:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a2e;
    --bg-card-hover: #222240;
    --bg-glass: rgba(26, 26, 46, 0.7);
    --bg-input: #16162a;
    --text-primary: #e8e8f0;
    --text-secondary: #9495b7;
    --text-muted: #6b6c8a;
    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-glow: rgba(99, 102, 241, 0.15);
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6);
    --success: #22c55e;
    --warning: #f59e0b;
    --error: #ef4444;
    --border-color: rgba(99, 102, 241, 0.15);
    --border-subtle: rgba(255, 255, 255, 0.06);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 40px rgba(0,0,0,0.4);
    --shadow-glow: 0 0 30px rgba(99, 102, 241, 0.1);
    --font-primary: 'Space Grotesk', sans-serif;
    --font-secondary: 'Inter', sans-serif;
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-secondary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.7;
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

a {
    color: var(--accent-primary);
    text-decoration: none;
    transition: color var(--transition);
}

a:hover {
    color: var(--accent-secondary);
}

h1, h2, h3, h4 {
    font-family: var(--font-primary);
    font-weight: 600;
    line-height: 1.3;
}

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(10, 10, 15, 0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-subtle);
    padding: 0 0;
    transition: background var(--transition);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: var(--font-primary);
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.logo:hover {
    color: var(--text-primary);
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    transition: color var(--transition);
    position: relative;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-gradient);
    border-radius: 1px;
    transition: width var(--transition);
}

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

.nav-links a:hover::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 22px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 1px;
    transition: var(--transition);
}

/* Hero */
.hero {
    padding: 140px 0 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: 50%;
    transform: translateX(-50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.08) 0%, transparent 70%);
    pointer-events: none;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 16px;
    background: var(--accent-glow);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--accent-primary);
    margin-bottom: 24px;
}

.hero h1 {
    font-size: clamp(2.2rem, 5vw, 3.5rem);
    font-weight: 700;
    margin-bottom: 20px;
    background: linear-gradient(135deg, var(--text-primary), var(--accent-primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero p {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.8;
}

/* Search Bar */
.search-bar {
    max-width: 520px;
    margin: 32px auto 0;
    position: relative;
}

.search-bar input[type="text"] {
    width: 100%;
    padding: 14px 20px 14px 56px;
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: 100px;
    color: var(--text-primary);
    font-family: var(--font-secondary);
    font-size: 0.95rem;
    outline: none;
    transition: all var(--transition);
}

.search-bar input:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-bar input::placeholder {
    color: var(--text-muted);
}

.search-bar .search-icon {
    position: absolute;
    left: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    pointer-events: none;
    width: 18px;
    height: 18px;
    flex-shrink: 0;
    opacity: 0.7;
}

/* Filter Tabs */
.filter-bar {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 24px;
}

.filter-btn {
    padding: 8px 20px;
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: 100px;
    color: var(--text-secondary);
    font-family: var(--font-secondary);
    font-size: 0.82rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    letter-spacing: 0.02em;
}

.filter-btn:hover {
    border-color: var(--border-color);
    color: var(--text-primary);
}

.filter-btn.active {
    background: var(--accent-glow);
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    font-weight: 600;
}

/* No Results */
.no-results {
    display: none;
    text-align: center;
    padding: 60px 20px;
    color: var(--text-muted);
    font-size: 1rem;
}

.no-results.visible {
    display: block;
}

.calc-card.hidden {
    display: none;
}

.section.hidden {
    display: none;
}

/* Section */
.section {
    padding: 60px 0;
}

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

.section-header h2 {
    font-size: 1.5rem;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.section-header h2 .icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: var(--accent-glow);
    border-radius: var(--radius-sm);
    color: var(--accent-primary);
}

.section-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Calculator Grid */
.calc-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.calc-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 28px;
    transition: all var(--transition);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.calc-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent-gradient);
    opacity: 0;
    transition: opacity var(--transition);
}

.calc-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-color);
    transform: translateY(-4px);
    box-shadow: var(--shadow-glow);
}

.calc-card:hover::before {
    opacity: 1;
}

.calc-card-icon {
    width: 44px;
    height: 44px;
    background: var(--accent-glow);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--accent-primary);
}

.calc-card h3 {
    font-size: 1.05rem;
    font-weight: 600;
}

.calc-card h3 a {
    color: var(--text-primary);
}

.calc-card h3 a:hover {
    color: var(--accent-primary);
}

.calc-card p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.6;
    flex-grow: 1;
}

.calc-card .card-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--accent-primary);
    margin-top: 4px;
}

.calc-card .card-link svg {
    transition: transform var(--transition);
}

.calc-card:hover .card-link svg {
    transform: translateX(4px);
}

/* Calculator Page Layout */
.calc-page {
    padding: 100px 0 60px;
}

.calc-page .container {
    max-width: 800px;
}

.calc-breadcrumb {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 24px;
}

.calc-breadcrumb a {
    color: var(--text-muted);
}

.calc-breadcrumb a:hover {
    color: var(--accent-primary);
}

.calc-breadcrumb span {
    color: var(--text-secondary);
}

.calc-page h1 {
    font-size: clamp(1.8rem, 4vw, 2.4rem);
    margin-bottom: 12px;
}

.calc-intro {
    color: var(--text-secondary);
    font-size: 1rem;
    margin-bottom: 36px;
    line-height: 1.8;
}

/* Calculator Box */
.calc-box {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-xl);
    padding: 36px;
    margin-bottom: 36px;
    position: relative;
}

.calc-box::before {
    content: '';
    position: absolute;
    inset: -1px;
    border-radius: var(--radius-xl);
    padding: 1px;
    background: linear-gradient(135deg, rgba(99,102,241,0.2), transparent, rgba(139,92,246,0.2));
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
    pointer-events: none;
}

/* Form Elements */
.form-group {
    margin-bottom: 20px;
    position: relative;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}

label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 8px;
    letter-spacing: 0.02em;
}

input[type="number"],
input[type="text"],
input[type="email"],
input[type="date"],
select {
    width: 100%;
    padding: 12px 16px;
    background: var(--bg-input);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: var(--font-secondary);
    font-size: 0.95rem;
    transition: all var(--transition);
    outline: none;
}

input:focus,
select:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

input::placeholder {
    color: var(--text-muted);
}

select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%236b6c8a' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 14px center;
    padding-right: 36px;
}

.radio-group {
    display: flex;
    gap: 12px;
}

.radio-option {
    flex: 1;
}

.radio-option input {
    display: none;
}

.radio-option label {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 10px 16px;
    background: var(--bg-input);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.9rem;
    color: var(--text-secondary);
    transition: all var(--transition);
    margin-bottom: 0;
}

.radio-option input:checked + label {
    background: var(--accent-glow);
    border-color: var(--accent-primary);
    color: var(--accent-primary);
    font-weight: 500;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 13px 28px;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    border-radius: var(--radius-md);
    font-family: var(--font-primary);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition);
    width: 100%;
    letter-spacing: 0.02em;
}

.btn:hover {
    opacity: 0.9;
    transform: translateY(-1px);
    box-shadow: 0 4px 20px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
    background: var(--bg-input);
    border: 1px solid var(--border-subtle);
    color: var(--text-secondary);
}

.btn-secondary:hover {
    border-color: var(--border-color);
    color: var(--text-primary);
    box-shadow: none;
}

.btn-row {
    display: flex;
    gap: 12px;
}

.btn-row .btn {
    flex: 2;
}

.btn-row .btn-secondary {
    flex: 1;
}

/* Result Box */
.result-box {
    display: none;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.08), rgba(139, 92, 246, 0.05));
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px;
    margin-top: 24px;
    text-align: center;
    animation: fadeInUp 0.4s ease;
}

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

.result-label {
    font-size: 0.85rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.result-value {
    font-family: var(--font-primary);
    font-size: 2.2rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 8px;
}

.result-detail {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.result-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    margin-top: 16px;
}

.result-item {
    background: rgba(0,0,0,0.2);
    padding: 16px;
    border-radius: var(--radius-md);
}

.result-item .result-label {
    font-size: 0.75rem;
    margin-bottom: 4px;
}

.result-item .result-value {
    font-size: 1.3rem;
}

.error-msg {
    color: var(--error);
    font-size: 0.8rem;
    margin-top: 4px;
    display: none;
}

.disclaimer-note {
    font-size: 0.8rem;
    color: var(--text-muted);
    text-align: center;
    margin-top: 16px;
    font-style: italic;
}

/* Info Section */
.info-section {
    margin-top: 48px;
}

.info-section h2 {
    font-size: 1.3rem;
    margin-bottom: 16px;
}

.info-section p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 16px;
    line-height: 1.8;
}

/* FAQ */
.faq-section {
    margin-top: 48px;
}

.faq-section h2 {
    font-size: 1.3rem;
    margin-bottom: 20px;
}

.faq-item {
    border-bottom: 1px solid var(--border-subtle);
    padding: 16px 0;
}

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

.faq-q {
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 8px;
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
}

.faq-q::after {
    content: '+';
    font-size: 1.2rem;
    color: var(--accent-primary);
    font-weight: 400;
    flex-shrink: 0;
    transition: transform var(--transition);
}

.faq-item.open .faq-q::after {
    content: '−';
}

.faq-a {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.7;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.faq-item.open .faq-a {
    max-height: 500px;
}

/* Related Calculators */
.related-section {
    margin-top: 48px;
}

.related-section h2 {
    font-size: 1.3rem;
    margin-bottom: 20px;
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 14px;
}

.related-card {
    background: var(--bg-card);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 18px;
    transition: all var(--transition);
}

.related-card:hover {
    border-color: var(--border-color);
    transform: translateY(-2px);
}

.related-card a {
    color: var(--text-primary);
    font-weight: 500;
    font-size: 0.9rem;
}

.related-card p {
    color: var(--text-muted);
    font-size: 0.8rem;
    margin-top: 4px;
}

/* Footer */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-subtle);
    padding: 60px 0 30px;
    margin-top: 80px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-col h3 {
    font-size: 1.15rem;
    margin-bottom: 12px;
}

.footer-col h4 {
    font-size: 0.9rem;
    color: var(--text-primary);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-col p {
    color: var(--text-muted);
    font-size: 0.85rem;
    line-height: 1.7;
}

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

.footer-col ul li {
    margin-bottom: 8px;
}

.footer-col ul a {
    color: var(--text-muted);
    font-size: 0.85rem;
    transition: color var(--transition);
}

.footer-col ul a:hover {
    color: var(--accent-primary);
}

.footer-bottom {
    border-top: 1px solid var(--border-subtle);
    padding-top: 24px;
    text-align: center;
}

.footer-bottom p {
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* Back to top */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 44px;
    height: 44px;
    background: var(--accent-gradient);
    border: none;
    border-radius: 50%;
    color: #fff;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition);
    z-index: 50;
    box-shadow: var(--shadow-md);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-3px);
}

/* Utility page */
.page-content {
    padding: 100px 0 60px;
}

.page-content .container {
    max-width: 800px;
}

.page-content h1 {
    font-size: 2rem;
    margin-bottom: 24px;
}

.page-content h2 {
    font-size: 1.3rem;
    margin-top: 32px;
    margin-bottom: 12px;
}

.page-content p, .page-content li {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.8;
    margin-bottom: 12px;
}

.page-content ul {
    padding-left: 24px;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(16px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeInUp 0.5s ease;
}

/* Mobile responsive */
@media (max-width: 768px) {
    .nav-toggle {
        display: flex;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(10, 10, 15, 0.97);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 20px 24px;
        gap: 0;
        border-bottom: 1px solid var(--border-subtle);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links li {
        padding: 12px 0;
        border-bottom: 1px solid var(--border-subtle);
    }

    .nav-links li:last-child {
        border-bottom: none;
    }

    .hero {
        padding: 110px 0 60px;
    }

    .calc-box {
        padding: 24px;
    }

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

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

    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 30px;
    }

    .filter-bar {
        gap: 6px;
    }

    .filter-btn {
        padding: 7px 14px;
        font-size: 0.78rem;
    }

    .btn-row {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .footer-grid {
        grid-template-columns: 1fr;
    }

    .radio-group {
        flex-direction: column;
    }

    .result-value {
        font-size: 1.8rem;
    }
}