* {
    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;
    padding: 20px;
}

.container {
    max-width: 500px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #2c3e50, #34495e);
    color: white;
    padding: 20px;
    text-align: center;
}

header h1 {
    font-size: 1.5em;
    margin-bottom: 5px;
}

.developer {
    font-size: 0.9em;
    opacity: 0.8;
}

.tabs {
    display: flex;
    background: #f8f9fa;
    border-bottom: 1px solid #dee2e6;
}

.tab-button {
    flex: 1;
    padding: 15px 10px;
    border: none;
    background: transparent;
    cursor: pointer;
    font-size: 0.8em;
    font-weight: 600;
    color: #6c757d;
    transition: all 0.3s ease;
}

.tab-button.active {
    background: white;
    color: #007bff;
    border-bottom: 3px solid #007bff;
}

.tab-content {
    display: none;
    padding: 0;
}

.tab-content.active {
    display: block;
}

.calculator-card {
    padding: 20px;
}

.calculator-card h3 {
    color: #2c3e50;
    margin-bottom: 20px;
    text-align: center;
    font-size: 1.3em;
}

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

label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: #495057;
}

input, select {
    width: 100%;
    padding: 12px 15px;
    border: 2px solid #e9ecef;
    border-radius: 10px;
    font-size: 16px;
    transition: border-color 0.3s ease;
}

input:focus, select:focus {
    outline: none;
    border-color: #007bff;
}

.calculate-btn {
    width: 100%;
    padding: 15px;
    background: linear-gradient(135deg, #007bff, #0056b3);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.2s ease;
    margin-top: 10px;
}

.calculate-btn:active {
    transform: scale(0.98);
}

.result-box {
    margin-top: 20px;
    padding: 20px;
    background: #f8f9fa;
    border-radius: 10px;
    border-left: 5px solid #007bff;
}

.result-box h4 {
    color: #2c3e50;
    margin-bottom: 15px;
    text-align: center;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 8px 0;
    border-bottom: 1px solid #dee2e6;
}

.result-item:last-child {
    border-bottom: none;
}

.result-item span:first-child {
    font-weight: 600;
    color: #495057;
}

.result-item span:last-child {
    font-weight: 700;
    color: #007bff;
}

footer {
    padding: 15px 20px;
    background: #f8f9fa;
    text-align: center;
    font-size: 0.8em;
    color: #6c757d;
    border-top: 1px solid #dee2e6;
}

@media (max-width: 480px) {
    body {
        padding: 10px;
    }
    
    .container {
        border-radius: 15px;
    }
    
    header h1 {
        font-size: 1.3em;
    }
    
    .tab-button {
        font-size: 0.7em;
        padding: 12px 5px;
    }
    
    .calculator-card {
        padding: 15px;
    }
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.result-box {
    animation: fadeIn 0.5s ease;
}