;
    border-left: 4px solid #007bff;
    background: var(--card);
    font-size: 14px;
}

.theme-toggle {
    background: #444;
    margin-bottom: 15px;
}