* {
    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: 1200px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    overflow: hidden;
}

header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px;
    text-align: center;
}

h1 {
    font-size: 2.5em;
    margin-bottom: 10px;
}

.tabs {
    display: flex;
    flex-wrap: wrap;
    background: #f5f5f5;
    padding: 10px;
    gap: 10px;
}

.tab {
    padding: 12px 20px;
    background: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
    font-size: 14px;
    font-weight: 500;
}

.tab:hover {
    background: #667eea;
    color: white;
    transform: translateY(-2px);
}

.tab.active {
    background: #667eea;
    color: white;
}

.content {
    padding: 30px;
}

.calculator {
    display: none;
}

.calculator.active {
    display: block;
}

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

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

input, select {
    width: 100%;
    padding: 12px;
    border: 2px solid #e0e0e0;
    border-radius: 8px;
    font-size: 16px;
    transition: border 0.3s;
}

input:focus, select:focus {
    outline: none;
    border-color: #667eea;
}

button.calc-btn {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 15px 40px;
    border: none;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    margin-top: 10px;
}

button.calc-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
}

.result {
    margin-top: 30px;
    padding: 20px;
    background: #f0f4ff;
    border-radius: 12px;
    border-left: 5px solid #667eea;
}

.result h3 {
    color: #667eea;
    margin-bottom: 15px;
}

.result p {
    margin: 10px 0;
    font-size: 16px;
    line-height: 1.6;
}

.formula-display {
    background: #fff;
    padding: 15px;
    border-radius: 8px;
    margin: 10px 0;
    font-family: 'Courier New', monospace;
    border: 1px solid #e0e0e0;
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 768px) {
    .grid-2 {
        grid-template-columns: 1fr;
    }
    
    h1 {
        font-size: 1.8em;
    }
    
    .tabs {
        justify-content: center;
    }
}