:root {
    --primary-color: #4a6fa5;
    --secondary-color: #6c8dbc;
    --background-color: #f5f7fa;
    --card-color: #ffffff;
    --text-color: #333333;
    --border-radius: 8px;
    --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 20px;
}

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

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.description {
    color: #666;
    margin-bottom: 30px;
}

.calculator-container {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    justify-content: center;
}

.calculator {
    background-color: var(--card-color);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    padding: 20px;
    flex: 1 1 350px;
    margin-bottom: 20px;
}

h2 {
    color: var(--primary-color);
    margin-top: 0;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
}

.input-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
}

input[type="number"] {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
}

.checkbox-group {
    margin-bottom: 15px;
}

.checkbox-label {
    display: flex;
    align-items: center;
    cursor: pointer;
}

input[type="checkbox"] {
    margin-right: 8px;
}

button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 15px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
    transition: background-color 0.3s;
    width: 100%;
}

button:hover {
    background-color: var(--secondary-color);
}

.result-container {
    margin-top: 20px;
    padding: 15px;
    background-color: #f8f9fa;
    border-radius: 4px;
}

.result-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}

.result-label {
    font-weight: 500;
}

.result-value {
    font-family: monospace;
    font-size: 16px;
}

.formula {
    font-style: italic;
    color: #666;
    margin-top: 15px;
    font-size: 14px;
}

footer {
    text-align: center;
    margin-top: 40px;
    color: #666;
    font-size: 14px;
}

@media (max-width: 768px) {
    .calculator {
        flex: 1 1 100%;
    }
}

.language-selector {
    position: absolute;
    top: 20px;
    right: 20px;
}

.language-selector select {
    padding: 5px 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
    background-color: white;
    font-size: 14px;
    cursor: pointer;
}

.language-selector select:hover {
    border-color: #999;
}