:root {
    --primary-color: #00F5A0;
    --secondary-color: #00D186;
    --accent-color: #00B26A;
    --success-color: #00F5A0;
    --warning-color: #FFCE00;
    --danger-color: #FF4757;
    --text-primary: #ffffff;
    --text-secondary: #C4C4C4;
    --text-light: #9ca3af;
    --background-primary: #0D1117;
    --background-secondary: #1A1E23;
    --background-accent: #0D1117;
    --border-color: #2D3748;
    --border-color-hover: #4A5568;
    
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
    
    --border-radius-sm: 4px;
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --border-radius-xl: 16px;
    --border-radius-full: 9999px;
    
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-family-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Consolas', 'Courier New', monospace;
    --font-weight-normal: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --line-height-base: 1.6;
    --line-height-relaxed: 1.7;
    --letter-spacing-tight: -0.025em;
    
    --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: 2.5rem;
    
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-base: 0.75rem;
    --spacing-lg: 1rem;
    --spacing-xl: 1.5rem;
    --spacing-2xl: 2rem;
    --spacing-3xl: 3rem;
    --spacing-4xl: 4rem;
    --spacing-5xl: 5rem;
    
    --container-max-width: 1400px;
    --container-padding: 1rem;
    --container-padding-sm: 0.75rem;
    --grid-gap: 1.5rem;
    --grid-gap-sm: 1rem;
    
    --transition-fast: 0.15s ease-out;
    --transition-normal: 0.3s ease-out;
    --transition-slow: 0.5s ease-out;
    
    /* Z-index scale */
    --z-index-dropdown: 100;
    --z-index-modal: 1000;
    
    --breakpoint-tablet: 768px;
    --breakpoint-mobile: 480px;
}

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


body {
    font-family: var(--font-family);
    line-height: var(--line-height-base);
    color: var(--text-primary);
    background-color: var(--background-primary);
}

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

.container-fluid {
    max-width: 100%;
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.landing-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: var(--z-index-modal);
    background: rgba(13, 17, 23, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.navbar {
    padding: 0 20px;
    height: 80px;
    display: flex;
    align-items: center;
    width: 100%;
    justify-content: space-between;
}

.navbar__brand {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-primary);
    margin-left: 0;
}

.navbar__logo {
    height: 45px;
    width: auto;
    object-fit: contain;
    display: block;
    vertical-align: middle;
}

.navbar__actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
    height: 80px;
    margin-right: 0;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-sm);
}

.mobile-menu-toggle span {
    width: 20px;
    height: 2px;
    background: var(--text-primary);
    transition: all var(--transition-fast);
}

.challenges-hero {
    background: var(--background-secondary);
    padding: calc(80px + var(--spacing-3xl)) 0 var(--spacing-3xl);
    border-bottom: 1px solid var(--border-color);
}

.challenges-hero__content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.challenges-hero__title {
    font-size: var(--font-size-4xl);
    font-weight: var(--font-weight-bold);
    margin: 0 0 var(--spacing-lg);
    color: var(--text-primary);
    letter-spacing: var(--letter-spacing-tight);
}

.challenges-hero__subtitle {
    font-size: var(--font-size-lg);
    color: var(--text-secondary);
    margin: 0;
    font-weight: var(--font-weight-normal);
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: var(--font-weight-semibold);
    font-size: var(--font-size-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
    position: relative;
    display: inline-flex;
    align-items: center;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: all var(--transition-fast);
    transform: translateX(-50%);
}

.nav-link:hover::after {
    width: 80%;
}

.btn-back svg {
    margin-right: 8px;
}

/* Screen reader only class for accessibility */
.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;
}

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

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

.header__actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.user-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
}

.user-avatar {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    color: var(--background-primary);
}

.main {
    min-height: calc(100vh - 200px);
}

.challenge-hub {
    padding: calc(var(--spacing-5xl) + 60px) var(--spacing-5xl) var(--spacing-5xl) var(--spacing-5xl);
    background: var(--background-primary);
    position: relative;
    overflow: hidden;
}

.challenge-hub::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 50%;
    height: 100%;
    background: radial-gradient(ellipse at center, rgba(0, 245, 160, 0.03) 0%, transparent 70%);
    pointer-events: none;
}

.hub-header {
    text-align: center;
    margin-bottom: var(--spacing-5xl);
    position: relative;
    z-index: 1;
}

.hub-title {
    font-size: var(--font-size-5xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin-bottom: var(--spacing-3xl);
    background: linear-gradient(135deg, var(--text-primary), rgba(255, 255, 255, 0.8));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: 0 2px 20px rgba(0, 245, 160, 0.2);
}

.progress-overview {
    max-width: 700px;
    margin: 0 auto;
    background: linear-gradient(145deg, rgba(13, 17, 23, 0.9), rgba(26, 30, 35, 0.7));
    backdrop-filter: blur(10px);
    border: 1px solid rgba(0, 245, 160, 0.2);
    border-radius: var(--border-radius-xl);
    padding: var(--spacing-3xl);
    box-shadow: 
        0 8px 32px rgba(0, 0, 0, 0.4),
        inset 0 1px 0 rgba(255, 255, 255, 0.1);
}

.progress-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.stat {
    text-align: center;
    padding: var(--spacing-xl);
    background: rgba(0, 245, 160, 0.05);
    border-radius: var(--border-radius-lg);
    border: 1px solid rgba(0, 245, 160, 0.1);
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.stat::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(0, 245, 160, 0.1), transparent);
    transition: left 0.6s;
}

.stat:hover::before {
    left: 100%;
}

.stat:hover {
    transform: translateY(-2px);
    border-color: rgba(0, 245, 160, 0.3);
    box-shadow: 0 4px 16px rgba(0, 245, 160, 0.2);
}

.stat-number {
    display: block;
    font-size: var(--font-size-3xl);
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    position: relative;
    z-index: 1;
}

.stat-label {
    font-size: var(--font-size-base);
    color: var(--text-secondary);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    position: relative;
    z-index: 1;
}

.progress-bar {
    background: var(--background-primary);
    border: 1px solid rgba(0, 245, 160, 0.2);
    border-radius: var(--border-radius-full);
    height: 12px;
    overflow: hidden;
    position: relative;
    box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
}

.progress-fill {
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color), var(--primary-color));
    background-size: 200% 100%;
    height: 100%;
    width: 0%;
    transition: width var(--transition-slow);
    border-radius: var(--border-radius-full);
    position: relative;
    animation: shimmer 2s ease-in-out infinite;
}

@keyframes shimmer {
    0% { background-position: -200% 0; }
    100% { background-position: 200% 0; }
}

.challenge-filters {
    display: flex;
    align-items: end;
    justify-content: center;
    gap: var(--spacing-2xl);
    margin: var(--spacing-4xl) 0;
    flex-wrap: wrap;
    position: relative;
    z-index: 1;
}

.filter-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    position: relative;
}

.filter-group label {
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-bold);
    color: var(--primary-color);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-xs);
}

.filter-select {
    padding: var(--spacing-lg) var(--spacing-xl);
    border: 2px solid rgba(0, 245, 160, 0.2);
    border-radius: var(--border-radius-lg);
    background: linear-gradient(145deg, rgba(13, 17, 23, 0.95), rgba(26, 30, 35, 0.8));
    backdrop-filter: blur(10px);
    color: var(--text-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all var(--transition-fast);
    outline: none;
    min-width: 160px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.2);
    position: relative;
}

.filter-select::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(45deg, rgba(0, 245, 160, 0.1), transparent);
    opacity: 0;
    transition: opacity var(--transition-fast);
    border-radius: var(--border-radius-lg);
}

.filter-select:hover::before {
    opacity: 1;
}

.filter-select:focus,
.filter-select:hover {
    border-color: rgba(0, 245, 160, 0.5);
    box-shadow: 0 0 0 2px rgba(0, 245, 160, 0.2), 0 8px 24px rgba(0, 0, 0, 0.3);
    transform: translateY(-2px);
}

.challenges-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(420px, 1fr));
    gap: var(--spacing-2xl);
    align-items: start;
}

.challenge-card {
    background: var(--background-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-2xl);
    transition: all var(--transition-normal);
    cursor: pointer;
    position: relative;
    overflow: visible;
    display: flex;
    flex-direction: column;
    min-height: 100%;
    height: auto;
}

.challenge-card:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.challenge-card.completed {
    border-color: var(--success-color);
    background: linear-gradient(135deg, var(--background-secondary), rgba(0, 245, 160, 0.05));
}

.challenge-card.completed::after {
    content: '✓';
    position: absolute;
    top: var(--spacing-lg);
    right: var(--spacing-lg);
    width: 24px;
    height: 24px;
    background: var(--success-color);
    color: var(--background-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: var(--font-weight-bold);
    font-size: var(--font-size-sm);
}

.challenge-header {
    margin-bottom: var(--spacing-lg);
}

.challenge-title-section {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    flex: 1;
    min-width: 0;
}

.technology-icon {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--background-secondary);
    border-radius: var(--border-radius);
    border: 1px solid var(--border-color);
}

.tech-icon-img {
    width: 24px;
    height: 24px;
    transition: all var(--transition-fast);
    filter: grayscale(1) opacity(0.7);
}

.challenge-card:hover .technology-icon {
    border-color: var(--primary-color);
    background: rgba(0, 245, 160, 0.1);
}

.challenge-card:hover .tech-icon-img {
    filter: grayscale(0) opacity(1);
    transform: scale(1.05);
}

.challenge-card.completed .technology-icon {
    background: rgba(0, 245, 160, 0.2);
    border-color: var(--success-color);
}

.challenge-card.completed .tech-icon-img {
    filter: grayscale(0) opacity(1);
}

.challenge-title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin: 0;
    flex: 1;
    word-wrap: break-word;
    overflow-wrap: break-word;
    line-height: 1.3;
}

.challenge-badges {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
    justify-content: flex-start;
    margin-top: var(--spacing-lg);
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.difficulty-badge {
    padding: calc(var(--spacing-xs) * 0.5) var(--spacing-sm);
    border-radius: var(--border-radius-full);
    font-size: calc(var(--font-size-xs) * 0.9);
    font-weight: var(--font-weight-semibold);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    text-align: center;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.difficulty-badge.beginner {
    background-color: rgba(0, 245, 160, 0.2);
    color: var(--success-color);
}

.difficulty-badge.intermediate {
    background-color: rgba(255, 206, 0, 0.2);
    color: var(--warning-color);
}

.difficulty-badge.advanced {
    background-color: rgba(255, 71, 87, 0.2);
    color: var(--danger-color);
}

.tech-badge {
    padding: calc(var(--spacing-xs) * 0.5) var(--spacing-sm);
    border-radius: var(--border-radius);
    font-size: calc(var(--font-size-xs) * 0.9);
    font-weight: var(--font-weight-semibold);
    background-color: rgba(0, 245, 160, 0.1);
    color: var(--primary-color);
    border: 1px solid rgba(0, 245, 160, 0.2);
    white-space: nowrap;
    flex-shrink: 0;
    text-align: center;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.challenge-description {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    line-height: var(--line-height-relaxed);
    flex: 1;
}

.challenge-objectives {
    margin-top: auto;
}

.challenge-objectives h4 {
    color: var(--primary-color);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-base);
}

.objectives-list {
    list-style: none;
    padding: 0;
}

.objectives-list li {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-xs);
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.objectives-list li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: var(--font-weight-bold);
}

.challenge-description h4 {
    color: var(--primary-color);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-lg);
    margin-top: var(--spacing-2xl);
}

.challenge-description h4:first-child {
    margin-top: 0;
}

.tips-list {
    list-style: none;
    padding: 0;
    background: rgba(0, 245, 160, 0.05);
    border-left: 4px solid var(--primary-color);
    border-radius: var(--border-radius);
    padding: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.tips-list li {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    padding-left: var(--spacing-lg);
    position: relative;
    margin-bottom: var(--spacing-sm);
    line-height: var(--line-height-relaxed);
}

.tips-list li:last-child {
    margin-bottom: 0;
}

.tips-list li::before {
    content: '💡';
    position: absolute;
    left: 0;
    font-size: var(--font-size-xs);
}

.challenge-workspace {
    padding: calc(80px + var(--spacing-2xl)) var(--spacing-2xl) var(--spacing-2xl);
    min-height: 100vh;
    height: auto;
    overflow: visible;
}

.workspace-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
    gap: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: var(--spacing-lg);
}

.challenge-workspace .workspace-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
    gap: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: var(--spacing-lg);
}

.workspace-actions {
    display: flex;
    gap: var(--spacing-lg);
    flex-shrink: 0;
}

.challenge-workspace .workspace-actions {
    display: flex;
    gap: var(--spacing-lg);
    flex-shrink: 0;
}

.challenge-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.current-challenge-title {
    font-size: var(--font-size-2xl);
    font-weight: var(--font-weight-bold);
    color: var(--text-primary);
    margin: 0;
}

.challenge-meta {
    display: flex;
    gap: var(--spacing-sm);
}

.workspace-actions {
    display: flex;
    gap: var(--spacing-lg);
}

.workspace-content {
    display: grid;
    grid-template-columns: 0.2fr 0.8fr;
    gap: var(--spacing-2xl);
    min-height: 100vh;
    height: auto;
}

.challenge-workspace .challenge-description {
    background: var(--background-secondary);
    border: none;
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-xl);
    overflow-y: auto;
    height: 90vh;
    max-height: 90vh;
    max-width: 100%;
}

/* Hide scrollbar for challenge description */
.challenge-workspace .challenge-description::-webkit-scrollbar {
    display: none;
}

.challenge-workspace .challenge-description {
    -ms-overflow-style: none;
    scrollbar-width: none;
}

.challenge-description h4 {
    color: var(--primary-color);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-lg);
}

.code-workspace {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    grid-column: 2;
    align-items: start;
    height: 90vh;
    min-height: 90vh;
}

.editor-section,
.preview-section {
    background: var(--background-secondary);
    border: none;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    display: flex;
    flex-direction: column;
    height: 90vh;
}

.editor-header,
.preview-header {
    background: var(--background-primary);
    border-bottom: none;
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.editor-title-section {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
}

.editor-controls {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

.theme-selector {
    background: var(--background-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: border-color var(--transition-fast);
}

.theme-selector:hover {
    border-color: var(--border-color-hover);
}

.theme-selector:focus {
    outline: none;
    border-color: var(--primary-color);
}

.preview-header {
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
}

.editor-header h4,
.preview-header h4 {
    color: var(--text-primary);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin: 0;
}

.editor-tabs {
    display: flex;
    gap: var(--spacing-sm);
}

.tab-btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: var(--background-secondary);
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.tab-btn.active,
.tab-btn:hover {
    background: var(--primary-color);
    color: var(--background-primary);
    border-color: var(--primary-color);
}

.editor-container {
    flex: 1;
    position: relative;
    height: calc(90vh - 120px);
    min-height: calc(90vh - 120px);
    max-height: calc(90vh - 120px);
    overflow: hidden;
}

.editor-container .CodeMirror {
    height: calc(90vh - 120px) !important;
    font-family: var(--font-family-mono);
    font-size: var(--font-size-sm);
}

.editor-container .CodeMirror-scroll {
    height: calc(90vh - 120px) !important;
    overflow-y: auto !important;
    overflow-x: auto !important;
}

.editor-container .CodeMirror-scrollbar-filler {
    background-color: var(--background-secondary);
}

.editor-container .CodeMirror-vscrollbar,
.editor-container .CodeMirror-hscrollbar {
    background-color: var(--background-secondary);
}

.editor-container .CodeMirror-scrollbar-inner {
    background-color: var(--border-color);
    border-radius: var(--border-radius);
}

.editor-container .CodeMirror-scrollbar-inner:hover {
    background-color: var(--border-color-hover);
}

/* Hide scrollbar for CodeMirror editor */
.editor-container .CodeMirror-vscrollbar {
    display: none !important;
}

.editor-container .CodeMirror-hscrollbar {
    display: none !important;
}

.editor-container .CodeMirror-scrollbar-filler {
    display: none !important;
}

.preview-container {
    flex: 1;
    background: var(--background-primary);
    height: calc(90vh - 120px);
    min-height: calc(90vh - 120px);
    max-height: calc(90vh - 120px);
    overflow-y: auto;
}

.preview-container iframe {
    width: 100%;
    height: calc(90vh - 120px);
    border: none;
    background: white;
}

/* CodeMirror autocomplete styles */
.CodeMirror-hints {
    background: var(--background-secondary) !important;
    border: 1px solid var(--border-color) !important;
    border-radius: var(--border-radius) !important;
    box-shadow: var(--shadow-lg) !important;
    color: var(--text-primary) !important;
    font-family: var(--font-family-mono) !important;
    font-size: var(--font-size-sm) !important;
    z-index: 1000 !important;
}

.CodeMirror-hint {
    color: var(--text-primary) !important;
    padding: var(--spacing-xs) var(--spacing-sm) !important;
    border-radius: var(--border-radius-sm) !important;
    margin: 2px !important;
}

.CodeMirror-hint-active {
    background: var(--primary-color) !important;
    color: var(--background-primary) !important;
}

/* Hide scrollbar for preview container */
.preview-container::-webkit-scrollbar {
    display: none;
}

.preview-container {
    -ms-overflow-style: none;
    scrollbar-width: none;
}

/* Format message styles */
.format-message {
    position: absolute;
    top: 100%;
    right: var(--spacing-lg);
    background: var(--background-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-sm);
    z-index: 1000;
    animation: slideDown 0.3s ease-out;
}

.format-message--success {
    border-color: var(--success-color);
    color: var(--success-color);
    background: rgba(0, 245, 160, 0.1);
}

.format-message--error {
    border-color: var(--danger-color);
    color: var(--danger-color);
    background: rgba(255, 71, 87, 0.1);
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Editor controls responsive */
@media (max-width: 768px) {
    .editor-title-section {
        flex-direction: column;
        align-items: stretch;
        gap: var(--spacing-sm);
    }
    
    .editor-controls {
        justify-content: flex-end;
    }
    
    .theme-selector {
        font-size: var(--font-size-xs);
        padding: var(--spacing-xs);
    }
}

.test-results {
    grid-column: 1 / -1;
    margin-top: var(--spacing-4xl);
    position: relative;
    z-index: 10;
    display: none;
}

.test-results.has-content {
    display: block;
    min-height: 300px;
}

.results-panel {
    background: var(--background-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
}

.results-header {
    background: var(--background-primary);
    border-bottom: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.results-header:hover {
    background: rgba(255, 255, 255, 0.05);
}

.results-toggle-icon {
    transition: transform 0.3s ease;
    display: inline-block;
    font-size: 1.2em;
}

.results-toggle-icon.collapsed {
    transform: rotate(-90deg);
}

.results-content {
    max-height: 400px;
    overflow-y: auto;
    transition: all 0.3s ease;
    opacity: 1;
    padding: var(--spacing-lg);
}

.results-content.collapsed {
    max-height: 0;
    opacity: 0;
    padding: 0 !important;
    margin: 0;
    overflow: hidden;
}

.results-header h4 {
    color: var(--text-primary);
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-semibold);
    margin: 0;
}

.results-content {
    padding: var(--spacing-lg);
}

.test-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
}

.test-summary.success {
    background: rgba(0, 245, 160, 0.1);
    border: 1px solid rgba(0, 245, 160, 0.2);
}

.test-summary.failure {
    background: rgba(255, 71, 87, 0.1);
    border: 1px solid rgba(255, 71, 87, 0.2);
}

.summary-text {
    font-weight: var(--font-weight-semibold);
}

.summary-text.success {
    color: var(--success-color);
}

.summary-text.failure {
    color: var(--danger-color);
}

.test-score {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
}

.test-list {
    list-style: none;
    padding: 0;
}

.test-item {
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    margin-bottom: var(--spacing-lg);
    border-left: 4px solid;
}

.test-item.passed {
    background: rgba(0, 245, 160, 0.05);
    border-left-color: var(--success-color);
}

.test-item.failed {
    background: rgba(255, 71, 87, 0.05);
    border-left-color: var(--danger-color);
}

.test-name {
    font-weight: var(--font-weight-semibold);
    margin-bottom: var(--spacing-sm);
}

.test-name.passed {
    color: var(--success-color);
}

.test-name.failed {
    color: var(--danger-color);
}

.test-message {
    color: var(--text-secondary);
    font-size: var(--font-size-sm);
    line-height: var(--line-height-relaxed);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-base) var(--spacing-xl);
    border: none;
    border-radius: var(--border-radius);
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-semibold);
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-family: inherit;
}

.btn--primary {
    background-color: var(--primary-color);
    color: var(--background-primary);
    font-weight: var(--font-weight-bold);
}

.btn--primary:hover {
    background-color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn--secondary {
    background-color: var(--background-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn--secondary:hover {
    background-color: var(--background-primary);
    border-color: var(--primary-color);
    transform: translateY(-1px);
}

.btn--success {
    background-color: var(--success-color);
    color: var(--background-primary);
    font-weight: var(--font-weight-bold);
}

.btn--success:hover {
    background-color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn--small {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-xs);
}

.hidden {
    display: none !important;
}

.footer {
    background-color: var(--background-primary);
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-2xl) 0;
    text-align: center;
    margin-top: auto;
}

@media (max-width: 1200px) {
    .challenges-list {
        grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    }
    
    .workspace-content {
        grid-template-columns: 1fr;
        grid-template-rows: auto 1fr auto;
    }
    
    .code-workspace {
        grid-column: 1;
        grid-template-columns: 1fr;
        grid-template-rows: 1fr 300px;
    }
    
    .challenge-workspace .challenge-description {
        min-height: 300px;
        margin-bottom: var(--spacing-xl);
    }
}

@media (max-width: 850px) {
    .challenge-badges {
        flex: none;
        justify-content: flex-start;
        margin-top: var(--spacing-sm);
        width: 100%;
    }
}


@media (max-width: var(--breakpoint-tablet)) {
    .progress-stats {
        gap: var(--spacing-xl);
    }
    
    .challenge-filters {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .challenges-list {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
    
    .challenge-card {
        padding: var(--spacing-xl);
        min-height: auto;
    }
    
    .challenge-header {
        gap: var(--spacing-base);
    }
    
    
    .challenge-badges {
        flex: 1 1 100%;
        justify-content: flex-start;
        gap: var(--spacing-xs);
    }
    
    .technology-icon {
        width: 36px;
        height: 36px;
    }
    
    .tech-icon-img {
        width: 20px;
        height: 20px;
    }
    
    .workspace-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .challenge-info {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .workspace-actions {
        width: 100%;
        justify-content: center;
        margin-top: var(--spacing-lg);
    }
    
    .workspace-content {
        height: auto;
        min-height: auto;
    }
}

@media (max-width: var(--breakpoint-mobile)) {
    .container,
    .container-fluid {
        padding: 0 var(--container-padding-sm);
    }
    
    .header {
        padding: var(--spacing-xl) 0;
    }
    
    .header__title {
        font-size: var(--font-size-3xl);
    }
    
    .challenge-hub {
        padding: var(--spacing-2xl) 0;
    }
    
    .hub-title {
        font-size: var(--font-size-3xl);
    }
    
    .progress-stats {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .challenge-card {
        padding: var(--spacing-xl);
    }
    
    .workspace-actions {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
}

/* Button loading animation */
.btn--loading {
    position: relative;
    pointer-events: none;
}

.btn-loading-spinner {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: white;
    animation: spin 1s linear infinite;
    margin-right: var(--spacing-sm);
}

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