/* ===================================
   GLOBAL STYLES
   =================================== */

:root {
    --primary-color: #4A90E2;
    --secondary-color: #50C878;
    --accent-color: #FF6B6B;
    --dark-bg: #1A1A1A;
    --light-bg: #F8FAFB;
    --text-dark: #2C3E50;
    --text-light: #7F8C8D;
    --border-color: #E1E8ED;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.15);

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 2.5rem;

    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    color: var(--text-dark);
    background-color: #FFFFFF;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===================================
   NAVIGATION
   =================================== */

.navbar {
    background-color: #FFFFFF;
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.logo-symbol {
    font-size: 1.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    transition: color 0.3s ease;
    padding: var(--spacing-xs) var(--spacing-sm);
}

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

.hamburger {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    gap: 6px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    transition: 0.3s;
}

/* ===================================
   HERO SECTION
   =================================== */

.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, #357ABD 100%);
    color: white;
    padding: 6rem var(--spacing-md);
    text-align: center;
}

.hero h1 {
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    font-weight: 600;
    border-radius: 8px;
    cursor: pointer;
    transition: transform 0.3s, box-shadow 0.3s;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
}

/* ===================================
   QUICK ANSWER BOX
   =================================== */

.quick-answer {
    background-color: var(--light-bg);
    padding: var(--spacing-xl) var(--spacing-md);
    border-top: 4px solid var(--primary-color);
}

.qa-box {
    background-color: white;
    padding: var(--spacing-lg);
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.qa-box h2 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-xl);
}

.formula-box {
    background-color: var(--light-bg);
    padding: var(--spacing-lg);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
    text-align: center;
}

.formula {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    font-size: var(--font-size-lg);
}

.formula-element {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.element-label {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    margin-bottom: 4px;
}

.element-value {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--primary-color);
}

.quick-example {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background-color: #E8F4F8;
    border-left: 4px solid var(--secondary-color);
    border-radius: 4px;
}

/* ===================================
   SECTIONS GENERAL
   =================================== */

section {
    padding: var(--spacing-xl) var(--spacing-md);
}

section h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-lg);
    color: var(--text-dark);
    text-align: center;
}

.section-subtitle {
    text-align: center;
    color: var(--text-light);
    margin-bottom: var(--spacing-lg);
    font-size: var(--font-size-lg);
}

/* ===================================
   FORMULA SECTION
   =================================== */

.formula-section {
    background-color: var(--light-bg);
}

.formula-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-xl) 0;
}

.formula-card {
    background-color: white;
    padding: var(--spacing-lg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    border-top: 4px solid var(--primary-color);
}

.formula-card h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-lg);
}

.large-formula {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-align: center;
    margin: var(--spacing-lg) 0;
    font-family: 'Georgia', serif;
}

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

.formula-alt p {
    margin: var(--spacing-md) 0;
    font-size: var(--font-size-lg);
}

.formula-card ul {
    list-style-position: inside;
    color: var(--text-dark);
}

.formula-card li {
    margin: var(--spacing-sm) 0;
}

.concept-box {
    background-color: white;
    padding: var(--spacing-lg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--secondary-color);
    margin-top: var(--spacing-xl);
}

.concept-box h3 {
    color: var(--secondary-color);
    margin-bottom: var(--spacing-md);
}

.concept-box ul {
    margin-left: var(--spacing-md);
}

.concept-box li {
    margin: var(--spacing-sm) 0;
}

/* ===================================
   TYPES SECTION
   =================================== */

.types-section {
    background-color: #FFFFFF;
}

.types-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.type-card {
    background: linear-gradient(135deg, var(--light-bg) 0%, #F0F5FF 100%);
    padding: var(--spacing-lg);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
    transition: transform 0.3s, box-shadow 0.3s;
}

.type-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.type-card h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-lg);
}

.type-card p {
    color: var(--text-dark);
    line-height: 1.6;
}

/* ===================================
   EXAMPLES SECTION
   =================================== */

.examples-section {
    background-color: var(--light-bg);
}

.examples-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.example-card {
    background-color: white;
    padding: var(--spacing-lg);
    border-radius: 8px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s, box-shadow 0.3s;
}

.example-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.example-card h3 {
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-size-lg);
}

.density-value {
    color: var(--primary-color);
    font-size: 1.75rem;
    font-weight: 700;
    margin: var(--spacing-sm) 0;
    font-family: 'Georgia', serif;
}

.example-card p {
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

/* ===================================
   GUIDES SECTION
   =================================== */

.guides-section {
    background-color: #FFFFFF;
}

.guides-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.guide-card {
    background-color: var(--light-bg);
    padding: var(--spacing-lg);
    border-radius: 8px;
    border-left: 4px solid var(--secondary-color);
    transition: transform 0.3s, box-shadow 0.3s;
}

.guide-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.guide-card h3 {
    margin-bottom: var(--spacing-sm);
}

.guide-card h3 a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s;
}

.guide-card h3 a:hover {
    color: var(--secondary-color);
}

.guide-card p {
    color: var(--text-light);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.read-more {
    color: var(--secondary-color);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.3s;
}

.read-more:hover {
    color: var(--primary-color);
}

/* ===================================
   FAQ SECTION
   =================================== */

.faq-section {
    background-color: var(--light-bg);
}

.faq-container {
    max-width: 800px;
    margin: var(--spacing-xl) auto 0;
}

.faq-item {
    background-color: white;
    margin-bottom: var(--spacing-md);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: box-shadow 0.3s;
}

.faq-item:hover {
    box-shadow: var(--shadow-lg);
}

.faq-item summary {
    padding: var(--spacing-lg);
    cursor: pointer;
    font-weight: 600;
    color: var(--primary-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
    transition: background-color 0.3s;
}

.faq-item summary:hover {
    background-color: var(--light-bg);
}

.faq-item summary::after {
    content: '▼';
    font-size: 0.75rem;
    transition: transform 0.3s;
}

.faq-item[open] summary::after {
    transform: rotate(180deg);
}

.faq-content {
    padding: 0 var(--spacing-lg) var(--spacing-lg);
    background-color: #FAFBFC;
    border-top: 1px solid var(--border-color);
}

.faq-content p {
    color: var(--text-dark);
    line-height: 1.7;
    margin-bottom: var(--spacing-sm);
}

.faq-footer {
    text-align: center;
    margin-top: var(--spacing-xl);
}

.faq-footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
}

.faq-footer a:hover {
    text-decoration: underline;
}

/* ===================================
   MORE TOOLS SECTION
   =================================== */

.more-tools {
    background-color: #FFFFFF;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.tool-card {
    background: linear-gradient(135deg, var(--primary-color) 0%, #357ABD 100%);
    color: white;
    padding: var(--spacing-lg);
    border-radius: 8px;
    text-align: center;
    transition: transform 0.3s, box-shadow 0.3s;
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.tool-card h3 {
    margin-bottom: var(--spacing-sm);
}

.tool-card h3 a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.tool-card h3 a:hover {
    opacity: 0.9;
}

.tool-card p {
    font-size: var(--font-size-sm);
    opacity: 0.95;
}

/* ===================================
   FOOTER
   =================================== */

.footer {
    background-color: #2C3E50;
    color: #ECF0F1;
    padding: var(--spacing-xl) var(--spacing-md) var(--spacing-lg);
}

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

.footer-section h4 {
    color: white;
    margin-bottom: var(--spacing-md);
    font-size: var(--font-size-lg);
}

.footer-section p {
    line-height: 1.6;
    margin-bottom: var(--spacing-sm);
}

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

.footer-section li {
    margin-bottom: var(--spacing-sm);
}

.footer-section a {
    color: #ECF0F1;
    text-decoration: none;
    transition: color 0.3s;
}

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

.footer-bottom {
    border-top: 1px solid rgba(236, 240, 241, 0.3);
    padding-top: var(--spacing-lg);
    text-align: center;
    font-size: var(--font-size-sm);
}

.footer-bottom p {
    margin-bottom: var(--spacing-xs);
}

.footer-bottom a {
    color: var(--secondary-color);
    text-decoration: none;
}

.footer-bottom a:hover {
    text-decoration: underline;
}

/* ===================================
   UTILITY CLASSES
   =================================== */

.hidden {
    display: none !important;
}

.highlight {
    background-color: #FFF3CD;
    padding: 2px 4px;
    border-radius: 3px;
}

/* ===================================
   RESPONSIVE DESIGN
   =================================== */

@media (max-width: 768px) {
    .nav-menu {
        gap: var(--spacing-sm);
        font-size: var(--font-size-sm);
    }

    .nav-link {
        padding: var(--spacing-xs) var(--spacing-xs);
    }

    .hero h1 {
        font-size: var(--font-size-2xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    section h2 {
        font-size: var(--font-size-xl);
    }

    .formula {
        gap: var(--spacing-sm);
    }

    .large-formula {
        font-size: 2rem;
    }

    .examples-grid,
    .types-grid,
    .tools-grid,
    .formula-grid,
    .guides-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }

    .navbar .container {
        padding: var(--spacing-sm);
    }

    .nav-menu {
        display: none;
        gap: var(--spacing-xs);
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: white;
        padding: var(--spacing-sm);
    }

    .nav-menu.active {
        display: flex;
    }

    .hamburger {
        display: flex;
    }

    .hero {
        padding: 3rem var(--spacing-sm);
    }

    .hero h1 {
        font-size: var(--font-size-xl);
    }

    .hero-subtitle {
        font-size: var(--font-size-sm);
    }

    .cta-button {
        padding: var(--spacing-sm) var(--spacing-md);
        font-size: var(--font-size-sm);
    }

    section {
        padding: var(--spacing-lg) var(--spacing-sm);
    }

    section h2 {
        font-size: var(--font-size-lg);
    }

    .formula-box {
        padding: var(--spacing-md);
    }

    .formula {
        gap: var(--spacing-sm);
        font-size: var(--font-size-base);
    }

    .large-formula {
        font-size: 1.5rem;
    }

    .density-value {
        font-size: 1.5rem;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

    .guide-hero-content {
        flex-direction: column;
    }

    .guide-hero-left,
    .guide-hero-right {
        width: 100% !important;
    }
}

/* ===================================
   GUIDE HERO SECTION (REDESIGNED)
   =================================== */

.guide-hero-2col {
    background: linear-gradient(135deg, var(--primary-color) 0%, #357ABD 100%);
    color: white;
    padding: 5rem var(--spacing-md);
    position: relative;
    overflow: hidden;
}

.guide-hero-2col::before {
    content: '';
    position: absolute;
    top: 0;
    right: -100px;
    width: 500px;
    height: 500px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 50%;
    z-index: 0;
}

.guide-hero-2col .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    position: relative;
    z-index: 1;
}

.guide-hero-content {
    display: flex;
    gap: var(--spacing-xl);
    align-items: center;
}

.guide-hero-left {
    flex: 1;
    min-width: 300px;
}

.guide-hero-right {
    display: none;
}

.guide-hero-2col h1 {
    font-size: 3.5rem;
    margin-bottom: var(--spacing-md);
    line-height: 1.1;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.guide-hero-2col p {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
    line-height: 1.7;
    max-width: 600px;
}

.guide-hero-meta {
    display: flex;
    gap: var(--spacing-lg);
    font-size: 0.95rem;
    opacity: 0.85;
}

.guide-hero-meta span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.guide-hero-calculator {
    display: none;
}

.guide-hero-calculator iframe {
    width: 100%;
    border: none;
    border-radius: 8px;
    overflow: hidden;
    display: block;
}

/* ===================================
   CALCULATOR SECTION (BELOW HERO)
   =================================== */

.guide-calculator-section {
    background: var(--light-bg);
    padding: var(--spacing-xl) var(--spacing-md);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.guide-calculator-section .container {
    max-width: 1200px;
    margin: 0 auto;
}

.calculator-section-header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.calculator-section-header h2 {
    font-size: var(--font-size-2xl);
    color: var(--text-dark);
    margin-bottom: var(--spacing-sm);
}

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

.guide-calculator-wrapper {
    background: transparent;
    border-radius: 0;
    box-shadow: none;
    padding: 0;
    overflow: visible;
}

.guide-calculator-wrapper iframe {
    width: 100%;
    border: none;
    border-radius: 0;
    overflow: visible;
    display: block;
    height: auto;
    min-height: auto;
}

/* ===================================
   GUIDE CONTENT SECTION
   =================================== */

.guide-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 3rem var(--spacing-md);
}

.breadcrumb {
    margin-bottom: 2rem;
    font-size: 0.9rem;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.breadcrumb a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.3s ease;
    font-weight: 500;
}

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

.guide-toc {
    background: white;
    padding: var(--spacing-lg);
    border-radius: 12px;
    margin: var(--spacing-xl) 0;
    border: 1px solid var(--border-color);
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.04);
    transition: all 0.3s ease;
}

.guide-toc:hover {
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

.guide-toc h2 {
    color: var(--primary-color);
    margin-top: 0;
    margin-bottom: var(--spacing-md);
    font-size: 1.1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.guide-toc ul {
    list-style: none;
    padding-left: 0;
}

.guide-toc li {
    margin: 0.75rem 0;
}

.guide-toc a {
    color: var(--text-dark);
    text-decoration: none;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.25rem 0;
}

.guide-toc a::before {
    content: '→';
    color: var(--primary-color);
    opacity: 0;
    transition: opacity 0.2s ease;
    width: 1rem;
    text-align: center;
}

.guide-toc a:hover {
    color: var(--primary-color);
    padding-left: 0.5rem;
}

.guide-toc a:hover::before {
    opacity: 1;
}

.guide-section {
    margin: 3rem 0;
}

.guide-section h2 {
    color: var(--text-dark);
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--primary-color);
    position: relative;
}

.guide-section h2::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    height: 2px;
    width: 0;
    background: var(--secondary-color);
    transition: width 0.3s ease;
}

.guide-section:hover h2::after {
    width: 100%;
}

.guide-section h3 {
    color: var(--text-dark);
    font-size: 1.35rem;
    font-weight: 600;
    margin-top: 2rem;
    margin-bottom: var(--spacing-md);
}

.guide-section p {
    color: var(--text-dark);
    line-height: 1.8;
    font-size: 1rem;
    margin-bottom: var(--spacing-md);
}

.guide-section ul,
.guide-section ol {
    margin: var(--spacing-lg) 0 var(--spacing-lg) var(--spacing-lg);
    line-height: 1.8;
}

.guide-section li {
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

/* ===================================
   EMBEDDED CALCULATOR WIDGET STYLES
   =================================== */

.widget-container {
    background: white;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    padding: 25px;
    width: 50%;
    max-width: 600px;
    margin: 0 auto;
    font-size: 14px;
}

.widget-header {
    background: linear-gradient(135deg, #4A90E2 0%, #357ABD 100%);
    color: white;
    padding: 20px;
    border-radius: 8px;
    margin: -25px -25px 25px -25px;
    text-align: center;
}

.widget-header h2 {
    font-size: 1.5rem;
    margin: 0;
    font-weight: 600;
}

.widget-header p {
    margin: 8px 0 0 0;
    opacity: 0.9;
    font-size: 0.9rem;
}

.input-group {
    margin-bottom: 18px;
}

.input-group label {
    display: block;
    font-weight: 600;
    color: #2C3E50;
    margin-bottom: 6px;
    font-size: 0.9rem;
}

.input-wrapper {
    display: flex;
    gap: 10px;
}

.input-group input[type="number"] {
    flex: 1;
    padding: 10px 12px;
    border: 2px solid #E1E8ED;
    border-radius: 4px;
    font-size: 14px;
    transition: border-color 0.2s;
}

.input-group input[type="number"]:focus {
    outline: none;
    border-color: #4A90E2;
}

.input-group select {
    padding: 10px 12px;
    border: 2px solid #E1E8ED;
    border-radius: 4px;
    font-size: 14px;
    background: white;
    cursor: pointer;
    transition: border-color 0.2s;
}

.input-group select:focus {
    outline: none;
    border-color: #4A90E2;
}

.button-group {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.button-group button {
    flex: 1;
    padding: 12px 16px;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-calculate {
    background: linear-gradient(135deg, #4A90E2 0%, #357ABD 100%);
    color: white;
}

.btn-calculate:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(74, 144, 226, 0.3);
}

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

.btn-clear {
    background: #F0F5FF;
    color: #4A90E2;
    border: 2px solid #4A90E2;
}

.btn-clear:hover {
    background: #E8F1FF;
}

.result-box {
    background: #E8F4F8;
    border: 2px solid #50C878;
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 15px;
    display: none;
}

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

.result-label {
    color: #2C3E50;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 8px;
}

.result-value {
    font-size: 1.8rem;
    color: #4A90E2;
    font-weight: bold;
    word-break: break-all;
}

.result-actions {
    display: flex;
    gap: 10px;
    margin-top: 12px;
}

.copy-btn, .share-btn {
    flex: 1;
    padding: 8px 12px;
    background: white;
    border: 1px solid #E1E8ED;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 600;
    color: #4A90E2;
    transition: all 0.2s;
}

.copy-btn:hover, .share-btn:hover {
    background: #F8FAFB;
    border-color: #4A90E2;
}

.copy-btn.copied {
    background: #50C878;
    color: white;
    border-color: #50C878;
}

.tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    border-bottom: 2px solid #E1E8ED;
}

.tab-btn {
    padding: 10px 16px;
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    color: #666;
    font-weight: 600;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.2s;
}

.tab-btn.active {
    color: #4A90E2;
    border-bottom-color: #4A90E2;
}

.tab-content {
    display: none;
}

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

.formula-display {
    background: #F0F5FF;
    padding: 12px;
    border-radius: 4px;
    text-align: center;
    margin: 15px 0;
    font-weight: bold;
    color: #4A90E2;
    font-size: 0.95rem;
}

.info-box {
    background: #F8FAFB;
    padding: 12px;
    border-radius: 4px;
    margin-top: 15px;
    font-size: 0.85rem;
    color: #666;
    border-left: 3px solid #4A90E2;
}

.widget-footer {
    text-align: center;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid #E1E8ED;
    font-size: 0.8rem;
    color: #999;
}

.widget-footer a {
    color: #4A90E2;
    text-decoration: none;
}

.widget-footer a:hover {
    text-decoration: underline;
}

/* ===================================
   RESPONSIVE GUIDE HERO
   =================================== */

@media (max-width: 1024px) {
    .guide-hero-2col {
        padding: 4rem var(--spacing-md);
    }

    .guide-hero-2col h1 {
        font-size: 3rem;
    }

    .guide-calculator-wrapper {
        padding: 0;
    }

    .widget-container {
        width: 60%;
    }
}

@media (max-width: 768px) {
    .guide-hero-2col {
        padding: 3rem var(--spacing-md);
    }

    .guide-hero-2col::before {
        width: 300px;
        height: 300px;
        right: -50px;
    }

    .guide-hero-2col h1 {
        font-size: 2.5rem;
    }

    .guide-hero-2col p {
        font-size: var(--font-size-base);
    }

    .guide-hero-meta {
        flex-direction: column;
        gap: var(--spacing-sm);
    }

    .guide-container {
        padding: 2rem var(--spacing-md);
    }

    .guide-section {
        margin: 2rem 0;
    }

    .guide-section h2 {
        font-size: 1.5rem;
    }

    .guide-section h3 {
        font-size: 1.15rem;
    }

    .guide-calculator-section {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .guide-calculator-wrapper {
        padding: 0;
    }

    .widget-container {
        width: 75%;
    }
}

@media (max-width: 480px) {
    .guide-hero-2col {
        padding: 2rem var(--spacing-sm);
    }

    .guide-hero-2col::before {
        width: 200px;
        height: 200px;
        right: -80px;
    }

    .guide-hero-2col h1 {
        font-size: 1.75rem;
        margin-bottom: var(--spacing-sm);
    }

    .guide-hero-2col p {
        font-size: var(--font-size-sm);
        margin-bottom: var(--spacing-md);
    }

    .guide-hero-meta {
        flex-direction: column;
        gap: var(--spacing-xs);
        font-size: 0.85rem;
    }

    .guide-container {
        padding: 1.5rem var(--spacing-sm);
    }

    .guide-section {
        margin: 1.5rem 0;
    }

    .guide-section h2 {
        font-size: 1.25rem;
        margin-bottom: var(--spacing-md);
    }

    .guide-section h3 {
        font-size: 1rem;
        margin-top: 1.5rem;
    }

    .guide-toc {
        padding: var(--spacing-md);
        margin: var(--spacing-lg) 0;
    }

    .guide-toc h2 {
        font-size: 0.95rem;
    }

    .guide-toc a {
        font-size: var(--font-size-sm);
    }

    .guide-calculator-section {
        padding: var(--spacing-lg) var(--spacing-sm);
    }

    .calculator-section-header h2 {
        font-size: 1.35rem;
    }

    .guide-calculator-wrapper {
        padding: var(--spacing-md);
    }

    .guide-calculator-wrapper iframe {
        min-height: 500px;
    }

    .breadcrumb {
        font-size: 0.8rem;
    }

    .widget-container {
        width: 90%;
        padding: 20px;
    }

    .widget-header {
        margin: -20px -20px 20px -20px;
        padding: 15px;
    }

    .widget-header h2 {
        font-size: 1.2rem;
    }

    .widget-header p {
        font-size: 0.8rem;
    }
}