/* ===================================
   CSS Variables & Theme System
   =================================== */
:root {
    /* Light Mode (Default) */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-card: #ffffff;
    --text-primary: #333333;
    --text-secondary: #666666;
    --text-muted: #999999;
    --border-color: #e0e0e0;
    --border-light: #f0f0f0;
    
    /* Accent Colors */
    --accent-blue: #3b82f6;
    --accent-blue-hover: #2563eb;
    --accent-orange: #f59e0b;
    --accent-orange-light: #fef3c7;
    --accent-green: #10b981;
    --accent-red: #ef4444;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #121212;
    --bg-card: #242424;
    --text-primary: #e0e0e0;
    --text-secondary: #a0a0a0;
    --text-muted: #707070;
    --border-color: #333333;
    --border-light: #2a2a2a;
    
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.4);
}

/* ===================================
   Reset & Base Styles
   =================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: var(--transition);
    min-height: 100vh;
}

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

/* ===================================
   Header
   =================================== */
.header {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: var(--transition);
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.logo i {
    color: var(--accent-blue);
    font-size: 1.5rem;
}

.theme-toggle {
    width: 44px;
    height: 44px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-card);
    color: var(--text-primary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    transition: var(--transition);
}

.theme-toggle:hover {
    background-color: var(--bg-secondary);
    border-color: var(--accent-blue);
    color: var(--accent-blue);
}

/* ===================================
   Main Content
   =================================== */
.main-content {
    padding-bottom: 60px;
}

/* ===================================
   Hero Calculator (발표시간 계산기)
   =================================== */
.hero-calculator {
    background: linear-gradient(135deg, var(--accent-blue) 0%, #1d4ed8 100%);
    padding: 60px 0;
    margin-bottom: 40px;
}

[data-theme="dark"] .hero-calculator {
    background: linear-gradient(135deg, #1e3a5f 0%, #0f172a 100%);
}

.hero-title {
    text-align: center;
    color: #ffffff;
    margin-bottom: 40px;
}

.hero-title h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
}

.hero-title p {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* ===================================
   Calculator Card
   =================================== */
.calculator-card {
    background-color: var(--bg-card);
    border-radius: 20px;
    padding: 32px;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.main-calculator {
    max-width: 700px;
    margin: 0 auto;
}

/* Input Tabs */
.input-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 24px;
    background-color: var(--bg-secondary);
    padding: 6px;
    border-radius: 12px;
}

.tab-btn {
    flex: 1;
    padding: 12px 16px;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

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

.tab-btn.active {
    background-color: var(--bg-card);
    color: var(--accent-blue);
    box-shadow: var(--shadow-sm);
}

/* Tab Content */
.tab-content {
    display: none;
}

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

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

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 14px 16px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
    font-family: inherit;
    transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.15);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.char-count {
    margin-top: 8px;
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* Speed Setting */
.speed-setting {
    margin: 24px 0;
    padding-top: 24px;
    border-top: 1px solid var(--border-light);
}

.speed-setting > label {
    display: block;
    font-weight: 500;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.speed-options {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.speed-btn {
    padding: 14px 12px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: 12px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: var(--transition);
    text-align: center;
}

.speed-btn small {
    display: block;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 4px;
    font-weight: 400;
}

.speed-btn:hover {
    border-color: var(--accent-blue);
    color: var(--accent-blue);
}

.speed-btn.active {
    background-color: var(--accent-blue);
    border-color: var(--accent-blue);
    color: #ffffff;
}

.speed-btn.active small {
    color: rgba(255, 255, 255, 0.8);
}

.custom-speed {
    margin-top: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.custom-speed input {
    width: 120px;
    padding: 10px 14px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
}

.custom-speed span {
    color: var(--text-secondary);
}

/* Calculate Button */
.calculate-btn {
    width: 100%;
    padding: 16px 24px;
    background: linear-gradient(135deg, var(--accent-blue) 0%, #2563eb 100%);
    color: #ffffff;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    margin-top: 24px;
}

.calculate-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.35);
}

.calculate-btn:active {
    transform: translateY(0);
}

/* Result Box */
.result-box {
    margin-top: 32px;
    padding: 28px;
    background-color: var(--bg-secondary);
    border-radius: 16px;
    border: 1px solid var(--border-light);
}

.result-main {
    text-align: center;
    padding-bottom: 24px;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 24px;
}

.result-label {
    display: block;
    font-size: 0.95rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.result-value {
    display: block;
    font-size: 3rem;
    font-weight: 700;
    color: var(--accent-orange);
}

.result-details {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin-bottom: 24px;
}

.result-item {
    text-align: center;
    padding: 16px;
    background-color: var(--bg-card);
    border-radius: 12px;
}

.result-item i {
    font-size: 1.3rem;
    color: var(--accent-blue);
    margin-bottom: 8px;
    display: block;
}

.result-item span {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.result-item strong {
    font-size: 1.1rem;
    color: var(--text-primary);
}

.result-tips {
    background-color: var(--accent-orange-light);
    padding: 20px;
    border-radius: 12px;
}

[data-theme="dark"] .result-tips {
    background-color: rgba(245, 158, 11, 0.15);
}

.result-tips h4 {
    color: var(--accent-orange);
    font-size: 1rem;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.result-tips ul {
    list-style: none;
    padding-left: 0;
}

.result-tips li {
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.result-tips li::before {
    content: "•";
    color: var(--accent-orange);
    position: absolute;
    left: 0;
    font-weight: bold;
}

/* ===================================
   Other Calculators Section
   =================================== */
.other-calculators {
    padding: 20px 0;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 32px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.section-title i {
    color: var(--accent-blue);
}

.calculator-grid {
    display: grid;
    gap: 32px;
}

.calc-category h3 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.calc-category h3 i {
    color: var(--accent-blue);
    width: 24px;
}

.calc-cards {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 12px;
}

.calc-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    padding: 20px 16px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
}

.calc-card:hover {
    border-color: var(--accent-blue);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.calc-card i {
    font-size: 1.8rem;
    color: var(--accent-blue);
    margin-bottom: 10px;
    display: block;
}

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

/* ===================================
   Flat Grid Calculator List
   =================================== */
.calc-grid-flat {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    gap: 12px;
}

.calc-card-flat {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 20px 12px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 14px;
    text-decoration: none;
    transition: var(--transition);
}

.calc-card-flat:hover {
    border-color: var(--accent-blue);
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    background-color: var(--accent-blue);
}

.calc-card-flat:hover i,
.calc-card-flat:hover span {
    color: #ffffff;
}

.calc-card-flat i {
    font-size: 1.75rem;
    color: var(--accent-blue);
    transition: var(--transition);
}

.calc-card-flat span {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-primary);
    text-align: center;
    transition: var(--transition);
}

@media (max-width: 900px) {
    .calc-grid-flat {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 600px) {
    .calc-grid-flat {
        grid-template-columns: repeat(3, 1fr);
        gap: 10px;
    }
    
    .calc-card-flat {
        padding: 16px 8px;
    }
    
    .calc-card-flat i {
        font-size: 1.5rem;
    }
    
    .calc-card-flat span {
        font-size: 0.75rem;
    }
}

@media (max-width: 400px) {
    .calc-grid-flat {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* ===================================
   Modal
   =================================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    padding: 20px;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background-color: var(--bg-card);
    border-radius: 20px;
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    transform: scale(0.9) translateY(20px);
    transition: var(--transition);
}

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    background-color: var(--bg-card);
    z-index: 10;
}

.modal-header h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.modal-close {
    width: 36px;
    height: 36px;
    border-radius: 10px;
    border: none;
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.modal-close:hover {
    background-color: var(--accent-red);
    color: #ffffff;
}

.modal-body {
    padding: 24px;
}

/* Modal Calculator Styles */
.modal-body .form-group {
    margin-bottom: 16px;
}

.modal-body .calculate-btn {
    margin-top: 20px;
}

.modal-result {
    margin-top: 24px;
    padding: 20px;
    background-color: var(--bg-secondary);
    border-radius: 12px;
    text-align: center;
}

.modal-result .result-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 8px;
}

.modal-result .result-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-orange);
}

.modal-result-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
    margin-top: 16px;
}

.modal-result-item {
    padding: 12px;
    background-color: var(--bg-card);
    border-radius: 10px;
    text-align: center;
}

.modal-result-item span {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-bottom: 4px;
}

.modal-result-item strong {
    font-size: 1rem;
    color: var(--text-primary);
}

/* ===================================
   Footer
   =================================== */
.footer {
    background-color: var(--bg-primary);
    border-top: 1px solid var(--border-color);
    padding: 24px 0;
    text-align: center;
}

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

.footer-links {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--accent-blue);
}

/* ===================================
   Legal Pages (Privacy, Terms)
   =================================== */
.legal-content {
    padding: 40px 0 60px;
}

.legal-article {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--bg-card);
    padding: 40px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.legal-article .last-updated {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 32px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-color);
}

.legal-article h2 {
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
    margin-top: 32px;
    margin-bottom: 12px;
}

.legal-article h2:first-of-type {
    margin-top: 0;
}

.legal-article p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 12px;
}

.legal-article ul {
    margin: 12px 0 20px 24px;
}

.legal-article li {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 8px;
}

.legal-article a {
    color: var(--accent-blue);
    text-decoration: none;
}

.legal-article a:hover {
    text-decoration: underline;
}

/* ===================================
   About Page
   =================================== */
.about-content {
    padding: 40px 0 60px;
}

.about-article {
    max-width: 900px;
    margin: 0 auto;
}

.about-section {
    background-color: var(--bg-card);
    padding: 32px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

.about-section h2 {
    color: var(--text-primary);
    font-size: 1.35rem;
    font-weight: 600;
    margin-bottom: 16px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.about-section h2 i {
    color: var(--accent-blue);
}

.about-section p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 16px;
}

.about-section ul {
    margin: 12px 0 0 24px;
}

.about-section li {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 8px;
}

.about-section a {
    color: var(--accent-blue);
    text-decoration: none;
}

.about-section a:hover {
    text-decoration: underline;
}

.service-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

.service-item {
    background-color: var(--bg-secondary);
    padding: 20px;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.service-item h3 {
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.service-item h3 i {
    color: var(--accent-blue);
    font-size: 0.9rem;
}

.service-item p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin: 0;
}

/* ===================================
   Contact Page
   =================================== */
.contact-content {
    padding: 40px 0 60px;
}

.contact-wrapper {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 32px;
    max-width: 1000px;
    margin: 0 auto 40px;
}

.contact-info,
.contact-form-section {
    background-color: var(--bg-card);
    padding: 32px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.contact-info h2,
.contact-form-section h2 {
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 16px;
}

.contact-info p {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 24px;
}

.contact-methods {
    margin-bottom: 24px;
}

.contact-method {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 16px;
    background-color: var(--bg-secondary);
    border-radius: 12px;
    margin-bottom: 12px;
}

.contact-method i {
    font-size: 1.5rem;
    color: var(--accent-blue);
}

.contact-method h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.contact-method p {
    margin: 0;
    font-size: 0.95rem;
}

.contact-method a {
    color: var(--accent-blue);
    text-decoration: none;
}

.contact-categories h3 {
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 12px;
}

.contact-categories ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.contact-categories li {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-bottom: 10px;
    display: flex;
    align-items: flex-start;
    gap: 10px;
}

.contact-categories li i {
    color: var(--accent-blue);
    margin-top: 3px;
}

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

.contact-form label {
    display: block;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.contact-form label .required {
    color: var(--accent-red);
}

.contact-form input,
.contact-form select,
.contact-form textarea {
    width: 100%;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: var(--transition);
}

.contact-form input:focus,
.contact-form select:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.contact-form textarea {
    resize: vertical;
    min-height: 120px;
}

.submit-btn {
    width: 100%;
    padding: 14px 24px;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-hover));
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.form-notice {
    color: var(--text-muted);
    font-size: 0.85rem;
    margin-top: 16px;
    text-align: center;
}

.faq-preview {
    max-width: 800px;
    margin: 0 auto;
    background-color: var(--bg-card);
    padding: 32px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.faq-preview h2 {
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.faq-preview h2 i {
    color: var(--accent-blue);
}

.faq-list .faq-item {
    border-bottom: 1px solid var(--border-color);
}

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

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .contact-wrapper {
        grid-template-columns: 1fr;
    }
    
    .service-grid {
        grid-template-columns: 1fr;
    }
    
    .legal-article,
    .about-section,
    .contact-info,
    .contact-form-section,
    .faq-preview {
        padding: 24px;
    }
    
    .footer-links {
        gap: 16px;
    }
    
    .footer-links a {
        font-size: 0.85rem;
    }
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    .hero-title h1 {
        font-size: 1.75rem;
    }
    
    .hero-title p {
        font-size: 0.95rem;
    }
    
    .calculator-card {
        padding: 24px 20px;
    }
    
    .input-tabs {
        flex-direction: column;
    }
    
    .tab-btn {
        padding: 14px;
    }
    
    .speed-options {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .result-value {
        font-size: 2.25rem;
    }
    
    .result-details {
        grid-template-columns: 1fr;
        gap: 12px;
    }
    
    .calc-cards {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .modal {
        max-width: 100%;
        margin: 10px;
        max-height: calc(100vh - 20px);
    }
    
    .modal-result-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .header-container {
        height: 56px;
    }
    
    .logo {
        font-size: 1.1rem;
    }
    
    .logo i {
        font-size: 1.25rem;
    }
    
    .hero-calculator {
        padding: 40px 0;
    }
    
    .hero-title h1 {
        font-size: 1.5rem;
        flex-direction: column;
        gap: 8px;
    }
    
    .calculator-card {
        padding: 20px 16px;
    }
    
    .calc-cards {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .calc-card {
        padding: 16px 12px;
    }
    
    .calc-card i {
        font-size: 1.5rem;
    }
    
    .calc-card span {
        font-size: 0.8rem;
    }
}

/* ===================================
   Utility Classes
   =================================== */
.hidden {
    display: none !important;
}

.text-center {
    text-align: center;
}

.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-4 { margin-bottom: 1rem; }

/* Input Row for side-by-side inputs */
.input-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

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

/* Radio/Checkbox styling */
.option-group {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.option-btn {
    flex: 1;
    min-width: 100px;
    padding: 12px 16px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    text-align: center;
    transition: var(--transition);
}

.option-btn:hover {
    border-color: var(--accent-blue);
}

.option-btn.active {
    background-color: var(--accent-blue);
    border-color: var(--accent-blue);
    color: #ffffff;
}

/* Info text */
.info-text {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 6px;
}

.info-text i {
    margin-right: 4px;
}

/* Error state */
.error {
    border-color: var(--accent-red) !important;
}

.error-text {
    color: var(--accent-red);
    font-size: 0.85rem;
    margin-top: 6px;
}

/* Success highlight */
.highlight {
    color: var(--accent-green);
    font-weight: 600;
}

/* ===================================
   SEO Content Section
   =================================== */
.seo-content {
    padding: 60px 0;
    background-color: var(--bg-primary);
    border-top: 1px solid var(--border-color);
}

.content-article {
    max-width: 800px;
    margin: 0 auto;
}

.content-article h2 {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--accent-blue);
}

.content-article h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-top: 32px;
    margin-bottom: 12px;
}

.content-article p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 16px;
}

.content-article ul {
    margin: 16px 0;
    padding-left: 24px;
}

.content-article li {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 8px;
}

.content-article strong {
    color: var(--text-primary);
}

/* Info Table */
.info-table {
    overflow-x: auto;
    margin: 20px 0;
}

.info-table table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--bg-card);
    border-radius: 12px;
    overflow: hidden;
}

.info-table th,
.info-table td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.info-table th {
    background-color: var(--bg-secondary);
    font-weight: 600;
    color: var(--text-primary);
}

.info-table td {
    color: var(--text-secondary);
}

.info-table tr:last-child td {
    border-bottom: none;
}

/* FAQ Section */
.faq-section {
    margin-top: 32px;
}

.faq-section h3 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

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

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

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 0;
    cursor: pointer;
    font-weight: 500;
    color: var(--text-primary);
    transition: var(--transition);
}

.faq-question:hover {
    color: var(--accent-blue);
}

.faq-question i {
    font-size: 0.85rem;
    color: var(--text-muted);
    transition: transform 0.3s ease;
}

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

.faq-answer p {
    padding-bottom: 16px;
    margin: 0;
}

/* Calculator Card as Link */
a.calc-card {
    text-decoration: none;
    display: block;
}

a.calc-card:hover {
    border-color: var(--accent-blue);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

/* Back Button */
.back-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    padding: 8px 16px;
    border-radius: 8px;
    transition: var(--transition);
    margin-bottom: 20px;
}

.back-btn:hover {
    color: var(--accent-blue);
    background-color: var(--bg-secondary);
}

/* Sub Calculator Page Hero */
.sub-hero {
    background: linear-gradient(135deg, var(--accent-blue) 0%, #1d4ed8 100%);
    padding: 40px 0;
    margin-bottom: 40px;
}

[data-theme="dark"] .sub-hero {
    background: linear-gradient(135deg, #1e3a5f 0%, #0f172a 100%);
}

.sub-hero .hero-title h1 {
    font-size: 2rem;
}

/* Related Calculators */
.related-calculators {
    padding: 40px 0;
    background-color: var(--bg-secondary);
}

.related-calculators h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 20px;
    text-align: center;
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
    max-width: 600px;
    margin: 0 auto;
}

@media (max-width: 768px) {
    .seo-content {
        padding: 40px 0;
    }
    
    .content-article h2 {
        font-size: 1.5rem;
    }
    
    .content-article h3 {
        font-size: 1.1rem;
    }
    
    .sub-hero .hero-title h1 {
        font-size: 1.5rem;
    }
}

/* ===================================
   Collapsible SEO Section
   =================================== */
.seo-collapsible {
    max-width: 800px;
    margin: 0 auto;
}

.seo-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    cursor: pointer;
    transition: var(--transition);
}

.seo-toggle:hover {
    border-color: var(--accent-blue);
    background-color: var(--bg-secondary);
}

.seo-toggle-text {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.seo-toggle-text i {
    color: var(--accent-blue);
    font-size: 1.1rem;
}

.seo-toggle-icon {
    font-size: 0.9rem;
    color: var(--text-muted);
    transition: transform 0.3s ease;
}

.seo-collapsible.open .seo-toggle-icon {
    transform: rotate(180deg);
}

.seo-collapsible.open .seo-toggle {
    border-radius: 12px 12px 0 0;
    border-bottom-color: transparent;
}

.seo-body {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-top: none;
    border-radius: 0 0 12px 12px;
}

.seo-collapsible.open .seo-body {
    max-height: 5000px;
}

.seo-body-inner {
    padding: 24px;
    padding-top: 12px;
}

/* Override article styles inside collapsible */
.seo-body .content-article {
    margin: 0;
}

.seo-body .content-article h2 {
    font-size: 1.5rem;
    margin-top: 0;
}

.seo-body .content-article h3 {
    margin-top: 24px;
}

@media (max-width: 768px) {
    .seo-toggle {
        padding: 16px 20px;
    }
    
    .seo-toggle-text {
        font-size: 0.9rem;
    }
    
    .seo-body-inner {
        padding: 20px 16px;
    }
}