/* CSS Variables for Brand Design System */
:root {
    --color-ink: #0F172A;        /* Slate 900 */
    --color-muted: #475569;      /* Slate 600 */
    --color-bg-main: #F8FAFC;    /* Slate 50 */
    --color-bg-card: #FFFFFF;    /* White */
    --color-accent: #4F46E5;     /* Indigo 600 */
    --color-accent-hover: #4338CA; /* Indigo 700 */
    --color-accent-light: #EEF2F6; /* Light indigo/gray for tags */
    --color-accent-on-dark: #A5B4FC; /* Indigo 300 for dark backgrounds */
    --color-success: #047857;    /* Emerald 700 */
    --color-success-bg: #D1FAE5; /* Emerald 100 */
    --color-error: #B91C1C;      /* Red 700 */
    --color-error-bg: #FEE2E2;   /* Red 100 */
    --color-border: #E2E8F0;     /* Slate 200 */
    
    --font-heading: 'Sora', 'Inter', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 16px;
    
    --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 1px 3px rgba(15, 23, 42, 0.06);
    --shadow-lg: 0 8px 24px rgba(15, 23, 42, 0.08), 0 2px 6px rgba(15, 23, 42, 0.04);
    
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html,body {
    overflow-x: hidden;
    max-width: 100%;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-body);
    background-color: var(--color-bg-main);
    color: var(--color-ink);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.25;
    margin-bottom: 0.5rem;
    color: var(--color-ink);
}

h1 {
    font-size: 2.25rem;
}

h2 {
    font-size: 1.75rem;
}

h3 {
    font-size: 1.25rem;
}

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

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

/* Global Shell Layout */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Navigation & Header System (BusinessCalc Mega-Menu Port - Indigo) */
.site-header, header {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: var(--color-bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
}

.header-inner, .nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
    height: 72px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
}

.brand-logo, .logo-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-heading);
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-ink);
    flex-shrink: 0;
    text-decoration: none;
}

.brand-logo:hover, .logo-link:hover {
    text-decoration: none;
    color: var(--color-ink);
}

.nav-desktop, .nav-links {
    display: flex;
    align-items: center;
}

.nav-links-list {
    display: flex;
    gap: 1.25rem;
    align-items: center;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-link {
    color: var(--color-muted);
    font-size: 0.9375rem;
    font-weight: 600;
    padding: 0.5rem 0.75rem;
    border-radius: 0.5rem;
    background: transparent;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.25rem;
    text-decoration: none;
    transition: color 0.15s ease, background-color 0.15s ease;
}

.nav-link:hover, .nav-link.active {
    color: var(--color-ink);
    background-color: var(--color-bg-main);
    text-decoration: none;
}

/* Mega Menu (Pure CSS Hover & Focus + Click-to-Open) */
.nav-item-dropdown {
    position: static;
}

.nav-item-dropdown.nav-dropdown-simple {
    position: relative;
}

.mega-menu {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    max-width: 1100px;
    margin: 8px auto 0;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: 1rem;
    box-shadow: 0 20px 40px -12px rgba(15, 23, 42, 0.18);
    padding: 1.75rem 2rem;
    display: none;
    z-index: 1001;
}

.nav-dropdown-simple > .mega-menu {
    left: auto;
    right: 0;
    width: 220px;
    max-width: 220px;
    padding: 1rem 1.25rem;
    margin-top: 8px;
    box-shadow: 0 10px 25px -5px rgba(15, 23, 42, 0.15);
}

.nav-item-dropdown.open > .mega-menu,
.nav-item-dropdown:hover > .mega-menu,
.nav-item-dropdown:focus-within > .mega-menu {
    display: block;
}

.nav-item-dropdown::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    height: 12px;
}

.mega-menu-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 1.5rem;
}

.mega-col {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.mega-col .eyebrow {
    font-family: var(--font-heading);
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--color-accent);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding-bottom: 0.4rem;
    border-bottom: 1px solid var(--color-border);
}

.mega-item {
    display: block;
    padding: 0.25rem 0;
    text-decoration: none;
}

.mega-item-title {
    color: var(--color-ink);
    font-size: 0.88rem;
    font-weight: 600;
    transition: color 0.15s ease;
}

.mega-item-sub {
    display: block;
    color: var(--color-muted);
    font-size: 0.78rem;
}

.mega-item:hover .mega-item-title {
    color: var(--color-accent);
}

.mega-view-all {
    color: var(--color-accent);
    font-weight: 700;
    font-size: 0.85rem;
    margin-top: 0.4rem;
    text-decoration: none;
    display: inline-block;
}

.mega-view-all:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}

/* Ask Jack Pill with Pulsing Sonar Glow Ring (Indigo) */
.nav-jack {
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    isolation: isolate;
    background: linear-gradient(135deg, rgba(79,70,229,0.16), rgba(67,56,202,0.10));
    border: 1px solid var(--color-accent);
    color: var(--color-accent);
    font-weight: 700;
    font-size: 0.9rem;
    padding: 6px 14px 6px 8px;
    border-radius: 999px;
    text-decoration: none;
    transition: transform 0.15s, background 0.2s;
}

.nav-jack:hover {
    transform: translateY(-1px);
    background: linear-gradient(135deg, rgba(79,70,229,0.26), rgba(67,56,202,0.16));
    color: var(--color-accent);
    text-decoration: none;
}

.nav-jack::after {
    content: "";
    position: absolute;
    inset: -1px;
    border-radius: 999px;
    z-index: -1;
    border: 1px solid var(--color-accent);
    animation: ajPulse 2.2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

.jack-avatar {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--color-accent);
    color: #FFFFFF;
    font-weight: 800;
    font-size: 0.72rem;
}

@keyframes ajPulse {
    0% { transform: scale(1); opacity: 0.55; }
    70%, 100% { transform: scale(1.45); opacity: 0; }
}

@media (prefers-reduced-motion: reduce) {
    .nav-jack::after { animation: none; }
}

/* Button System (Indigo adaptation of BusinessCalc .btn) */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    font-family: var(--font-body);
    font-weight: 600;
    font-size: 0.9375rem;
    line-height: 1;
    padding: 0.75rem 1.5rem;
    border-radius: 999px;
    border: 1px solid transparent;
    min-height: 44px;
    text-decoration: none;
    white-space: nowrap;
    cursor: pointer;
    transition: background-color 0.15s, border-color 0.15s, color 0.15s;
}

.btn-primary {
    background: var(--color-accent);
    color: #FFFFFF;
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background: var(--color-accent-hover);
    border-color: var(--color-accent-hover);
    color: #FFFFFF;
    text-decoration: none;
}

.btn-secondary {
    background: var(--color-bg-card);
    color: var(--color-ink);
    border-color: var(--color-border);
}

.btn-secondary:hover {
    border-color: var(--color-accent);
    text-decoration: none;
}

.btn-ghost {
    background: transparent;
    color: var(--color-accent);
    border-color: transparent;
}

.btn-ghost:hover {
    color: var(--color-accent-hover);
    text-decoration: none;
}

.btn-sm {
    min-height: 32px;
    padding: 0.35rem 0.85rem;
    font-size: 0.82rem;
}

/* Hero Button Group */
.hero-btn-group {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    align-items: center;
    justify-content: flex-start;
    margin-top: 1.25rem;
}

@media (max-width: 560px) {
    .hero-btn-group {
        flex-direction: column;
        width: 100%;
    }
    .hero-btn-group .btn {
        width: 100%;
        justify-content: center;
    }
}



/* Mobile Nav Toggle & Menu Drawer (NAV_AND_POLISH_SPEC §5b) */
.mobile-nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-ink);
    cursor: pointer;
    font-size: 1.5rem;
    padding: 0.25rem;
    z-index: 210;
}

body.menu-open {
    overflow: hidden;
}

.mobile-menu {
    display: none;
    position: fixed;
    inset: 60px 0 0 0;
    z-index: 190;
    background-color: var(--color-bg-card);
    overflow-y: auto;
    flex-direction: column;
    padding: 1.5rem;
    gap: 1rem;
    box-shadow: var(--shadow-lg);
    box-sizing: border-box;
}

.mobile-menu.open {
    display: flex;
}

.m-trade {
    border-bottom: 1px solid var(--color-border);
}

.m-trade summary {
    font-weight: 700;
    font-family: var(--font-heading);
    font-size: 1.05rem;
    color: var(--color-ink);
    cursor: pointer;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
    min-height: 52px;
    outline: none;
}

.m-trade summary::-webkit-details-marker {
    display: none;
}

.m-trade summary::after {
    content: "▾";
    font-size: 1.25rem;
    color: var(--color-muted);
    transition: transform 0.2s ease;
    transform: rotate(0deg);
}

.m-trade[open] summary::after {
    transform: rotate(180deg);
    color: var(--color-accent);
}

.m-trade-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem 1rem;
}

.m-tool {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    padding: 0.5rem 0;
    font-size: 0.95rem;
    color: var(--color-ink) !important;
    text-decoration: none;
    min-height: 44px;
    justify-content: center;
}

.m-tool:active {
    color: var(--color-accent) !important;
}

.m-variants-row {
    font-size: 0.8rem;
    color: var(--color-muted);
    padding-left: 0.5rem;
    line-height: 1.4;
}

.m-variants-row a {
    color: var(--color-muted);
    text-decoration: none;
}

.m-variants-row a:active {
    color: var(--color-accent);
}

.m-secondary {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1rem;
    border-top: 1px solid var(--color-border);
    padding-top: 1.5rem;
}

.m-secondary-link {
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--color-ink) !important;
    text-decoration: none;
    min-height: 44px;
    display: flex;
    align-items: center;
}

.m-secondary-link:active {
    color: var(--color-accent) !important;
}

.m-metric {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 1rem;
    border-top: 1px solid var(--color-border);
    padding-top: 1.5rem;
    padding-bottom: 2rem;
}

.m-metric-label {
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--color-ink);
}

/* Main Content Area */
main {
    flex: 1;
}

/* Hero Section */
.hero {
    background-color: var(--color-bg-card);
    padding: 3.5rem 1.5rem;
    border-bottom: 1px solid var(--color-border);
}

.hero-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.hero-content {
    flex: 1;
    width: 100%;
}

.hero-home .hero-content {
    text-align: left;
}

.hero-home .stat-chips {
    justify-content: flex-start;
}

.hero-home p {
    margin-left: 0;
}

.hero-home .search-wrapper {
    margin-left: 0;
    padding-left: 0;
}

@media (min-width: 820px) {
    .hero-home .hero-inner {
        display: grid;
        grid-template-columns: 1fr auto;
        align-items: center;
        gap: 2.5rem;
    }
}

.hero-illustration-container {
    display: flex;
    justify-content: center;
    align-items: center;
    flex-shrink: 0;
}

.hero-illustration {
    max-width: min(360px, 100%);
    height: auto;
    display: block;
    object-fit: contain;
}

.hero h1 {
    font-size: 3rem;
    letter-spacing: -0.03em;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--color-ink) 60%, var(--color-accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    font-size: 1.15rem;
    color: var(--color-muted);
    max-width: 600px;
    margin: 0 auto 2rem;
}

.stat-chips {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.stat-chip {
    background-color: var(--color-bg-main);
    border: 1px solid var(--color-border);
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-muted);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.stat-chip .dot {
    width: 6px;
    height: 6px;
    background-color: var(--color-accent);
    border-radius: 50%;
}

/* Search container & components */
.search-wrapper {
    max-width: 650px;
    margin: -1.75rem auto 3rem;
    padding: 0 1.5rem;
    position: relative;
    z-index: 10;
}

.search-box-container {
    background-color: var(--color-bg-card);
    border: 2px solid var(--color-accent);
    border-radius: var(--radius-md);
    padding: 0.5rem;
    display: flex;
    align-items: center;
    box-shadow: var(--shadow-lg);
}

.search-input {
    flex: 1;
    border: none;
    outline: none;
    padding: 0.75rem 1rem;
    font-size: 1.1rem;
    font-family: var(--font-body);
    width: 100%;
}

.search-btn {
    background-color: var(--color-accent);
    color: white;
    border: none;
    border-radius: 8px;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.search-btn:hover {
    background-color: var(--color-accent-hover);
}

.search-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 0.75rem;
    justify-content: center;
}

.filter-btn {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    color: var(--color-muted);
    padding: 0.35rem 1rem;
    border-radius: 9999px;
    font-size: 0.85rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

.filter-btn.active {
    background-color: var(--color-accent);
    border-color: var(--color-accent);
    color: white;
}

.search-results-panel {
    display: none;
    margin-top: 0.5rem;
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    max-height: 400px;
    overflow-y: auto;
    position: absolute;
    left: 1.5rem;
    right: 1.5rem;
    z-index: 20;
}

.search-result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 1.25rem;
    border-bottom: 1px solid var(--color-border);
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
}

.search-result-item:hover {
    background-color: var(--color-bg-main);
}

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

.result-info {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    text-align: left;
}

.result-title-row {
    display: flex;
    align-items: center;
    gap: 0.50rem;
    flex-wrap: wrap;
}

.result-code {
    font-family: var(--font-heading);
    font-weight: 700;
    color: var(--color-ink);
    font-size: 1rem;
}

.result-title {
    color: var(--color-muted);
    font-size: 0.95rem;
    font-weight: 500;
}

.result-badge {
    font-size: 0.7rem;
    text-transform: uppercase;
    font-weight: 700;
    padding: 0.15rem 0.4rem;
    border-radius: 4px;
    letter-spacing: 0.05em;
}

.result-badge.naics {
    background-color: #E0E7FF;
    color: var(--color-accent);
}

.result-badge.sic {
    background-color: #FEF3C7;
    color: #D97706;
}

.result-sector {
    font-size: 0.75rem;
    color: #64748B;
}

.search-state-msg {
    padding: 2rem;
    text-align: center;
    color: var(--color-muted);
    font-weight: 500;
}

/* Sections */
.section {
    max-width: 1200px;
    margin: 0 auto 4rem;
    padding: 0 1.5rem;
}

.section-header {
    margin-bottom: 2rem;
}

.section-header h2 {
    font-size: 1.75rem;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--color-muted);
    font-size: 1rem;
}

/* Visual Decode Visual Component */
.decode-container {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
}

.decode-heading {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--color-border);
    padding-bottom: 1rem;
    margin-bottom: 1.5rem;
}

.decode-heading-title {
    font-weight: 700;
    font-size: 1.15rem;
}

.decode-code-tag {
    background-color: var(--color-accent-light);
    padding: 0.35rem 0.75rem;
    border-radius: 6px;
    font-weight: 700;
    font-family: var(--font-heading);
}

.decode-tiles {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 1rem;
}

.decode-tile {
    background-color: var(--color-bg-main);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 1.25rem 1rem;
    text-align: center;
    transition: var(--transition);
}

.decode-tile:hover {
    border-color: var(--color-accent);
    transform: translateY(-2px);
}

.tile-level {
    font-size: 0.7rem;
    font-weight: 700;
    color: #64748B;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.5rem;
}

.tile-digits {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-accent);
    margin-bottom: 0.5rem;
}

.tile-title {
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-ink);
    line-height: 1.3;
}

/* Validator Page & Layout */
.validator-grid {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    max-width: 1200px;
    margin: 2rem auto 4rem;
    padding: 0 1.5rem;
}

.validator-sidebar {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    align-self: start;
    box-shadow: var(--shadow-sm);
}

.validator-nav-btn {
    background: none;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    padding: 0.75rem 1rem;
    text-align: left;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--color-muted);
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.validator-nav-btn:hover {
    background-color: var(--color-bg-main);
    color: var(--color-ink);
}

.validator-nav-btn.active {
    background-color: var(--color-accent-light);
    border-color: var(--color-border);
    color: var(--color-accent);
}

.validator-nav-btn::after {
    content: "→";
    opacity: 0.5;
}

.validator-card {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 2.5rem;
    box-shadow: var(--shadow-md);
}

.validator-title {
    margin-bottom: 0.5rem;
}

.validator-desc {
    color: var(--color-muted);
    margin-bottom: 2rem;
    font-size: 0.95rem;
}

.validator-form {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    max-width: 550px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--color-ink);
}

.validator-input-group {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.validator-input {
    flex: 1;
    min-width: 0;
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 0.75rem 1rem;
    font-size: 1rem;
    font-family: var(--font-body);
    outline: none;
    transition: var(--transition);
}

.validator-input:focus {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

.validator-submit-btn {
    background-color: var(--color-accent);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    padding: 0.75rem 1.5rem;
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: var(--transition);
}

.validator-submit-btn:hover {
    background-color: var(--color-accent-hover);
}

.validator-result {
    margin-top: 1.5rem;
    border-radius: var(--radius-md);
    padding: 1.25rem;
    display: none;
    font-size: 0.95rem;
}

.validator-result.valid {
    display: block;
    background-color: var(--color-success-bg);
    border: 1px solid #A7F3D0;
    color: var(--color-success);
}

.validator-result.invalid {
    display: block;
    background-color: var(--color-error-bg);
    border: 1px solid #FECACA;
    color: var(--color-error);
}

.result-status {
    font-weight: 700;
    font-family: var(--font-heading);
    margin-bottom: 0.25rem;
}

.result-details {
    font-size: 0.9rem;
}

.result-link {
    margin-top: 0.75rem;
    display: inline-block;
    font-weight: 600;
    text-decoration: underline;
}

/* Home Section Layout */
.home-features {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.feature-card {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

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

.feature-icon {
    font-size: 2rem;
    margin-bottom: 1.25rem;
    color: var(--color-accent);
}

.feature-card h3 {
    margin-bottom: 0.75rem;
}

.feature-card p {
    color: var(--color-muted);
    font-size: 0.95rem;
    margin-bottom: 1.25rem;
}

/* Footer Section */
footer {
    background-color: var(--color-ink);
    color: #94A3B8; /* Slate 400 */
    border-top: 1px solid #1E293B;
    padding: 4rem 1.5rem;
    font-size: 0.9rem;
}

.footer-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 3rem;
}

.footer-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-brand {
    max-width: 350px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-family: var(--font-heading);
    font-weight: 800;
    font-size: 1.25rem;
    color: white;
    margin-bottom: 1rem;
}

.footer-logo-badge {
    background-color: var(--color-accent);
    color: white;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    font-weight: 800;
}

.footer-brand p {
    line-height: 1.5;
}

.footer-links-grid {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 2.5rem 2rem;
    width: 100%;
}

.footer-link-col {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.footer-link-col h3 {
    color: white;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 0.5rem;
}

.footer-link-col a {
    color: #94A3B8;
}

.footer-link-col a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid #1E293B;
    padding-top: 2rem;
    text-align: center;
}

.footer-disclaimer {
    max-width: 800px;
    margin: 0 auto 1.5rem;
    font-size: 0.8rem;
    line-height: 1.6;
}

.footer-copy {
    font-size: 0.8rem;
}

/* Accessibility Utilities */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-accent);
    color: white;
    padding: 8px;
    z-index: 100;
    transition: top 0.2s;
}

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

/* Media Queries (Responsive Design) */
@media (max-width: 991px) {
    .validator-grid {
        grid-template-columns: minmax(0, 1fr);
    }
    
    .home-features {
        grid-template-columns: minmax(0, 1fr);
    }
    
    .decode-tiles {
        grid-template-columns: minmax(0, 1fr);
    }
    
    .footer-links-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
    }
}

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }
    
    .nav-desktop {
        display: none;
    }
    
    .mobile-nav-toggle {
        display: block;
    }
    
    .hero h1 {
        font-size: 2.25rem;
    }
    
    .footer-top {
        flex-direction: column;
        gap: 3rem;
    }
    
    .footer-links-grid {
        grid-template-columns: minmax(0, 1fr);
        gap: 2rem;
    }
}

/* FAQ Accordion Styling (obdii collapsible details style) */
.faq-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-top: 1.5rem;
}

.faq-item {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--transition);
}

.faq-item:hover {
    border-color: var(--color-accent);
}

.faq-item summary {
    padding: 1.25rem 1.5rem;
    font-weight: 700;
    font-family: var(--font-heading);
    font-size: 1.05rem;
    color: var(--color-ink);
    cursor: pointer;
    list-style: none; /* Hide default browser marker */
    display: flex;
    justify-content: space-between;
    align-items: center;
    outline: none;
    transition: var(--transition);
}

.faq-item summary::-webkit-details-marker {
    display: none; /* Webkit browser marker hide */
}

/* Custom chevron rotation using pseudo-element */
.faq-item summary::after {
    content: "▾";
    font-size: 1.25rem;
    color: var(--color-muted);
    transition: transform 0.2s ease;
    transform: rotate(0deg);
}

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

.faq-item summary:hover {
    color: var(--color-accent);
}

.faq-answer {
    padding: 0 1.5rem 1.25rem;
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--color-muted);
    border-top: 1px solid transparent;
}

.faq-item[open] .faq-answer {
    border-top-color: var(--color-border);
}

/* Pill / Chip Link List for Related Diagnostic Codes / Related Calculators */
.pill-grid {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
    margin-top: 1rem;
}

.pill-chip {
    background-color: var(--color-bg-card);
    border: 1px solid var(--color-border);
    color: var(--color-ink);
    padding: 0.6rem 1.2rem;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    box-shadow: var(--shadow-sm);
}

.pill-chip:hover {
    background-color: var(--color-accent-light);
    border-color: var(--color-accent);
    color: var(--color-accent);
    transform: translateY(-1px);
}

/* ==========================================
   DESIGN SYSTEM UPGRADES (DESIGN.md & NAV_AND_POLISH_SPEC.md)
   ========================================== */

/* 1. Typography Display Adjustments */
h1 {
    letter-spacing: -0.02em;
}
h2 {
    letter-spacing: -0.015em;
}

/* 2. Numeric Alignment & Tabular Figures */
.tabular-nums,
[id^="out-"],
.result-value,
.metric-value,
.imperial-value,
table td,
.stat-chip,
.stat-chip span,
[id^="output-card"] strong,
[id^="output-card"] div[id^="out-"] {
    font-variant-numeric: tabular-nums;
    font-feature-settings: "tnum";
}

/* 3. Hero Atmospheric Gradient Wash & dot grid (NAV_AND_POLISH_SPEC §3a) */
.hero {
    position: relative;
    isolation: isolate;
    background:
      radial-gradient(55rem 26rem at 12% -12%, rgba(79,70,229,.13), transparent 68%),
      radial-gradient(46rem 24rem at 96% -6%, rgba(99,102,241,.10), transparent 62%),
      var(--color-bg-main);
}
.hero::after {
    content: "";
    position: absolute;
    inset: 0;
    z-index: -1;
    opacity: .5;
    background-image: radial-gradient(rgba(15,23,42,.05) 1px, transparent 1px);
    background-size: 22px 22px;
    -webkit-mask-image: linear-gradient(180deg, #000, transparent 70%);
    mask-image: linear-gradient(180deg, #000, transparent 70%);
}

/* 4. Soft blue-tinted elevation & card padding (L1 / L2) */
.validator-card, .decode-container {
    box-shadow: 0 1px 3px rgba(15,23,42,.06) !important;
    border-radius: 12px;
    padding: 32px !important; /* Standard 32px card padding */
}

/* 5. Pill CTAs (Pills-only button rules) */
.search-btn, 
.validator-submit-btn, 
.btn, 
.cta-btn, 
button[type="submit"], 
.nav-cta {
    border-radius: 9999px !important; /* Pill style */
}

/* 6. Result Card Visual Hero (NAV_AND_POLISH_SPEC §3b) */
.output-card, #output-card {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: 16px;
    padding: 32px !important;
    box-shadow: 0 8px 24px rgba(15,23,42,.08), 0 2px 6px rgba(15,23,42,.04) !important;
    border-top: 3px solid var(--color-accent) !important; /* accent cap */
}
[id^="out-"].result-value, .result-value {
    font-family: var(--font-heading);
    font-weight: 800;
    letter-spacing: -.01em;
    font-size: clamp(2rem, 4.5vw, 2.75rem);
    line-height: 1.05;
    color: var(--color-ink);
    font-variant-numeric: tabular-nums;
    font-feature-settings: "tnum";
}
.result-unit {
    color: var(--color-muted);
    font-weight: 600;
    font-size: 1rem;
    margin-left: .35rem;
}

/* 7. Nav Trigger & Dropdown Menu Interactions (NAV_AND_POLISH_SPEC §1 & §2) */
.nav-dropdown {
    position: relative;
}
.nav-dropdown-trigger {
    display: inline-flex;
    align-items: center;
    gap: .5rem;
    background: var(--color-accent);
    color: #fff;
    font-family: var(--font-body);
    font-weight: 600;
    font-size: .95rem;
    line-height: 1;
    padding: .62rem 1.2rem;
    min-height: 42px;
    border: none;
    border-radius: 9999px;
    cursor: pointer;
    box-shadow: 0 1px 2px rgba(15,23,42,.10);
    transition: background .18s ease, transform .18s ease, box-shadow .18s ease;
}
.nav-dropdown-trigger:hover {
    background: var(--color-accent-hover);
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(79,70,229,.28);
}
.nav-dropdown-trigger:active {
    transform: translateY(0);
    box-shadow: 0 1px 2px rgba(15,23,42,.12);
}
.nav-dropdown-trigger:focus-visible {
    outline: none;
    box-shadow: 0 0 0 3px rgba(79,70,229,.38);
}
.nav-dropdown-trigger svg {
    width: 13px;
    height: 13px;
    transition: transform .2s ease;
}
.nav-dropdown.open .nav-dropdown-trigger {
    background: var(--color-accent-hover);
}
.nav-dropdown.open .nav-dropdown-trigger svg {
    transform: rotate(180deg); /* chevron flips when open */
}
@media (prefers-reduced-motion: reduce) {
    .nav-dropdown-trigger {
        transition: none;
    }
    .nav-dropdown-trigger:hover {
        transform: none;
    }
}

.nav-dropdown-content {
    position: absolute;
    top: calc(100% + 10px);
    left: 50%;
    transform: translateX(-50%) translateY(-6px);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    z-index: 200;
    transition: opacity .16s ease, transform .16s ease, visibility 0s linear .16s;
    
    /* grid layout details */
    display: grid;
    grid-template-columns: repeat(4, minmax(190px, 1fr));
    gap: 1.5rem 2rem;
    padding: 1.75rem 2rem;
    width: min(1040px, 94vw);
    max-width: 1040px;
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    text-align: left;
}
.nav-dropdown.open .nav-dropdown-content {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
    transition: opacity .18s ease, transform .18s ease;
}
/* transparent hover-bridge so cursor never crosses dead space */
.nav-dropdown-content::before {
    content: "";
    position: absolute;
    top: -10px;
    left: 0;
    right: 0;
    height: 10px;
}
@media (prefers-reduced-motion: reduce) {
    .nav-dropdown-content,
    .nav-dropdown.open .nav-dropdown-content {
        transition: none;
        transform: translateX(-50%);
    }
}

.nav-dropdown-section {
    display: flex;
    flex-direction: column;
    gap: .15rem;
    align-content: start;
}
.nav-dropdown-title {
    font-size: .72rem;
    font-weight: 700;
    letter-spacing: .06em;
    text-transform: uppercase;
    color: var(--color-accent);
    margin-bottom: .5rem;
    padding-bottom: .4rem;
    border-bottom: 1px solid var(--color-border);
    min-height: 2.1rem;
    display: flex;
    align-items: flex-end;
}
.nav-dropdown-title a {
    color: inherit;
    text-decoration: none;
}
.nav-dropdown-title a:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}
.nav-dropdown-link {
    display: block;
    font-size: .9rem;
    color: var(--color-ink) !important;
    padding: .28rem 0;
    line-height: 1.3;
    text-decoration: none;
}
.nav-dropdown-link:hover {
    color: var(--color-accent) !important;
    text-decoration: none;
}
.nav-variants {
    font-size: .76rem;
    color: var(--color-muted);
    padding: 0 0 .35rem .1rem;
    line-height: 1.35;
}
.nav-variants a {
    color: var(--color-muted);
    text-decoration: none;
}
.nav-variants a:hover {
    color: var(--color-accent);
    text-decoration: none;
}
.nav-viewall {
    margin-top: .5rem;
    font-size: .8rem;
    font-weight: 600;
    color: var(--color-accent);
    text-decoration: none;
}
.nav-viewall:hover {
    color: var(--color-accent-hover);
    text-decoration: underline;
}
@media (max-width: 991px) {
    .nav-dropdown-content {
        width: 480px;
        grid-template-columns: repeat(2, 1fr);
    }
}

/* ==========================================================================
   HOMEPAGE HERO ILLUSTRATION LAYOUT (HERO_ILLUSTRATION_SPEC.md & §4)
   ========================================================================= */
.hero-home {
    padding: 5rem 1.5rem 4rem !important;
}

.hero-home .hero-inner {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: 3rem;
    text-align: center;
}

.hero-home .hero-content {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.hero-home .hero-content h1 {
    font-size: clamp(1.8rem, 7vw, 3.25rem);
    line-height: 1.1;
    margin-bottom: 1rem;
    text-align: inherit;
}

.hero-home .hero-content p {
    font-size: 1.15rem;
    color: var(--color-muted);
    max-width: 600px;
    margin: 0 auto 2rem;
    text-align: inherit;
}

.hero-home .stat-chips {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.hero-home .search-wrapper {
    max-width: 500px;
    margin: 1.5rem auto 0;
    padding: 0;
    width: 100%;
}

.hero-home .search-filters {
    justify-content: center;
}

.hero-home .hero-illustration-container {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
}

.hero-home .hero-illustration {
    display: block;
    max-width: min(420px, 100%);
    height: auto;
    object-fit: contain;
    aspect-ratio: 640 / 810;
}

/* Tablet and Desktop media queries */
@media (min-width: 900px) {
    .hero-home .hero-inner {
        grid-template-columns: 1.15fr 0.85fr;
        gap: 48px;
        align-items: center;
        text-align: left;
    }
    
    .hero-home .hero-content {
        align-items: flex-start;
    }
    
    .hero-home .hero-content p {
        margin: 0 0 2rem 0;
    }
    
    .hero-home .stat-chips {
        justify-content: flex-start;
        margin-bottom: 1.25rem;
    }
    
    .hero-home .search-wrapper {
        max-width: 580px;
        margin: 1.5rem 0 0 0;
    }
    
    .hero-home .search-filters {
        justify-content: flex-start;
    }
}

@media (max-width: 899px) and (min-width: 768px) {
    .hero-home .hero-illustration {
        max-width: 320px;
    }
}

@media (max-width: 767px) {
    .hero-home {
        padding: 3.5rem 1.2rem 3rem !important;
    }
    .hero-home .hero-illustration-container,
    .hero-home .hero-illustration {
        display: none !important; /* hide on mobile to protect LCP */
    }
}

/* Responsive Table container to prevent horizontal overflow */
table {
    display: block;
    width: 100%;
    max-width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    box-sizing: border-box;
}

/* Calculator card constraints and inputs box-sizing (NAV_AND_POLISH_SPEC §5b) */
.validator-card, .decode-container, .output-card, #output-card, .validator-sidebar {
    box-sizing: border-box;
    max-width: 100%;
    width: 100%;
    min-width: 0;
}
.validator-sidebar input:not([type="checkbox"]):not([type="radio"]),
.validator-sidebar select,
.validator-sidebar textarea,
.validator-card input:not([type="checkbox"]):not([type="radio"]),
.validator-card select,
.validator-card textarea,
.decode-container input:not([type="checkbox"]):not([type="radio"]),
.decode-container select,
.decode-container textarea,
.validator-input {
    width: 100%;
    max-width: 100%;
    box-sizing: border-box;
}

@media (max-width: 768px) {
    .validator-card, .validator-sidebar, .decode-container, .output-card, #output-card {
        padding: 18px !important;
    }
    .validator-grid, .calculator-grid {
        grid-template-columns: minmax(0, 1fr) !important;
    }
    .validator-submit-btn, .btn, .cta-btn, button[type="submit"], .search-btn {
        width: 100% !important;
        box-sizing: border-box;
    }
}

/* Declarative Unit Toggle Rules */
.unit-metric {
    display: none;
}
.unit-imperial {
    display: inline;
}
html[data-units="metric"] .unit-imperial {
    display: none !important;
}
html[data-units="metric"] .unit-metric {
    display: inline !important;
}
html[data-units="imperial"] .unit-imperial {
    display: inline !important;
}
html[data-units="imperial"] .unit-metric {
    display: none !important;
}

/* Print Media Styles (A4/Letter Report) */
@media print {
    /* Hide menus, header, footer, sidebars, lead forms, CTAs, and other interactive elements */
    header, footer, .mobile-menu, .validator-sidebar, .lead-capture-form, 
    .cite-affordance, #moat-buttons-container, .mobile-nav-toggle, 
    .nav-desktop, .filter-btn, .pill-grid, .success-msg, .breadcrumb-nav {
        display: none !important;
    }

    /* Reset global layout */
    body, html, .app-container, main {
        background: #ffffff !important;
        color: #0f172a !important;
        padding: 0 !important;
        margin: 0 !important;
        width: 100% !important;
        max-width: 100% !important;
        box-shadow: none !important;
    }

    main {
        display: block !important;
    }

    /* Print Header (Branding) */
    .tool-header-container {
        border-bottom: 2px solid #4f46e5 !important;
        background: #ffffff !important;
        padding: 1rem 0 !important;
        margin-bottom: 2rem !important;
    }

    /* Results card display */
    .validator-card, #output-card {
        border: 1px solid #cbd5e1 !important;
        background: #ffffff !important;
        box-shadow: none !important;
        padding: 2rem !important;
        width: 100% !important;
        max-width: 100% !important;
        page-break-inside: avoid;
    }

    .result-value {
        color: #4f46e5 !important;
        font-weight: bold !important;
    }

    /* Keep table legible */
    table {
        border-collapse: collapse !important;
        width: 100% !important;
        margin-top: 1rem !important;
        page-break-inside: avoid;
    }

    th, td {
        border: 1px solid #cbd5e1 !important;
        padding: 0.5rem 1rem !important;
    }

    /* Ensure links look clean */
    a {
        text-decoration: underline !important;
        color: #0f172a !important;
    }
}

.blueprint-panel {
    padding: 1rem !important;
    box-sizing: border-box !important;
}

.bc-header-search-input {
    width: 100%;
    padding: 0.35rem 0.6rem 0.35rem 1.9rem;
    font-size: 0.8rem;
    border-radius: 0.375rem;
    border: 1px solid var(--color-border);
    background-color: var(--color-bg-card);
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748B' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Ccircle cx='11' cy='11' r='8'/%3E%3Cline x1='21' y1='21' x2='16.65' y2='16.65'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: 0.5rem center;
    color: var(--color-ink);
}