/**
 * Exam-Study.in - Unified Design System & Responsive Stylesheet
 * Standardized layout, color palette, typography, top menu, sidebars, and SEO-friendly mobile styling
 */

:root {
    /* Brand Color Palette - Professional, Trustworthy & High Contrast */
    --primary: #1e40af;         /* Royal Navy Blue */
    --primary-dark: #1e3a8a;    /* Deep Blue for Hover/Active */
    --primary-light: #eff6ff;   /* Soft Tint for Backgrounds & Hover */
    --primary-border: #bfdbfe;  /* Subtle primary border */

    --accent: #f59e0b;          /* High-converting Amber/Gold */
    --accent-dark: #d97706;     /* Deep Gold for Hover */
    --accent-light: #fef3c7;    /* Soft Amber Tint */

    --success: #059669;         /* Verified / Success Green */
    --success-light: #ecfdf5;
    --danger: #dc2626;
    --danger-light: #fef2f2;
    --info: #0284c7;
    --info-light: #f0f9ff;

    /* Neutrals */
    --bg-main: #f8fafc;         /* Crisp Slate 50 background */
    --bg-surface: #ffffff;      /* Pure White Card/Container */
    --text-main: #0f172a;       /* Deep Slate 900 for sharp reading */
    --text-muted: #475569;      /* Slate 600 */
    --text-light: #64748b;      /* Slate 500 */
    --border: #e2e8f0;          /* Slate 200 border */
    --border-dark: #cbd5e1;

    /* Radii & Shadows */
    --radius-sm: 6px;
    --radius: 10px;
    --radius-lg: 16px;
    --radius-pill: 9999px;

    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 20px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
    /* Indic Font Fallback Stack with Windows (Nirmala UI, Mangal), Apple (Kohinoor), and Google fallbacks */
    --font-indic: "Noto Sans Devanagari", "Nirmala UI", "Mangal", "Kohinoor Devanagari", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* ==========================================================================
   1. Base & Global Reset
   ========================================================================== */
html {
    box-sizing: border-box;
    scroll-behavior: smooth;
    font-size: 16px;
}

*, *:before, *:after {
    box-sizing: inherit;
}

body {
    margin: 0 !important;
    padding: 0 !important;
    background-color: var(--bg-main) !important;
    color: var(--text-main) !important;
    font-family: var(--font-indic) !important;
    font-size: 1rem;
    line-height: 1.75 !important;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    -webkit-font-feature-settings: "kern" 1, "liga" 1;
    font-feature-settings: "kern" 1, "liga" 1;
    overflow-x: hidden;
}

/* Force all UI elements, controls, tables, and typography to inherit the Indic font */
html, button, input, select, textarea,
h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6,
table, table th, table td,
.topic-hero, .topic-hero h1, .topic-content, .chapter-title,
.offcanvas, .navbar, .breadcrumb, .card {
    font-family: var(--font-indic) !important;
    text-rendering: optimizeLegibility;
    -webkit-font-feature-settings: "kern" 1, "liga" 1;
    font-feature-settings: "kern" 1, "liga" 1;
}

img, video, svg, iframe {
    max-width: 100%;
    height: auto;
}

a {
    color: var(--primary);
    text-decoration: none;
    transition: color 0.15s ease, background-color 0.15s ease;
}

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

/* ==========================================================================
   2. Typography Hierarchy (Standardized Font Sizes)
   ========================================================================== */
h1, .h1 {
    font-size: clamp(1.75rem, 3.5vw, 2.35rem) !important;
    font-weight: 800 !important;
    line-height: 1.35 !important;
    color: var(--text-main);
    margin-top: 0;
    margin-bottom: 0.85rem;
    letter-spacing: -0.3px;
}

h2, .h2 {
    font-size: clamp(1.35rem, 2.5vw, 1.75rem) !important;
    font-weight: 700 !important;
    line-height: 1.4 !important;
    color: var(--text-main);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

h3, .h3 {
    font-size: clamp(1.15rem, 2vw, 1.35rem) !important;
    font-weight: 700 !important;
    line-height: 1.45 !important;
    color: var(--text-main);
    margin-top: 1.25rem;
    margin-bottom: 0.5rem;
}

h4, .h4, h5, .h5, h6, .h6 {
    font-weight: 700 !important;
    color: var(--text-main);
    margin-bottom: 0.5rem;
}

p {
    margin-top: 0;
    margin-bottom: 1rem;
    font-size: 1rem;
    line-height: 1.75;
    color: var(--text-main);
}

strong, b {
    font-weight: 700;
    color: #020617;
}

ul, ol {
    padding-left: 1.4rem;
    margin-bottom: 1.25rem;
}

li {
    margin-bottom: 0.4rem;
    line-height: 1.7;
}

/* ==========================================================================
   3. Website Top Menu (Site Header & Navbar Standard)
   ========================================================================== */
header.site-header {
    background: #ffffff !important;
    border-bottom: 1px solid var(--border) !important;
    box-shadow: var(--shadow-sm) !important;
    position: sticky !important;
    top: 0 !important;
    z-index: 1040 !important;
    padding: 0 !important;
    margin: 0 !important;
    color: var(--text-main) !important;
    text-align: left !important;
}

header.site-header * {
    text-shadow: none !important;
}

.site-header .navbar {
    padding-top: 0.65rem;
    padding-bottom: 0.65rem;
}

.site-header .brand {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--primary) !important;
    letter-spacing: -0.5px;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    transition: opacity 0.2s ease;
}

.site-header .brand span {
    color: var(--accent) !important;
}

.site-header .navbar-nav {
    gap: 0.15rem;
}

.site-header .nav-link {
    font-size: 0.94rem !important;
    font-weight: 600 !important;
    color: #334155 !important;
    padding: 0.5rem 0.85rem !important;
    border-radius: var(--radius-sm);
    transition: all 0.2s ease !important;
}

.site-header .nav-link:hover,
.site-header .nav-link.active,
.site-header .show > .nav-link {
    color: var(--primary) !important;
    background-color: var(--primary-light) !important;
}

.site-header .dropdown-menu {
    border: 1px solid var(--border) !important;
    border-radius: var(--radius) !important;
    box-shadow: var(--shadow-lg) !important;
    padding: 8px !important;
    margin-top: 8px !important;
    background: #ffffff !important;
    animation: fadeInMenu 0.15s ease-out;
}

@keyframes fadeInMenu {
    from { opacity: 0; transform: translateY(-4px); }
    to { opacity: 1; transform: translateY(0); }
}

.site-header .dropdown-item {
    font-size: 0.92rem !important;
    font-weight: 500 !important;
    color: #334155 !important;
    padding: 7px 12px !important;
    border-radius: 6px !important;
    transition: all 0.15s ease !important;
}

.site-header .dropdown-item:hover,
.site-header .dropdown-item:focus {
    background-color: var(--primary-light) !important;
    color: var(--primary) !important;
}

.site-header .dropdown-divider {
    border-top-color: var(--border) !important;
    margin: 6px 0 !important;
}

.site-header .btn-warning {
    background-color: var(--accent) !important;
    border-color: var(--accent) !important;
    color: #0f172a !important;
    font-weight: 700 !important;
    border-radius: var(--radius-sm) !important;
    padding: 0.45rem 1rem !important;
    box-shadow: var(--shadow-sm);
}

.site-header .btn-warning:hover {
    background-color: var(--accent-dark) !important;
    border-color: var(--accent-dark) !important;
    color: #ffffff !important;
}

/* ==========================================================================
   4. Left Side Menu (Unified Sidebar Standard)
   ========================================================================== */
aside {
    min-width: 0;
}

.offcanvas-lg,
.offcanvas-md,
.sidebar,
.verbal-sidebar,
.police-sidebar,
.vanrakshak-sidebar {
    background: #ffffff !important;
    border: 1px solid var(--border) !important;
    border-radius: var(--radius) !important;
    box-shadow: var(--shadow-sm) !important;
    overflow: hidden;
}

/* Sticky sidebar on desktop screens */
@media (min-width: 992px) {
    aside .offcanvas-lg,
    aside .offcanvas-md,
    aside .sidebar,
    aside .verbal-sidebar,
    aside .police-sidebar,
    aside .vanrakshak-sidebar,
    .sticky-sidebar {
        position: sticky !important;
        top: 76px !important;
        max-height: calc(100vh - 90px) !important;
        overflow-y: auto !important;
        height: auto !important;
        transform: none !important;
        visibility: visible !important;
        border: 1px solid var(--border) !important;
    }
}

/* Sidebar scrollbar styling */
.sidebar-scroll,
aside .offcanvas-body,
aside .offcanvas-lg,
aside .offcanvas-md {
    scrollbar-width: thin;
    scrollbar-color: #cbd5e1 transparent;
}

.sidebar-scroll::-webkit-scrollbar,
aside .offcanvas-body::-webkit-scrollbar {
    width: 5px;
}

.sidebar-scroll::-webkit-scrollbar-thumb,
aside .offcanvas-body::-webkit-scrollbar-thumb {
    background-color: #cbd5e1;
    border-radius: 4px;
}

/* Unified sidebar navigation links */
aside nav a,
.sidebar a,
.verbal-side-link,
.police-side-link,
.offcanvas-body nav a {
    display: block !important;
    padding: 0.55rem 0.85rem !important;
    margin-bottom: 0.25rem !important;
    border-radius: var(--radius-sm) !important;
    font-size: 0.92rem !important;
    font-weight: 500 !important;
    color: #334155 !important;
    text-decoration: none !important;
    line-height: 1.5 !important;
    border: 1px solid transparent !important;
    transition: all 0.15s ease !important;
}

aside nav a:hover,
.sidebar a:hover,
.verbal-side-link:hover,
.police-side-link:hover,
.offcanvas-body nav a:hover,
.hover-bg-light:hover {
    background-color: var(--primary-light) !important;
    color: var(--primary) !important;
    border-color: var(--primary-border) !important;
}

aside nav a.active,
.sidebar a.active,
.verbal-side-link.active,
.police-side-link.active,
.offcanvas-body nav a.active,
aside nav a.bg-primary,
.offcanvas-body nav a.bg-primary {
    background-color: var(--primary) !important;
    color: #ffffff !important;
    font-weight: 700 !important;
    border-color: var(--primary) !important;
}

/* Mobile sidebar toggle button */
button[data-bs-toggle="offcanvas"],
.verbal-menu-btn,
.police-menu-btn {
    min-height: 44px;
    font-weight: 700;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
}

/* ==========================================================================
   5. Standardized Breadcrumbs & Hero Banners
   ========================================================================== */
.breadcrumb {
    background: transparent !important;
    padding: 0 !important;
    margin-bottom: 1.25rem !important;
    font-size: 0.9rem !important;
    font-weight: 500 !important;
}

.breadcrumb-item + .breadcrumb-item::before {
    content: "›" !important;
    font-size: 1.1rem;
    line-height: 1;
    color: var(--text-muted);
}

.breadcrumb-item a {
    color: var(--primary);
    font-weight: 600;
}

.breadcrumb-item.active {
    color: var(--text-muted) !important;
}

/* Universal Hero Section across subjects */
.hero,
.topic-hero,
.verbal-home-hero,
.eco-hero {
    background: linear-gradient(135deg, #1e40af 0%, #1d4ed8 50%, #2563eb 100%) !important;
    color: #ffffff !important;
    border-radius: var(--radius-lg) !important;
    padding: 36px 30px !important;
    margin-bottom: 24px !important;
    box-shadow: var(--shadow-sm) !important;
    text-align: left;
}

.hero h1,
.topic-hero h1,
.verbal-home-hero h1,
.eco-hero h1 {
    color: #ffffff !important;
    font-weight: 800 !important;
    font-size: clamp(1.65rem, 3.5vw, 2.35rem) !important;
    line-height: 1.3 !important;
    margin-bottom: 10px !important;
    text-shadow: none !important;
}

.hero p,
.topic-hero p,
.verbal-home-hero p,
.eco-hero p {
    color: #e0e7ff !important;
    font-size: 1.05rem !important;
    line-height: 1.8 !important;
    max-width: 850px !important;
    margin-bottom: 18px !important;
}

/* ==========================================================================
   6. Content Containers & Cards Standardization
   ========================================================================== */
.content,
.main-content,
.verbal-topic-content,
.topic-content,
.eco-notes-content {
    background: #ffffff !important;
    border: 1px solid var(--border) !important;
    border-radius: var(--radius-lg) !important;
    padding: 24px 28px !important;
    box-shadow: var(--shadow-sm) !important;
    color: var(--text-main);
}

/* Universal Card Design */
.exam-card,
.subject-card,
.topic-card,
.v-card,
.feature-card,
.hover-card {
    background: #ffffff !important;
    border: 1px solid var(--border) !important;
    border-radius: var(--radius) !important;
    padding: 20px !important;
    box-shadow: var(--shadow-sm) !important;
    transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease !important;
    height: 100%;
}

.exam-card:hover,
.subject-card:hover,
.topic-card:hover,
.v-card:hover,
.feature-card:hover,
.hover-card:hover {
    transform: translateY(-3px) !important;
    box-shadow: var(--shadow-lg) !important;
    border-color: var(--primary-border) !important;
}

/* Card Icons */
.card-icon,
.v-icon {
    width: 48px;
    height: 48px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border-radius: 12px;
    background: var(--primary-light);
    color: var(--primary);
    font-size: 1.4rem;
    font-weight: 800;
    margin-bottom: 12px;
}

/* ==========================================================================
   7. Tables & Responsive Data Presentation
   ========================================================================== */
table {
    width: 100% !important;
    max-width: 100% !important;
    margin-bottom: 1.5rem !important;
    border-collapse: separate !important;
    border-spacing: 0 !important;
    border: 1px solid var(--border) !important;
    border-radius: var(--radius-sm) !important;
    overflow: hidden !important;
    background: #ffffff !important;
}

table th {
    background-color: #f1f5f9 !important;
    color: var(--text-main) !important;
    font-weight: 700 !important;
    padding: 12px 14px !important;
    border-bottom: 2px solid var(--border) !important;
    border-right: 1px solid var(--border) !important;
    font-size: 0.93rem !important;
    text-align: left;
}

table td {
    padding: 10px 14px !important;
    border-bottom: 1px solid var(--border) !important;
    border-right: 1px solid var(--border) !important;
    color: var(--text-main) !important;
    font-size: 0.93rem !important;
    line-height: 1.6 !important;
}

table tr:last-child td {
    border-bottom: none !important;
}

table tr td:last-child,
table tr th:last-child {
    border-right: none !important;
}

table tr:nth-child(even) td {
    background-color: #f8fafc !important;
}

table tr:hover td {
    background-color: var(--primary-light) !important;
}

.table-responsive {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    margin-bottom: 1.5rem;
}

@media (max-width: 768px) {
    table:not(.fraction) {
        display: block !important;
        width: 100% !important;
        overflow-x: auto !important;
        -webkit-overflow-scrolling: touch !important;
    }
}

/* ==========================================================================
   8. Buttons, Badges & Interactive Controls
   ========================================================================== */
.btn {
    font-weight: 600 !important;
    border-radius: var(--radius-sm) !important;
    padding: 0.5rem 1.15rem !important;
    transition: all 0.15s ease !important;
}

.btn-primary {
    background-color: var(--primary) !important;
    border-color: var(--primary) !important;
    color: #ffffff !important;
}

.btn-primary:hover,
.btn-primary:focus {
    background-color: var(--primary-dark) !important;
    border-color: var(--primary-dark) !important;
}

.btn-outline-primary {
    color: var(--primary) !important;
    border-color: var(--primary) !important;
    background: transparent !important;
}

.btn-outline-primary:hover,
.btn-outline-primary:focus {
    background-color: var(--primary) !important;
    color: #ffffff !important;
}

.btn-warning {
    background-color: var(--accent) !important;
    border-color: var(--accent) !important;
    color: #0f172a !important;
}

.btn-warning:hover {
    background-color: var(--accent-dark) !important;
    border-color: var(--accent-dark) !important;
    color: #ffffff !important;
}

/* Badges */
.badge {
    font-weight: 600;
    padding: 0.4rem 0.75rem;
    border-radius: var(--radius-pill);
    font-size: 0.82rem;
}

.badge-soft {
    background-color: var(--primary-light) !important;
    color: var(--primary) !important;
}

/* ==========================================================================
   9. SEO & Core Web Vitals Optimization
   ========================================================================== */
/* Minimum touch target for links and buttons on mobile */
@media (max-width: 767.98px) {
    .btn,
    .site-header .nav-link,
    aside nav a {
        min-height: 44px;
        display: flex;
        align-items: center;
    }

    .hero,
    .topic-hero,
    .verbal-home-hero,
    .eco-hero {
        padding: 24px 18px !important;
        border-radius: 12px !important;
    }

    .content,
    .main-content,
    .verbal-topic-content,
    .topic-content,
    .eco-notes-content {
        padding: 16px !important;
        border-radius: 12px !important;
    }

    .site-header .navbar-collapse {
        background: #ffffff;
        padding: 14px;
        border-radius: var(--radius);
        margin-top: 8px;
        box-shadow: var(--shadow-lg);
        border: 1px solid var(--border);
    }
}

/* Universal Math Subject Components */
.topic-body .definition {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-left: 4px solid #2563eb;
    padding: 16px 20px;
    margin: 16px 0;
    border-radius: 8px;
}
.topic-body .formula {
    background: #eff6ff;
    border: 1px solid #bfdbfe;
    border-left: 4px solid #3b82f6;
    padding: 14px 18px;
    margin: 16px 0;
    border-radius: 8px;
    font-size: 1.05rem;
}
.topic-body .example {
    background: #f0fdf4;
    border: 1px solid #bbf7d0;
    border-left: 4px solid #16a34a;
    padding: 16px 20px;
    margin: 16px 0;
    border-radius: 8px;
}
.topic-body .question {
    background: #fffbeb;
    border: 1px solid #fef3c7;
    border-left: 4px solid #f59e0b;
    padding: 18px 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}
.topic-body .option {
    background: #f1f5f9;
    padding: 8px 12px;
    border-radius: 6px;
    margin: 4px 0;
    font-size: 0.95rem;
}
.topic-body .explanation {
    font-weight: 700;
    color: #b91c1c;
    margin-top: 10px;
}
.topic-body table {
    width: 100%;
    margin: 16px 0;
    border-collapse: collapse;
}
.topic-body table th,
.topic-body table td {
    padding: 10px 14px;
    border: 1px solid #cbd5e1;
}
.topic-body table th {
    background: #f8fafc;
    font-weight: 700;
}

/* ==========================================================================
   Math Formula & Fraction Component Styling (CSS Native Display)
   ========================================================================== */
.math-formula-box {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-left: 4px solid #2563eb;
    border-radius: 8px;
    padding: 12px 16px;
    margin: 10px 0;
    font-size: 1rem;
    line-height: 1.6;
}

.math-frac {
    display: inline-flex;
    flex-direction: column;
    vertical-align: middle;
    text-align: center;
    padding: 0 4px;
    font-size: 0.9em;
    line-height: 1.15;
    margin: 0 3px;
}

.math-frac .num {
    border-bottom: 2px solid currentColor;
    padding-bottom: 2px;
    display: block;
    font-weight: 700;
}

.math-frac .den {
    padding-top: 2px;
    display: block;
    font-weight: 700;
}

.math-eq-highlight {
    background: #eff6ff;
    color: #1e40af;
    padding: 6px 12px;
    border-radius: 6px;
    font-weight: 700;
    display: inline-block;
    border: 1px solid #bfdbfe;
    margin: 4px 0;
}

.math-rule-item {
    padding: 8px 0;
    border-bottom: 1px dashed #e2e8f0;
}
.math-rule-item:last-child {
    border-bottom: none;
}

/* Fraction table display fallback used in older topics */
table.fraction {
    display: inline-table;
    vertical-align: middle;
    text-align: center;
    border-collapse: collapse;
    margin: 2px 4px;
    border: none !important;
}
table.fraction td {
    padding: 2px 6px !important;
    border: none !important;
}
table.fraction td.upper_line {
    border-top: 2px solid #222 !important;
}