/* ==========================================================================
   MSHIU.info - Main Stylesheet
   Modern Pro Design | Mobile-First | AdSense-Optimized
   ========================================================================== */

/* CSS Variables - Design System */
:root {
    /* Colors - Primary */
    --color-primary: #2563eb;
    --color-primary-dark: #1e40af;
    --color-primary-light: #3b82f6;
    --color-primary-lighter: #eff6ff;
    
    /* Colors - Category */
    --color-financial: #2563eb;
    --color-health: #059669;
    --color-webdev: #7c3aed;
    --color-text-cat: #dc2626;
    --color-math: #ea580c;
    --color-datetime: #0891b2;
    --color-conversion: #4f46e5;
    
    /* Neutral Colors */
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-bg-dark: #0f172a;
    --color-surface: #ffffff;
    --color-border: #e2e8f0;
    --color-border-light: #f1f5f9;
    
    /* Text Colors */
    --color-text: #1e293b;
    --color-text-secondary: #475569;
    --color-text-muted: #94a3b8;
    --color-text-light: #cbd5e1;
    --color-text-inverse: #ffffff;
    
    /* Status Colors */
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-info: #3b82f6;
    
    /* Typography */
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Consolas', monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -1px rgba(0,0,0,0.04);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -2px rgba(0,0,0,0.04);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 10px 10px -5px rgba(0,0,0,0.04);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Layout */
    --container-max: 1280px;
    --header-height: 72px;
    --sidebar-width: 320px;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
}

body {
    font-family: var(--font-body);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

img, svg {
    max-width: 100%;
    height: auto;
    display: block;
}

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

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

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

input, select, textarea {
    font-family: inherit;
    font-size: inherit;
}

ul, ol {
    list-style: none;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--font-size-3xl); }
h2 { font-size: var(--font-size-2xl); }
h3 { font-size: var(--font-size-xl); }
h4 { font-size: var(--font-size-lg); }

p {
    margin-bottom: var(--spacing-md);
}

/* ==========================================================================
   Layout Utilities
   ========================================================================== */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-narrow {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: 8px 16px;
    z-index: 1000;
    transition: top var(--transition-fast);
}

.skip-link:focus {
    top: 0;
}

/* ==========================================================================
   Top Bar
   ========================================================================== */
.top-bar {
    background: var(--color-bg-dark);
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
    padding: 8px 0;
}

.top-bar-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.top-bar-text {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.top-bar-text i {
    color: var(--color-success);
}

.top-bar-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.top-bar-links a {
    color: var(--color-text-light);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.top-bar-links a:hover {
    color: white;
}

.top-bar-links .separator {
    color: var(--color-text-muted);
}

/* ==========================================================================
   Site Header
   ========================================================================== */
.site-header {
    background: white;
    border-bottom: 1px solid var(--color-border);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
    transition: box-shadow var(--transition-base);
}

.site-header.scrolled {
    box-shadow: var(--shadow-md);
}

.main-nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    gap: var(--spacing-lg);
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 800;
    color: var(--color-primary);
    text-decoration: none;
    flex-shrink: 0;
}

.logo:hover {
    text-decoration: none;
}

.logo-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    color: white;
    border-radius: var(--radius-md);
    font-size: var(--font-size-lg);
}

.logo-text {
    letter-spacing: -0.5px;
}

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

/* Navigation Menu */
.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    flex: 1;
    justify-content: center;
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 10px 14px;
    color: var(--color-text);
    font-weight: 500;
    font-size: var(--font-size-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    text-decoration: none;
    white-space: nowrap;
}

.nav-link:hover {
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    text-decoration: none;
}

.nav-link i {
    font-size: 0.875em;
}

.dropdown-arrow {
    font-size: 0.7em !important;
    transition: transform var(--transition-fast);
}

.nav-item.dropdown:hover .dropdown-arrow {
    transform: rotate(180deg);
}

/* Dropdown */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    padding: var(--spacing-sm);
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: all var(--transition-base);
    z-index: 100;
}

.dropdown-menu-wide {
    min-width: 640px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
}

.nav-item.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: 8px 12px;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    text-decoration: none;
}

.dropdown-menu a:hover {
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    text-decoration: none;
}

.dropdown-section-title {
    display: block;
    font-weight: 600;
    color: var(--color-text);
    font-size: var(--font-size-sm);
    padding: 8px 12px;
    margin-bottom: 4px;
    border-bottom: 2px solid var(--color-primary-lighter);
}

/* Nav Actions */
.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.search-toggle, .mobile-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    color: var(--color-text);
    font-size: var(--font-size-lg);
    transition: all var(--transition-fast);
}

.search-toggle:hover, .mobile-toggle:hover {
    background: var(--color-primary-lighter);
    color: var(--color-primary);
}

.mobile-toggle {
    display: none;
}

.hamburger, .hamburger::before, .hamburger::after {
    display: block;
    width: 22px;
    height: 2px;
    background: currentColor;
    border-radius: 2px;
    transition: all var(--transition-base);
}

.hamburger::before, .hamburger::after {
    content: '';
    position: relative;
}

.hamburger::before { top: -6px; }
.hamburger::after { top: 5px; }

.mobile-toggle.active .hamburger {
    background: transparent;
}

.mobile-toggle.active .hamburger::before {
    transform: rotate(45deg);
    top: 0;
}

.mobile-toggle.active .hamburger::after {
    transform: rotate(-45deg);
    top: -2px;
}

/* Search Bar */
.search-bar {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
    background: var(--color-bg-alt);
}

.search-bar.active {
    max-height: 80px;
    border-top: 1px solid var(--color-border);
}

.search-container {
    position: relative;
    max-width: 600px;
    margin: var(--spacing-md) auto;
}

.search-icon {
    position: absolute;
    left: 16px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-muted);
}

#searchInput {
    width: 100%;
    padding: 12px 48px;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    background: white;
    transition: border-color var(--transition-fast);
}

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

.search-close {
    position: absolute;
    right: 12px;
    top: 50%;
    transform: translateY(-50%);
    width: 32px;
    height: 32px;
    border-radius: var(--radius-full);
    color: var(--color-text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
}

.search-close:hover {
    background: var(--color-border-light);
    color: var(--color-text);
}

.search-results {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    max-height: 400px;
    overflow-y: auto;
    display: none;
    z-index: 100;
}

.search-results.active {
    display: block;
}

.search-result-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: 12px 16px;
    border-bottom: 1px solid var(--color-border-light);
    color: var(--color-text);
    text-decoration: none;
    transition: background var(--transition-fast);
}

.search-result-item:hover, .search-result-item.highlighted {
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    text-decoration: none;
}

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

.search-result-icon {
    width: 36px;
    height: 36px;
    border-radius: var(--radius-md);
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.search-result-info {
    flex: 1;
    min-width: 0;
}

.search-result-name {
    font-weight: 600;
    font-size: var(--font-size-sm);
    margin-bottom: 2px;
}

.search-result-desc {
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.search-no-results {
    padding: var(--spacing-lg);
    text-align: center;
    color: var(--color-text-muted);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
    background: linear-gradient(135deg, #eff6ff 0%, #ffffff 100%);
    padding: var(--spacing-3xl) 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, rgba(37, 99, 235, 0.08) 0%, transparent 70%);
    border-radius: 50%;
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    background: white;
    border: 1px solid var(--color-border);
    padding: 8px 16px;
    border-radius: var(--radius-full);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-primary);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.hero-badge i {
    color: var(--color-success);
}

.hero h1 {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
    letter-spacing: -1px;
}

.hero h1 .accent {
    color: var(--color-primary);
    position: relative;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-search {
    max-width: 600px;
    margin: 0 auto var(--spacing-xl);
    position: relative;
}

.hero-search input {
    width: 100%;
    padding: 16px 20px 16px 52px;
    font-size: var(--font-size-base);
    border: 2px solid var(--color-border);
    border-radius: var(--radius-full);
    background: white;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
}

.hero-search input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

.hero-search i {
    position: absolute;
    left: 20px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--color-text-muted);
    font-size: var(--font-size-lg);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-2xl);
    flex-wrap: wrap;
    margin-top: var(--spacing-2xl);
}

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

.hero-stat-number {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    color: var(--color-primary);
    display: block;
    line-height: 1;
}

.hero-stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-top: 4px;
}

/* ==========================================================================
   Section Styles
   ========================================================================== */
.section {
    padding: var(--spacing-3xl) 0;
}

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

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: clamp(1.75rem, 4vw, 2.5rem);
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    max-width: 700px;
    margin: 0 auto;
}

/* ==========================================================================
   Category Grid
   ========================================================================== */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.category-card {
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
    text-decoration: none;
    color: var(--color-text);
    display: flex;
    flex-direction: column;
    position: relative;
    overflow: hidden;
}

.category-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--cat-color, var(--color-primary));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-base);
}

.category-card:hover {
    border-color: var(--cat-color, var(--color-primary));
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
    text-decoration: none;
}

.category-card:hover::before {
    transform: scaleX(1);
}

.category-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    background: var(--cat-color, var(--color-primary));
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
}

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

.category-card p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-md);
    flex: 1;
}

.category-card .category-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-sm);
    color: var(--cat-color, var(--color-primary));
    font-weight: 600;
}

/* ==========================================================================
   Tool Grid
   ========================================================================== */
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: var(--spacing-md);
}

.tool-card {
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    transition: all var(--transition-base);
    text-decoration: none;
    color: var(--color-text);
    display: flex;
    flex-direction: column;
    height: 100%;
}

.tool-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    text-decoration: none;
}

.tool-card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.tool-card-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-base);
    flex-shrink: 0;
}

.tool-card-title {
    font-size: var(--font-size-base);
    font-weight: 600;
    color: var(--color-text);
    margin: 0;
}

.tool-card-desc {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    flex: 1;
    margin-bottom: var(--spacing-sm);
}

.tool-card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
}

.tool-card-cat {
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-weight: 600;
}

/* ==========================================================================
   Page Layout - Tool Pages
   ========================================================================== */
.tool-page {
    padding: var(--spacing-2xl) 0;
}

.tool-layout {
    display: grid;
    grid-template-columns: 1fr var(--sidebar-width);
    gap: var(--spacing-2xl);
    align-items: start;
}

.tool-main {
    min-width: 0;
}

.tool-sidebar {
    position: sticky;
    top: calc(var(--header-height) + var(--spacing-md));
}

/* Breadcrumbs */
.breadcrumb-nav {
    margin-bottom: var(--spacing-lg);
}

.breadcrumb {
    display: flex;
    flex-wrap: wrap;
    gap: 0;
    padding: 0;
    list-style: none;
}

.breadcrumb-item {
    display: flex;
    align-items: center;
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

.breadcrumb-item:not(:last-child)::after {
    content: '/';
    margin: 0 var(--spacing-sm);
    color: var(--color-text-muted);
}

.breadcrumb-item a {
    color: var(--color-text-secondary);
    text-decoration: none;
}

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

.breadcrumb-item [aria-current] {
    color: var(--color-text);
    font-weight: 500;
}

/* Tool Header */
.tool-header {
    margin-bottom: var(--spacing-xl);
}

.tool-header-top {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.tool-header-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-md);
    background: var(--color-primary);
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-xl);
    flex-shrink: 0;
}

.tool-header-info h1 {
    margin: 0;
    font-size: var(--font-size-3xl);
}

.tool-header-meta {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
    margin-top: 4px;
}

.tool-header-meta span {
    display: flex;
    align-items: center;
    gap: 4px;
}

.tool-intro {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    line-height: 1.7;
}

/* Calculator Container */
.calculator-container {
    background: white;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-sm);
}

.calculator-title {
    font-size: var(--font-size-lg);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--color-border-light);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.calculator-title i {
    color: var(--color-primary);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

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

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    font-weight: 500;
    margin-bottom: var(--spacing-xs);
    color: var(--color-text);
    font-size: var(--font-size-sm);
}

.form-group .label-hint {
    font-weight: 400;
    color: var(--color-text-muted);
    font-size: var(--font-size-xs);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--color-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    background: white;
    color: var(--color-text);
    transition: all var(--transition-fast);
    font-family: inherit;
}

.form-control:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-control[readonly] {
    background: var(--color-bg-alt);
    color: var(--color-text);
    font-weight: 600;
}

select.form-control {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%23475569' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 20px;
    padding-right: 40px;
}

.input-group {
    display: flex;
    align-items: stretch;
}

.input-group .form-control {
    border-radius: var(--radius-md) 0 0 var(--radius-md);
}

.input-group-append {
    display: flex;
    align-items: center;
    padding: 0 16px;
    background: var(--color-bg-alt);
    border: 2px solid var(--color-border);
    border-left: none;
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    font-weight: 500;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 12px 24px;
    font-size: var(--font-size-base);
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    cursor: pointer;
    border: 2px solid transparent;
    text-decoration: none;
    font-family: inherit;
    line-height: 1;
}

.btn-primary {
    background: var(--color-primary);
    color: white;
}

.btn-primary:hover {
    background: var(--color-primary-dark);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: white;
    color: var(--color-text);
    border-color: var(--color-border);
}

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

.btn-block {
    width: 100%;
    display: flex;
}

.btn-lg {
    padding: 16px 32px;
    font-size: var(--font-size-lg);
}

/* Results Display */
.result-container {
    background: var(--color-primary-lighter);
    border: 2px solid var(--color-primary);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.result-container h3 {
    color: var(--color-primary-dark);
    font-size: var(--font-size-base);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-md);
}

.result-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

.result-item {
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
    text-align: center;
}

.result-item.highlight {
    background: var(--color-primary);
    color: white;
}

.result-label {
    font-size: var(--font-size-xs);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--color-text-muted);
    margin-bottom: 4px;
}

.result-item.highlight .result-label {
    color: rgba(255,255,255,0.85);
}

.result-value {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text);
}

.result-item.highlight .result-value {
    color: white;
}

.result-detail {
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--color-border);
}

.result-detail table {
    width: 100%;
    border-collapse: collapse;
}

.result-detail th, .result-detail td {
    padding: 10px 12px;
    text-align: left;
    border-bottom: 1px solid var(--color-border-light);
    font-size: var(--font-size-sm);
}

.result-detail th {
    font-weight: 600;
    color: var(--color-text-secondary);
    background: var(--color-bg-alt);
}

/* Content Sections */
.content-section {
    margin-bottom: var(--spacing-2xl);
}

.content-section h2 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-border-light);
    color: var(--color-text);
}

.content-section h3 {
    font-size: var(--font-size-lg);
    margin: var(--spacing-lg) 0 var(--spacing-sm);
    color: var(--color-text);
}

.content-section p {
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.content-section ul, .content-section ol {
    margin: var(--spacing-md) 0;
    padding-left: var(--spacing-xl);
}

.content-section li {
    margin-bottom: var(--spacing-sm);
    line-height: 1.7;
    color: var(--color-text-secondary);
}

.content-section ul li {
    list-style: disc;
}

.content-section ol li {
    list-style: decimal;
}

.content-section strong {
    color: var(--color-text);
    font-weight: 600;
}

/* Formula Box */
.formula-box {
    background: var(--color-bg-dark);
    color: #e2e8f0;
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: var(--font-size-lg);
    text-align: center;
    margin: var(--spacing-md) 0;
    overflow-x: auto;
    border-left: 4px solid var(--color-primary);
}

.formula-box .formula-label {
    font-family: var(--font-body);
    font-size: var(--font-size-xs);
    color: var(--color-text-light);
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: var(--spacing-sm);
    display: block;
}

/* Info Cards */
.info-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin: var(--spacing-lg) 0;
}

.info-card {
    background: var(--color-bg-alt);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    border-left: 4px solid var(--color-primary);
}

.info-card-title {
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--color-text);
}

.info-card-content {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    line-height: 1.6;
}

/* Example Box */
.example-box {
    background: #fffbeb;
    border: 1px solid #fef3c7;
    border-left: 4px solid var(--color-warning);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    margin: var(--spacing-md) 0;
}

.example-box-title {
    font-weight: 700;
    color: #92400e;
    margin-bottom: var(--spacing-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.example-box-content {
    color: var(--color-text-secondary);
    line-height: 1.8;
}

/* FAQ Section */
.faq-section {
    margin: var(--spacing-2xl) 0;
}

.faq-item {
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-sm);
    overflow: hidden;
}

.faq-question {
    padding: var(--spacing-md) var(--spacing-lg);
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--color-text);
    transition: background var(--transition-fast);
}

.faq-question:hover {
    background: var(--color-bg-alt);
}

.faq-question::after {
    content: '\f078';
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    transition: transform var(--transition-base);
    color: var(--color-text-muted);
}

.faq-item.active .faq-question::after {
    transform: rotate(180deg);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-base);
}

.faq-item.active .faq-answer {
    max-height: 1000px;
}

.faq-answer-inner {
    padding: 0 var(--spacing-lg) var(--spacing-md);
    color: var(--color-text-secondary);
    line-height: 1.8;
}

/* Related Tools */
.related-tools {
    margin: var(--spacing-2xl) 0;
}

.related-tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

/* ==========================================================================
   Sidebar
   ========================================================================== */
.sidebar-widget {
    background: white;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.sidebar-widget h3 {
    font-size: var(--font-size-base);
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--color-border-light);
}

.sidebar-tool-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.sidebar-tool-list a {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: 8px 12px;
    border-radius: var(--radius-sm);
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    transition: all var(--transition-fast);
    text-decoration: none;
}

.sidebar-tool-list a:hover {
    background: var(--color-primary-lighter);
    color: var(--color-primary);
    text-decoration: none;
}

.sidebar-tool-list a i {
    width: 20px;
    text-align: center;
    color: var(--color-text-muted);
}

.sidebar-tool-list a:hover i {
    color: var(--color-primary);
}

/* ==========================================================================
   Ad Containers
   ========================================================================== */
.ad-container {
    margin: var(--spacing-lg) 0;
    text-align: center;
    min-height: 90px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.ad-container::before {
    content: 'Advertisement';
    display: block;
    font-size: 10px;
    text-transform: uppercase;
    color: var(--color-text-muted);
    letter-spacing: 1px;
    margin-bottom: 4px;
    width: 100%;
}

/* ==========================================================================
   CTA Section
   ========================================================================== */
.cta-section {
    background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
    border-radius: var(--radius-xl);
    margin: var(--spacing-2xl) 0;
}

.cta-section h2 {
    color: white;
    font-size: var(--font-size-3xl);
    margin-bottom: var(--spacing-md);
}

.cta-section p {
    font-size: var(--font-size-lg);
    color: rgba(255,255,255,0.9);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.cta-section .btn {
    background: white;
    color: var(--color-primary);
    font-size: var(--font-size-lg);
    padding: 16px 32px;
}

.cta-section .btn:hover {
    background: var(--color-bg-alt);
    transform: translateY(-2px);
}

/* ==========================================================================
   Footer
   ========================================================================== */
.site-footer {
    background: var(--color-bg-dark);
    color: var(--color-text-light);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
    margin-top: var(--spacing-3xl);
}

.footer-widgets {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr 1fr;
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-about .footer-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 800;
    color: white;
    margin-bottom: var(--spacing-md);
    text-decoration: none;
}

.footer-about .footer-logo:hover {
    text-decoration: none;
}

.footer-about .logo-icon {
    width: 36px;
    height: 36px;
    font-size: var(--font-size-base);
}

.footer-description {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    line-height: 1.7;
    margin-bottom: var(--spacing-md);
}

.footer-contact a {
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
}

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

.footer-widget-title {
    color: white;
    font-size: var(--font-size-sm);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid rgba(255,255,255,0.1);
}

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

.footer-links a {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-bottom-content {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

.copyright {
    margin-bottom: 4px;
}

.footer-tagline {
    color: var(--color-text-light);
    font-style: italic;
}

.footer-badges {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 6px 12px;
    background: rgba(255,255,255,0.05);
    border: 1px solid rgba(255,255,255,0.1);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    color: var(--color-text-light);
}

.badge i {
    color: var(--color-success);
}

/* ==========================================================================
   Back to Top
   ========================================================================== */
#backToTop {
    position: fixed;
    bottom: 24px;
    right: 24px;
    width: 48px;
    height: 48px;
    border-radius: var(--radius-full);
    background: var(--color-primary);
    color: white;
    font-size: var(--font-size-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-base);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
}

#backToTop.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

#backToTop:hover {
    background: var(--color-primary-dark);
    transform: translateY(-4px);
}

/* ==========================================================================
   Page Content (About, Contact, etc.)
   ========================================================================== */
.page-content {
    max-width: 800px;
    margin: 0 auto;
    padding: var(--spacing-2xl) 0;
}

.page-content h1 {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-md);
    color: var(--color-text);
}

.page-content h2 {
    font-size: var(--font-size-2xl);
    margin: var(--spacing-xl) 0 var(--spacing-md);
    color: var(--color-text);
}

.page-content p {
    margin-bottom: var(--spacing-md);
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.page-content ul {
    margin: var(--spacing-md) 0;
    padding-left: var(--spacing-xl);
}

.page-content li {
    margin-bottom: var(--spacing-sm);
    list-style: disc;
    color: var(--color-text-secondary);
}

/* Contact Form */
.contact-form {
    background: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    margin-top: var(--spacing-lg);
}

.form-message {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
    display: none;
}

.form-message.success {
    background: #ecfdf5;
    color: #065f46;
    border: 1px solid #a7f3d0;
    display: block;
}

.form-message.error {
    background: #fef2f2;
    color: #991b1b;
    border: 1px solid #fecaca;
    display: block;
}

/* ==========================================================================
   Responsive Design
   ========================================================================== */
@media (max-width: 1024px) {
    .footer-widgets {
        grid-template-columns: 1fr 1fr 1fr;
    }
    
    .footer-about {
        grid-column: 1 / -1;
    }
    
    .tool-layout {
        grid-template-columns: 1fr;
    }
    
    .tool-sidebar {
        position: static;
        order: 2;
    }
}

@media (max-width: 768px) {
    :root {
        --header-height: 64px;
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
    
    /* Mobile Navigation */
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        bottom: 0;
        background: white;
        flex-direction: column;
        align-items: stretch;
        padding: var(--spacing-md);
        gap: 0;
        overflow-y: auto;
        transform: translateX(100%);
        transition: transform var(--transition-base);
        z-index: 999;
    }
    
    .nav-menu.active {
        transform: translateX(0);
    }
    
    .nav-item {
        width: 100%;
    }
    
    .nav-link {
        padding: 14px 16px;
        border-radius: var(--radius-md);
        font-size: var(--font-size-base);
        justify-content: space-between;
        border-bottom: 1px solid var(--color-border-light);
    }
    
    .dropdown-menu, .dropdown-menu-wide {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        border: none;
        padding: 0 0 0 var(--spacing-md);
        margin: 0;
        display: none;
        grid-template-columns: 1fr;
        background: transparent;
    }
    
    .nav-item.dropdown.active .dropdown-menu {
        display: block;
    }
    
    .dropdown-menu a {
        padding: 10px 12px;
        border-bottom: 1px solid var(--color-border-light);
    }
    
    .mobile-toggle {
        display: flex;
    }
    
    /* Hero */
    .hero {
        padding: var(--spacing-2xl) 0;
    }
    
    .hero-stats {
        gap: var(--spacing-lg);
    }
    
    .hero-stat-number {
        font-size: var(--font-size-2xl);
    }
    
    /* Tool Page */
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .tool-header-top {
        flex-direction: column;
        align-items: flex-start;
        text-align: left;
    }
    
    .tool-header-info h1 {
        font-size: var(--font-size-2xl);
    }
    
    .calculator-container {
        padding: var(--spacing-md);
    }
    
    /* Footer */
    .footer-widgets {
        grid-template-columns: 1fr 1fr;
        gap: var(--spacing-lg);
    }
    
    .footer-about {
        grid-column: 1 / -1;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
    
    /* Section */
    .section {
        padding: var(--spacing-2xl) 0;
    }
    
    .category-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .footer-widgets {
        grid-template-columns: 1fr;
    }
    
    .top-bar-content {
        flex-direction: column;
        gap: 4px;
        text-align: center;
    }
    
    .hero h1 {
        font-size: var(--font-size-2xl);
    }
    
    .hero-subtitle {
        font-size: var(--font-size-base);
    }
    
    .tool-grid {
        grid-template-columns: 1fr;
    }
    
    .calculator-container {
        padding: var(--spacing-sm);
    }
    
    .result-grid {
        grid-template-columns: 1fr;
    }
}

/* ==========================================================================
   Print Styles
   ========================================================================== */
@media print {
    .site-header, .site-footer, .top-bar, .ad-container, #backToTop, .nav-actions, .related-tools, .tool-sidebar {
        display: none;
    }
    
    body {
        color: black;
    }
    
    .calculator-container {
        border: 1px solid #ccc;
        page-break-inside: avoid;
    }
}

/* ==========================================================================
   Accessibility
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

:focus-visible {
    outline: 3px solid var(--color-primary);
    outline-offset: 2px;
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}