* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 600px;
}

.calculator-box {
    background: white;
    border-radius: 12px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.2);
    padding: 40px;
}

h1 {
    color: #333;
    text-align: center;
    margin-bottom: 10px;
    font-size: 2.5em;
}

.subtitle {
    text-align: center;
    color: #666;
    margin-bottom: 30px;
    font-size: 1.1em;
}

.form-group {
    margin-bottom: 25px;
}

label {
    display: block;
    margin-bottom: 8px;
    color: #333;
    font-weight: 600;
    font-size: 1.05em;
}

input[type="date"] {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 1em;
    transition: border-color 0.3s ease;
}

input[type="date"]:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.btn-calculate {
    width: 100%;
    padding: 14px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 1.1em;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-calculate:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(102, 126, 234, 0.4);
}

.btn-calculate:active {
    transform: translateY(0);
}

.results {
    margin-top: 40px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.results.hidden {
    display: none;
}

.result-item {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 8px;
    border-left: 4px solid #667eea;
}

.result-item h3 {
    color: #333;
    font-size: 0.95em;
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.result-value {
    color: #667eea;
    font-size: 1.3em;
    font-weight: 700;
}

.error {
    margin-top: 20px;
    padding: 15px;
    background-color: #fee;
    color: #c33;
    border-radius: 8px;
    border-left: 4px solid #c33;
    font-weight: 500;
}

.error.hidden {
    display: none;
}

@media (max-width: 600px) {
    .calculator-box {
        padding: 25px;
    }
    
    h1 {
        font-size: 2em;
    }
    
    .results {
        grid-template-columns: 1fr;
    }
}