:root {
    --primary-color: #2196F3;
    --primary-dark: #1976D2;
    --text-color: #333;
    --background-light: #f5f5f5;
    --spacing-unit: 20px;
}

body {
    font-family: 'Roboto', Arial, sans-serif;
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    background-color: #f9f9f9;
    color: var(--text-color);
    line-height: 1.6;
}

.header {
    text-align: center;
    padding: 40px 0;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
    border-radius: 10px;
    margin-bottom: 30px;
}

.header h1 {
    margin: 0;
    font-size: 2.5em;
}

.header p {
    margin: 10px 0 0;
    font-size: 1.2em;
    opacity: 0.9;
}

.calculator-section {
    background: white;
    margin-bottom: var(--spacing-unit);
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.calculator-section:hover {
    transform: translateY(-2px);
}

.calculator-section h2 {
    color: var(--primary-color);
    margin-top: 0;
    border-bottom: 2px solid var(--background-light);
    padding-bottom: 10px;
}

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

label {
    display: inline-block;
    width: 200px;
    font-weight: 500;
}

input {
    padding: 8px 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    width: 200px;
    transition: border-color 0.3s;
}

input:focus {
    outline: none;
    border-color: var(--primary-color);
}

button {
    padding: 10px 25px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s;
    font-weight: 500;
}

button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-1px);
}

.result {
    margin-top: 15px;
    padding: 15px;
    background-color: var(--background-light);
    border-radius: 6px;
    font-weight: 500;
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.resource-card {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.resource-card:hover {
    transform: translateY(-3px);
}

.resource-card h3 {
    color: var(--primary-color);
    margin-top: 0;
}

.resource-card ul {
    list-style-type: none;
    padding: 0;
}

.resource-card li {
    margin-bottom: 10px;
}

.resource-card a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s;
}

.resource-card a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.nav-tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 30px;
    border-bottom: 2px solid var(--background-light);
    padding-bottom: 10px;
}

.nav-tab {
    padding: 10px 20px;
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-weight: 500;
    transition: all 0.3s;
}

.nav-tab.active {
    color: var(--primary-color);
    border-bottom: 2px solid var(--primary-color);
}

.tab-content {
    display: none;
}

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

@media (max-width: 768px) {
    body {
        padding: 10px;
    }
    
    label {
        width: 100%;
        margin-bottom: 5px;
    }
    
    input {
        width: 100%;
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
}