:root {
    --primary-color: #2563eb;
    --primary-light: #3b82f6;
    --background: #f8fafc;
    --text: #1e293b;
    --border: #e2e8f0;
    --card-bg: #ffffff;
    --success: #10b981;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

body {
    background-color: var(--background);
    color: var(--text);
    line-height: 1.6;
    padding: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

h1 {
    text-align: center;
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: 2rem;
}

.calculator {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    padding: 30px;
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text);
}

input[type="number"],
select {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 16px;
    transition: border-color 0.3s;
}

input[type="number"]:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.btn-calculate {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    width: 100%;
    transition: background-color 0.3s;
}

.btn-calculate:hover {
    background-color: var(--primary-light);
}

.results {
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--border);
}

.results h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.5rem;
}

.result-item {
    display: flex;
    justify-content: space-between;
    margin-bottom: 12px;
    padding: 12px;
    background-color: var(--background);
    border-radius: 6px;
}

.result-item span:first-child {
    font-weight: 500;
}

.hidden {
    display: none;
}

/* Responsive Design */
@media (max-width: 768px) {
    .calculator {
        padding: 20px;
    }

    h1 {
        font-size: 1.75rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 10px;
    }

    .calculator {
        padding: 15px;
    }

    h1 {
        font-size: 1.5rem;
    }

    .result-item {
        flex-direction: column;
    }

    .result-item span:first-child {
        margin-bottom: 4px;
    }
}