body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #1e40af;
    --primary-dark: #1e3a8a;
    --primary-light: #3b82f6;
    --secondary: #f59e0b;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --border: #e5e7eb;
    --bg-light: #f9fafb;
    --success: #10b981;
    --error: #ef4444;
}

html, body {
    height: 100%;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    background: white;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    background: white;
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
}

.logo a {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--primary);
    font-weight: 700;
    font-size: 20px;
}

.logo-text {
    line-height: 1.2;
    display: flex;
    flex-direction: column;
}

.logo-sub {
    font-size: 12px;
    letter-spacing: 1px;
    font-weight: 600;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--primary);
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 5px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    border-radius: 2px;
}

/* Hero */
.hero {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 80px 20px;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    margin-bottom: 15px;
}

.hero p {
    font-size: 20px;
    margin-bottom: 30px;
    opacity: 0.95;
}

.search-box {
    display: flex;
    max-width: 500px;
    margin: 0 auto;
    gap: 10px;
}

.search-box input {
    flex: 1;
    padding: 12px 16px;
    border: none;
    border-radius: 6px;
    font-size: 16px;
}

.search-box button {
    padding: 12px 32px;
    background: var(--secondary);
    color: white;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: background 0.3s;
}

.search-box button:hover {
    background: #d97706;
}

/* Main Content */
main {
    padding: 60px 20px;
}

section {
    margin-bottom: 80px;
}

section h2 {
    font-size: 36px;
    margin-bottom: 40px;
    text-align: center;
}

/* Calculator Grid */
.calculator-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.calc-card {
    background: white;
    border: 2px solid var(--border);
    border-radius: 8px;
    padding: 25px;
    text-decoration: none;
    color: inherit;
    transition: all 0.3s;
    cursor: pointer;
}

.calc-card:hover {
    border-color: var(--primary);
    box-shadow: 0 4px 12px rgba(30, 64, 175, 0.1);
    transform: translateY(-2px);
}

.calc-card h3 {
    color: var(--primary);
    margin-bottom: 10px;
}

.calc-card p {
    color: var(--text-light);
    font-size: 14px;
}

/* Categories */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.category {
    padding: 20px;
}

.category h3 {
    color: var(--primary);
    margin-bottom: 15px;
}

.category ul {
    list-style: none;
}

.category li {
    margin-bottom: 10px;
}

.category a {
    color: var(--text-light);
    text-decoration: none;
    transition: color 0.3s;
}

.category a:hover {
    color: var(--primary);
}

/* Footer */
footer {
    background: var(--text-dark);
    color: white;
    padding: 60px 20px 20px;
    margin-top: 80px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h4 {
    margin-bottom: 15px;
}

.footer-section ul {
    list-style: none;
}

.footer-section li {
    margin-bottom: 10px;
}

.footer-section a {
    color: #d1d5db;
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: #9ca3af;
}

/* Calculator Page Styles */
.calculator-container {
    max-width: 800px;
    margin: 40px auto;
    background: var(--bg-light);
    padding: 40px;
    border-radius: 12px;
}

.calculator-header {
    margin-bottom: 40px;
}

.calculator-header h1 {
    font-size: 36px;
    margin-bottom: 10px;
}

.calculator-header p {
    color: var(--text-light);
    font-size: 16px;
}

.calculator-form {
    background: white;
    padding: 30px;
    border-radius: 8px;
    border: 1px solid var(--border);
    margin-bottom: 30px;
}

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

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-dark);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 16px;
    font-family: inherit;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(30, 64, 175, 0.1);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

button.calculate-btn {
    width: 100%;
    padding: 14px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.3s;
}

button.calculate-btn:hover {
    background: var(--primary-dark);
}

.result-box {
    background: #ecfdf5;
    border: 2px solid var(--success);
    padding: 25px;
    border-radius: 8px;
    margin-bottom: 30px;
    display: none;
}

.result-box.show {
    display: block;
}

.result-box h3 {
    color: var(--success);
    margin-bottom: 10px;
}

.result-value {
    font-size: 32px;
    font-weight: 700;
    color: var(--text-dark);
    margin: 15px 0;
}

.result-details {
    color: var(--text-light);
    font-size: 14px;
    line-height: 1.8;
}

.explanation {
    background: white;
    padding: 25px;
    border-radius: 8px;
    border-left: 4px solid var(--primary);
    margin-bottom: 30px;
}

.explanation h3 {
    color: var(--primary);
    margin-bottom: 15px;
}

.explanation p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 10px;
}

.explanation p:last-child {
    margin-bottom: 0;
}

.related-calculators {
    background: white;
    padding: 25px;
    border-radius: 8px;
    border: 1px solid var(--border);
}

.related-calculators h3 {
    color: var(--text-dark);
    margin-bottom: 15px;
}

.related-list {
    list-style: none;
}

.related-list li {
    margin-bottom: 10px;
}

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

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

/* Ad Placeholder */
.ad-placeholder {
    background: var(--bg-light);
    border: 2px dashed var(--border);
    padding: 20px;
    text-align: center;
    color: var(--text-light);
    font-size: 12px;
    margin: 20px 0;
    border-radius: 6px;
}

/* FAQ */
.faq {
    background: white;
    border-radius: 8px;
    border: 1px solid var(--border);
    padding: 25px;
    margin-top: 30px;
}

.faq h3 {
    color: var(--text-dark);
    margin-bottom: 20px;
}

.faq-item {
    margin-bottom: 15px;
    border-bottom: 1px solid var(--border);
    padding-bottom: 15px;
}

.faq-item:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.faq-question {
    font-weight: 600;
    color: var(--text-dark);
    cursor: pointer;
    user-select: none;
}

.faq-answer {
    color: var(--text-light);
    margin-top: 8px;
    display: none;
}

.faq-answer.show {
    display: block;
}

/* Responsive */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hamburger {
        display: flex;
    }

    .hero h1 {
        font-size: 32px;
    }

    .hero p {
        font-size: 16px;
    }

    .search-box {
        flex-direction: column;
    }

    .calculator-grid {
        grid-template-columns: 1fr;
    }

    .category-grid {
        grid-template-columns: 1fr;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .calculator-container {
        padding: 20px;
    }

    .result-value {
        font-size: 24px;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 24px;
    }

    section h2 {
        font-size: 24px;
    }

    .calculator-form {
        padding: 20px;
    }
}