/* ==========================================================================
   AI Study Baseline - Technical Dashboard Stylesheet
   Modern layout, premium glassmorphism, responsive sidebar & theme switching.
   ========================================================================== */

/* --- Variables & Colors --- */
:root {
    /* Palette base - Light Mode (Clean Slate & Translucent Glass) */
    --bg-base: #f8fafc;
    --bg-surface: rgba(255, 255, 255, 0.7);
    --bg-surface-hover: rgba(255, 255, 255, 0.9);
    --bg-header: rgba(248, 250, 252, 0.8);
    --bg-card: rgba(255, 255, 255, 0.65);
    --bg-card-hover: #ffffff;
    --bg-btn: rgba(15, 23, 42, 0.03);
    --bg-btn-hover: rgba(var(--accent-color), 0.05);
    --bg-tabs: rgba(15, 23, 42, 0.02);
    --bg-tab-active: #ffffff;
    --bg-search: rgba(15, 23, 42, 0.03);
    --bg-search-focus: #ffffff;
    --bg-footer: rgba(255, 255, 255, 0.4);
    --bg-banner: linear-gradient(135deg, #4f46e5 0%, #6366f1 50%, #818cf8 100%);
    --bg-banner-visual: rgba(255, 255, 255, 0.15);
    
    --text-primary: #0f172a;
    --text-secondary: #334155;
    --text-muted: #64748b;
    --text-banner: #ffffff;
    
    --border-glow: rgba(15, 23, 42, 0.05);
    --border-hover: rgba(15, 23, 42, 0.1);
    --border-card: rgba(15, 23, 42, 0.04);
    --border-card-hover: rgba(var(--accent-color), 0.2);
    --border-btn: rgba(15, 23, 42, 0.05);
    --border-search: rgba(15, 23, 42, 0.06);
    
    --shadow-main: 0 10px 30px -10px rgba(15, 23, 42, 0.04);
    --shadow-glow: 0 10px 25px -10px rgba(var(--accent-color), 0.15);
    --shadow-card-hover: 0 16px 36px -12px rgba(15, 23, 42, 0.08);
    
    --logo-grad-start: #0f172a;
    --logo-grad-end: #4f46e5;
    
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --font-display: 'Outfit', system-ui, -apple-system, sans-serif;
    
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-theme {
    /* Palette base - Dark Mode (Deep Nebula Space) */
    --bg-base: #080b11;
    --bg-surface: rgba(15, 22, 36, 0.75);
    --bg-surface-hover: rgba(22, 32, 53, 0.9);
    --bg-header: rgba(8, 11, 17, 0.85);
    --bg-card: rgba(18, 26, 44, 0.6);
    --bg-card-hover: #121a2c;
    --bg-btn: rgba(255, 255, 255, 0.03);
    --bg-btn-hover: rgba(var(--accent-color), 0.15);
    --bg-tabs: rgba(255, 255, 255, 0.02);
    --bg-tab-active: #121a2c;
    --bg-search: rgba(255, 255, 255, 0.03);
    --bg-search-focus: #121a2c;
    --bg-footer: rgba(18, 26, 44, 0.45);
    --bg-banner: linear-gradient(135deg, #1e1b4b 0%, #311042 50%, #082f49 100%);
    --bg-banner-visual: rgba(255, 255, 255, 0.05);
    
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --text-banner: #f8fafc;
    
    --border-glow: rgba(255, 255, 255, 0.04);
    --border-hover: rgba(255, 255, 255, 0.12);
    --border-card: rgba(255, 255, 255, 0.05);
    --border-card-hover: rgba(var(--accent-color), 0.45);
    --border-btn: rgba(255, 255, 255, 0.06);
    --border-search: rgba(255, 255, 255, 0.08);
    
    --shadow-main: 0 12px 40px -15px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 10px 30px -10px rgba(var(--accent-color), 0.35);
    --shadow-card-hover: 0 20px 40px -15px rgba(0, 0, 0, 0.55), 0 0 16px -2px rgba(var(--accent-color), 0.2);
    
    --logo-grad-start: #f8fafc;
    --logo-grad-end: #818cf8;
}

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

html {
    scroll-behavior: smooth;
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    overflow-x: hidden;
    position: relative;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* --- Smooth Custom Scrollbar --- */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-base);
}
::-webkit-scrollbar-thumb {
    background: rgba(15, 23, 42, 0.12);
    border-radius: 6px;
    border: 2px solid var(--bg-base);
}
body.dark-theme ::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.12);
    border: 2px solid var(--bg-base);
}
::-webkit-scrollbar-thumb:hover {
    background: rgba(15, 23, 42, 0.25);
}
body.dark-theme ::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.25);
}

/* --- App Layout --- */
.app-layout {
    display: flex;
    min-height: 100vh;
    width: 100vw;
}

/* --- App Sidebar --- */
.app-sidebar {
    width: 280px;
    background: var(--bg-surface);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border-right: 1px solid var(--border-glow);
    padding: 2rem 1.25rem;
    display: flex;
    flex-direction: column;
    gap: 2rem;
    position: sticky;
    top: 0;
    height: 100vh;
    z-index: 100;
    transition: transform var(--transition-normal), background-color var(--transition-normal), border-color var(--transition-normal);
}

.sidebar-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    transition: transform var(--transition-fast) ease, opacity var(--transition-fast) ease;
    user-select: none;
}

.logo-area:hover {
    transform: translateY(-1px);
    opacity: 0.9;
}

.logo-area:active {
    transform: translateY(1px);
    opacity: 0.8;
}

.logo-icon {
    font-size: 2rem;
    filter: drop-shadow(0 0 10px rgba(99, 102, 241, 0.25));
    animation: pulse 3s infinite ease-in-out;
}

.logo-text {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.logo-text h1 {
    font-family: var(--font-display);
    font-size: 1.25rem;
    font-weight: 850;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--logo-grad-start) 30%, var(--logo-grad-end) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    line-height: 1.1;
    transition: background-color var(--transition-normal);
}

.logo-badge {
    display: inline-block;
    font-size: 0.6rem;
    font-weight: 700;
    color: #4f46e5;
    background: rgba(99, 102, 241, 0.1);
    padding: 0.1rem 0.35rem;
    border-radius: 4px;
    margin-top: 0.15rem;
}

body.dark-theme .logo-badge {
    color: #818cf8;
    background: rgba(129, 140, 248, 0.15);
}

/* --- Stats Widget in Sidebar --- */
.sidebar-stats {
    background: var(--bg-btn);
    border: 1px solid var(--border-glow);
    border-radius: 14px;
    padding: 0.85rem 1.15rem;
}

.stats-card {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.stats-label {
    font-size: 0.775rem;
    font-weight: 600;
    color: var(--text-secondary);
    font-family: var(--font-display);
    letter-spacing: -0.01em;
}

.stats-val {
    font-family: var(--font-display);
    font-size: 1.35rem;
    font-weight: 850;
    color: #4f46e5;
    text-shadow: 0 0 10px rgba(99, 102, 241, 0.1);
}

body.dark-theme .stats-val {
    color: #818cf8;
    text-shadow: 0 0 15px rgba(129, 140, 248, 0.25);
}

/* --- Sidebar Navigation --- */
.sidebar-nav {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    overflow-y: auto;
    scrollbar-width: none;
}

.sidebar-nav::-webkit-scrollbar {
    display: none;
}

.nav-title {
    font-size: 0.725rem;
    font-weight: 750;
    color: var(--text-muted);
    letter-spacing: 0.08em;
    text-transform: uppercase;
    margin-bottom: 0.35rem;
    font-family: var(--font-display);
}

.modules-list {
    display: flex;
    flex-direction: column;
    gap: 0.45rem;
}

.nav-item {
    background: transparent;
    border: 1px solid transparent;
    border-radius: 12px;
    padding: 0.75rem 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    cursor: pointer;
    color: var(--text-secondary);
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 0.875rem;
    transition: all var(--transition-normal);
    text-align: left;
    width: 100%;
    outline: none;
}

.nav-icon {
    font-size: 1.25rem;
    transition: transform var(--transition-normal);
    flex-shrink: 0;
}

.nav-text {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.nav-badge {
    font-size: 0.7rem;
    font-weight: 700;
    background: rgba(15, 23, 42, 0.05);
    color: var(--text-muted);
    padding: 0.15rem 0.45rem;
    border-radius: 20px;
    transition: all var(--transition-normal);
}

body.dark-theme .nav-badge {
    background: rgba(255, 255, 255, 0.06);
}

.nav-item:hover {
    background: rgba(var(--accent-color), 0.05);
    border-color: rgba(var(--accent-color), 0.15);
    color: var(--text-primary);
}

.nav-item:hover .nav-icon {
    transform: scale(1.15) rotate(4deg);
}

.nav-item.active {
    background: var(--bg-tab-active);
    border-color: rgba(var(--accent-color), 0.25);
    color: var(--text-primary);
    box-shadow: 0 8px 20px -8px rgba(var(--accent-color), 0.2), 0 2px 4px -1px rgba(0, 0, 0, 0.02);
}

body.dark-theme .nav-item.active {
    border-color: rgba(var(--accent-color), 0.45);
    box-shadow: 0 10px 24px -10px rgba(var(--accent-color), 0.35);
}

.nav-item.active .nav-badge {
    background: rgba(var(--accent-color), 0.12);
    color: rgb(var(--accent-color));
}

/* --- Sidebar Footer --- */
.sidebar-footer {
    border-top: 1px solid var(--border-glow);
    padding-top: 1.25rem;
}

.sidebar-footer .theme-toggle-btn {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 0.75rem;
    padding: 0.75rem 0.85rem;
    border-radius: 12px;
    background: var(--bg-btn);
    border: 1px solid var(--border-btn);
    cursor: pointer;
    color: var(--text-primary);
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 0.875rem;
    transition: all var(--transition-normal);
    outline: none;
}

.sidebar-footer .theme-toggle-btn .toggle-text {
    font-size: 0.85rem;
}

.sidebar-footer .theme-toggle-btn:hover {
    background: rgba(99, 102, 241, 0.08);
    border-color: rgba(99, 102, 241, 0.2);
    color: #4f46e5;
}

body.dark-theme .sidebar-footer .theme-toggle-btn:hover {
    background: rgba(129, 140, 248, 0.12);
    border-color: rgba(129, 140, 248, 0.25);
    color: #818cf8;
}

/* --- Main Viewport Area --- */
.main-viewport {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    height: 100vh;
    overflow-y: auto;
    position: relative;
    background-color: var(--bg-base);
}

.app-header {
    background: var(--bg-header);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-glow);
    padding: 1.15rem 3rem;
    position: sticky;
    top: 0;
    z-index: 90;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    min-height: 75px;
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.search-container {
    width: 100%;
    max-width: 480px;
}

.search-box {
    position: relative;
    width: 100%;
}

.search-icon {
    position: absolute;
    left: 1.15rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    font-size: 0.95rem;
    pointer-events: none;
    transition: color var(--transition-fast);
}

.search-box input[type="search"] {
    width: 100%;
    padding: 0.75rem 1.15rem 0.75rem 2.85rem;
    background: var(--bg-search);
    border: 1px solid var(--border-search);
    border-radius: 12px;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.925rem;
    outline: none;
    transition: all var(--transition-normal);
}

.search-box input[type="search"]::placeholder {
    color: var(--text-muted);
}

.search-box input[type="search"]:focus {
    background: var(--bg-search-focus);
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.08), 0 4px 20px rgba(15, 23, 42, 0.04);
}

.search-box input[type="search"]:focus + .search-icon {
    color: #4f46e5;
}

body.dark-theme .search-box input[type="search"]:focus {
    border-color: rgba(129, 140, 248, 0.4);
    box-shadow: 0 0 0 4px rgba(129, 140, 248, 0.12), 0 4px 20px rgba(0, 0, 0, 0.4);
}

body.dark-theme .search-box input[type="search"]:focus + .search-icon {
    color: #818cf8;
}

.mobile-menu-toggle {
    display: none;
    background: var(--bg-btn);
    border: 1px solid var(--border-btn);
    width: 44px;
    height: 44px;
    border-radius: 10px;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-primary);
    font-size: 1.25rem;
    outline: none;
    transition: all var(--transition-normal);
}

/* --- Main Content & Dashboard Elements --- */
.main-content {
    flex: 1;
    padding: 3rem;
    max-width: 1400px;
    width: 100%;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 2.25rem;
}

/* --- Dashboard Welcome Banner --- */
.dashboard-banner {
    background: var(--bg-banner);
    border-radius: 20px;
    padding: 2.5rem 3rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-banner);
    box-shadow: 0 10px 30px -10px rgba(79, 70, 229, 0.2);
    position: relative;
    overflow: hidden;
    margin-bottom: 0.5rem;
    border: 1px solid var(--border-glow);
}

.banner-content {
    max-width: 600px;
    z-index: 2;
}

.dashboard-banner h2 {
    font-family: var(--font-display);
    font-size: 1.85rem;
    font-weight: 850;
    letter-spacing: -0.02em;
    margin-bottom: 0.5rem;
    line-height: 1.2;
}

.banner-subtitle {
    font-size: 0.975rem;
    opacity: 0.9;
    line-height: 1.5;
}

.banner-visual {
    font-size: 5rem;
    opacity: 0.25;
    user-select: none;
    z-index: 1;
    animation: float 4s infinite ease-in-out;
}

@keyframes float {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    50% { transform: translateY(-10px) rotate(3deg); }
}

/* --- Grid Container --- */
.modules-grid {
    display: flex;
    flex-direction: column;
    width: 100%;
}

.module-block {
    display: none;
    animation: tabReveal var(--transition-slow) forwards;
}

.module-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 0.75rem;
}

.module-icon {
    font-size: 1.75rem;
    padding: 0.45rem;
    background: rgba(var(--accent-color), 0.06);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 1px solid rgba(var(--accent-color), 0.1);
}

.module-header-text h2 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--text-primary);
    letter-spacing: -0.01em;
}

.topic-counter {
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    color: rgb(var(--accent-color));
    background: rgba(var(--accent-color), 0.08);
    padding: 0.2rem 0.65rem;
    border-radius: 100px;
    display: inline-block;
    margin-top: 0.15rem;
    border: 1px solid rgba(var(--accent-color), 0.12);
}

.module-description {
    font-size: 0.925rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 2rem;
    max-width: 800px;
}

.topics-cards-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 1.5rem;
    width: 100%;
}

/* --- Concept Card (Light Premium Glassmorphism) --- */
.concept-card {
    background: var(--bg-card);
    border: 1px solid var(--border-card);
    border-radius: 18px;
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    gap: 1.25rem;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-main);
}

.concept-card::after {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 3px;
    width: 100%;
    background: linear-gradient(90deg, rgba(var(--accent-color), 0), rgba(var(--accent-color), 0.6), rgba(var(--accent-color), 0));
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.concept-card:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-card-hover);
    transform: translateY(-3px);
    box-shadow: var(--shadow-card-hover);
}

.concept-card:hover::after {
    opacity: 1;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    border-bottom: 1px solid var(--border-glow);
    padding-bottom: 0.75rem;
}

.card-header-left {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    min-width: 0;
}

.concept-id {
    font-size: 0.725rem;
    font-weight: 800;
    font-family: var(--font-display);
    padding: 0.15rem 0.5rem;
    border-radius: 6px;
    color: rgb(var(--accent-color));
    background: rgba(var(--accent-color), 0.08);
    border: 1px solid rgba(var(--accent-color), 0.15);
    flex-shrink: 0;
}

.card-header h3 {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.3;
    letter-spacing: -0.01em;
    word-break: break-word;
    font-family: var(--font-display);
}

.badge-key-concept {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    font-size: 0.625rem;
    font-weight: 750;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-secondary);
    background: var(--bg-surface-hover);
    border: 1px solid var(--border-hover);
    padding: 0.25rem 0.65rem;
    border-radius: 20px;
    font-family: var(--font-display);
    flex-shrink: 0;
}

.badge-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    display: inline-block;
    animation: pulse-dot 2s infinite ease-in-out;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 0.5; transform: scale(0.9); }
    50% { opacity: 1; transform: scale(1.1); }
}

.concept-card:not(.key-concept) {
    border-left: 3.5px solid rgba(var(--accent-color), 0.25);
}

.concept-card:not(.key-concept):hover {
    border-left-color: rgba(var(--accent-color), 0.85);
}

.concept-card.key-concept {
    background: linear-gradient(135deg, var(--bg-card) 0%, hsla(var(--accent-color), 0.035) 100%);
    border: 1px solid rgba(var(--accent-color), 0.18);
}

/* --- Concept Structured Sections --- */
.concept-structured-details {
    display: flex;
    flex-direction: column;
    gap: 0.95rem;
    flex-grow: 1;
}

.detail-item {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
    padding-left: 0.85rem;
    border-left: 2px solid rgba(var(--accent-color), 0.12);
    transition: border-color var(--transition-normal);
}

.concept-card:hover .detail-item {
    border-left-color: rgba(var(--accent-color), 0.4);
}

.detail-item.detail-resumo {
    background: rgba(var(--accent-color), 0.03);
    padding: 0.65rem 0.85rem;
    border-radius: 12px;
    border-left: 3px solid rgba(var(--accent-color), 0.35);
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.concept-card:hover .detail-item.detail-resumo {
    background: rgba(var(--accent-color), 0.06);
    border-left-color: rgba(var(--accent-color), 0.7);
}

.detail-label {
    font-size: 0.725rem;
    font-weight: 755;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: rgba(var(--accent-color), 0.9);
    font-family: var(--font-display);
}

.detail-text {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* --- Action Buttons --- */
.card-actions {
    display: flex;
    gap: 0.75rem;
    width: 100%;
    border-top: 1px solid var(--border-glow);
    padding-top: 0.85rem;
}

.btn-doc {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.45rem;
    padding: 0.6rem 0.75rem;
    border-radius: 10px;
    font-size: 0.8rem;
    font-weight: 700;
    text-decoration: none;
    color: var(--text-secondary);
    background: var(--bg-btn);
    border: 1px solid var(--border-btn);
    transition: all var(--transition-fast);
    font-family: var(--font-display);
}

.btn-doc:hover {
    color: rgb(var(--accent-color));
    background: var(--bg-btn-hover);
    border-color: rgba(var(--accent-color), 0.3);
    box-shadow: 0 4px 12px -3px rgba(var(--accent-color), 0.15);
}

.btn-flag {
    font-size: 1rem;
}

/* --- App Footer --- */
.app-footer {
    border-top: 1px solid var(--border-glow);
    padding: 2rem;
    text-align: center;
    background: var(--bg-footer);
    margin-top: auto;
    transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.app-footer p {
    font-size: 0.8rem;
    color: var(--text-muted);
}

/* --- Loader and states --- */
.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.25rem;
    padding: 8rem 2rem;
    width: 100%;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3.5px solid rgba(99, 102, 241, 0.08);
    border-top-color: #4f46e5;
    border-radius: 50%;
    animation: spin 1s infinite linear;
}

body.dark-theme .spinner {
    border-color: rgba(129, 140, 248, 0.1);
    border-top-color: #818cf8;
}

.error-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 4rem 2rem;
    border: 1px dashed rgba(239, 68, 68, 0.2);
    border-radius: 20px;
    max-width: 600px;
    margin: 4rem auto;
}

.error-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.error-state h2 {
    font-family: var(--font-display);
    font-size: 1.3rem;
    color: #ef4444;
    margin-bottom: 0.5rem;
}

.error-state p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.error-details {
    font-size: 0.775rem;
    font-family: monospace;
    background: rgba(239, 68, 68, 0.05);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    color: #ef4444;
}

.module-empty-state {
    padding: 4rem 2rem;
    text-align: center;
    border: 1px dashed var(--border-glow);
    border-radius: 16px;
    color: var(--text-muted);
    font-size: 0.9rem;
}

.global-empty-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 8rem 2rem;
    animation: fadeIn var(--transition-normal);
}

.empty-icon {
    font-size: 2.5rem;
    color: var(--text-muted);
    margin-bottom: 1rem;
}

.global-empty-state h3 {
    font-family: var(--font-display);
    font-size: 1.25rem;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.global-empty-state p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    max-width: 400px;
}

/* --- Keyframe Animations --- */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes tabReveal {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

@keyframes pulse {
    0%, 100% { transform: scale(1); filter: drop-shadow(0 0 10px rgba(99, 102, 241, 0.12)); }
    50% { transform: scale(1.02); filter: drop-shadow(0 0 15px rgba(99, 102, 241, 0.25)); }
}

@keyframes scalePulse {
    0% { transform: scale(0.98); }
    50% { transform: scale(1.015); }
    100% { transform: scale(1); }
}

.matched-search {
    animation: scalePulse 300ms ease-out;
}

/* --- Ambient Light Background Glows (Vibrant & Blur) --- */
.background-glow {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    pointer-events: none;
    z-index: -1;
    overflow: hidden;
}

.background-glow::before,
.background-glow::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(160px);
    opacity: 0.08;
    transition: opacity var(--transition-normal);
}

body.dark-theme .background-glow::before,
body.dark-theme .background-glow::after {
    opacity: 0.13;
}

.background-glow::before {
    top: -10%;
    right: -10%;
    width: 60vw;
    height: 60vw;
    background: radial-gradient(circle, #6366f1 0%, transparent 70%);
}

.background-glow::after {
    bottom: -15%;
    left: -10%;
    width: 50vw;
    height: 50vw;
    background: radial-gradient(circle, #06b6d4 0%, transparent 70%);
}

/* ==========================================================================
   --- MEDIA QUERIES & RESPONSIVENESS ---
   ========================================================================== */

/* Large screens / desktop transition */
@media (max-width: 1024px) {
    .app-sidebar {
        position: fixed;
        left: 0;
        top: 0;
        height: 100vh;
        transform: translateX(-100%);
        box-shadow: var(--shadow-main);
        width: 290px;
    }
    
    .app-sidebar.mobile-open {
        transform: translateX(0);
        box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.35);
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .app-header {
        padding: 1rem 2rem;
        justify-content: space-between;
    }
    
    .main-content {
        padding: 2rem;
    }
}

/* Tablets and lower */
@media (max-width: 768px) {
    .dashboard-banner {
        padding: 2rem;
        flex-direction: column;
        align-items: flex-start;
        gap: 1.5rem;
    }
    
    .banner-visual {
        display: none;
    }
    
    .topics-cards-container {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }
    
    .app-header {
        padding: 1rem 1.5rem;
    }
    
    .main-content {
        padding: 1.5rem 1rem;
    }
}

/* Ultra mobile devices (<320px) */
@media (max-width: 320px) {
    .dashboard-banner h2 {
        font-size: 1.45rem;
    }
    
    .concept-card {
        padding: 1.15rem 1rem;
    }
    
    .card-actions {
        flex-direction: column;
        gap: 0.5rem;
    }
}