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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary-color: #f59e0b;
    --accent-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --success-color: #22c55e;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --text-light: #9ca3af;
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --border-color: #e5e7eb;
    --border-light: #f3f4f6;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --border-radius-xl: 16px;
    --transition: all 0.3s ease;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
}

body {
    font-family: var(--font-family);
    color: var(--text-primary);
    background-color: var(--bg-primary);
    line-height: 1.6;
    font-size: 16px;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.header {
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: var(--transition);
}

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

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.navbar-brand {
    display: flex;
    align-items: center;
}

.logo-image {
    height: 80px;
    margin-right: 12px;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin: 0;
}

.logo-subtitle {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin: 0;
}

.navbar-menu {
    display: flex;
    align-items: center;
}

.navbar-nav {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: var(--transition);
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
    border-radius: 1px;
}

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    transition: var(--transition);
}

.main-content {
    margin-top: 80px;
}

.hero-section {
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23e5e7eb' fill-opacity='0.1'%3E%3Ccircle cx='30' cy='30' r='2'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E") repeat;
    opacity: 0.5;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.7;
}

.hero-stats {
    display: flex;
    gap: 2rem;
    margin-bottom: 2rem;
}

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

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: var(--bg-primary);
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

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

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-outline:hover {
    background: var(--bg-tertiary);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.btn-success:hover {
    background: #16a34a;
    transform: translateY(-2px);
}

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

.btn-warning:hover {
    background: #d97706;
    transform: translateY(-2px);
}

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

.btn-danger:hover {
    background: #dc2626;
    transform: translateY(-2px);
}

.btn-info {
    background: #06b6d4;
    color: white;
}

.btn-info:hover {
    background: #0891b2;
    transform: translateY(-2px);
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.math-animation {
    position: relative;
    width: 300px;
    height: 300px;
}

.formula-container {
    position: relative;
    width: 100%;
    height: 100%;
}

.formula {
    position: absolute;
    background: white;
    padding: 0.75rem 1rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-md);
    font-weight: 500;
    font-size: 1.125rem;
    color: var(--primary-color);
    animation: float 6s ease-in-out infinite;
}

.formula:nth-child(1) {
    top: 10%;
    left: 20%;
    animation-delay: 0s;
}

.formula:nth-child(2) {
    top: 30%;
    right: 10%;
    animation-delay: 1.2s;
}

.formula:nth-child(3) {
    bottom: 30%;
    left: 10%;
    animation-delay: 2.4s;
}

.formula:nth-child(4) {
    bottom: 10%;
    right: 20%;
    animation-delay: 3.6s;
}

.formula:nth-child(5) {
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    animation-delay: 4.8s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
    }
    25% {
        transform: translateY(-10px) rotate(1deg);
    }
    50% {
        transform: translateY(0px) rotate(0deg);
    }
    75% {
        transform: translateY(-5px) rotate(-1deg);
    }
}

.motivation-section {
    margin: 3rem 0;
    text-align: center;
}

.motivation-quote {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    max-width: 600px;
    margin: 0 auto;
}

.motivation-quote blockquote {
    font-size: 1.25rem;
    font-style: italic;
    color: var(--text-primary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.motivation-quote cite {
    color: var(--text-secondary);
    font-weight: 500;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

.feature-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.6;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-header p {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.categories-section,
.progress-section,
.about-section,
.contact-section {
    padding: 4rem 0;
}

.categories-filter {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.75rem 1.5rem;
    border: 2px solid var(--border-color);
    background: var(--bg-primary);
    color: var(--text-primary);
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

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

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.category-card {
    background: white;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    padding: 2rem;
    transition: var(--transition);
    cursor: pointer;
    border: 2px solid transparent;
}

.category-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.category-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    display: block;
}

.category-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.category-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.category-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-light);
}

.tasks-count {
    font-weight: 500;
    color: var(--text-secondary);
}

.difficulty-badge {
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
}

.difficulty-easy {
    background: #dcfce7;
    color: #16a34a;
}

.difficulty-medium {
    background: #fef3c7;
    color: #d97706;
}

.difficulty-hard {
    background: #fee2e2;
    color: #dc2626;
}

.category-detail,
.subcategory-detail,
.task-detail {
    animation: fadeInUp 0.5s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.back-btn {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 2rem;
    font-weight: 500;
}

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

.subcategories-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.subcategory-card {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    padding: 1.5rem;
    transition: var(--transition);
    cursor: pointer;
    border: 1px solid var(--border-color);
}

.subcategory-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.subcategory-progress {
    margin-top: 1rem;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
    transition: width 0.3s ease;
}

.progress-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.tasks-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.task-card {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-sm);
    padding: 1.5rem;
    transition: var(--transition);
    cursor: pointer;
    border: 1px solid var(--border-color);
    position: relative;
}

.task-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.task-card.solved {
    border-color: var(--success-color);
    background: linear-gradient(135deg, #f0fdf4, white);
}

.task-card.solved::after {
    content: '✓';
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--success-color);
    color: white;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
    font-weight: bold;
}

.task-number {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 500;
    display: inline-block;
    margin-bottom: 1rem;
}

.task-preview {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.task-content {
    max-width: 800px;
    margin: 0 auto;
}

.task-problem {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.problem-text {
    font-size: 1.125rem;
    line-height: 1.7;
    color: var(--text-primary);
}

.task-answer-section {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.answer-input-container {
    margin-bottom: 1.5rem;
}

.answer-input-container label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.answer-input-container input {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

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

.answer-actions {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

.answer-feedback {
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-top: 1rem;
}

.feedback-correct {
    background: #f0fdf4;
    border: 1px solid #16a34a;
    color: #16a34a;
}

.feedback-incorrect {
    background: #fef2f2;
    border: 1px solid #dc2626;
    color: #dc2626;
}

.feedback-partial {
    background: #fffbeb;
    border: 1px solid #d97706;
    color: #d97706;
}

.task-solution {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.solution-text {
    font-size: 1.125rem;
    line-height: 1.7;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.solution-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.task-navigation {
    display: flex;
    justify-content: space-between;
    gap: 1rem;
    margin-top: 2rem;
}

.progress-overview {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.progress-card {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    text-align: center;
}

.circular-progress {
    position: relative;
    width: 120px;
    height: 120px;
    margin: 1rem auto;
}

.progress-circle {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: conic-gradient(var(--primary-color) 0deg, var(--bg-tertiary) 0deg);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
}

.progress-circle::before {
    content: '';
    position: absolute;
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: white;
}

.progress-number {
    position: relative;
    z-index: 1;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.streak-counter {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 1rem 0;
}

.streak-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--secondary-color);
    line-height: 1;
}

.streak-label {
    color: var(--text-secondary);
    margin-top: 0.5rem;
}

.achievements {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.achievement {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    padding: 1rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
    min-width: 80px;
}

.achievement.locked {
    opacity: 0.5;
    filter: grayscale(100%);
}

.achievement:not(.locked) {
    background: var(--bg-secondary);
    transform: scale(1.05);
}

.achievement-icon {
    font-size: 2rem;
}

.achievement-name {
    font-size: 0.75rem;
    text-align: center;
    color: var(--text-secondary);
}

.detailed-progress {
    margin-bottom: 3rem;
}

.categories-progress {
    display: grid;
    gap: 1rem;
}

.category-progress-item {
    background: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.category-progress-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.category-progress-name {
    font-weight: 600;
    color: var(--text-primary);
}

.category-progress-stats {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.learning-analytics {
    margin-bottom: 3rem;
}

.analytics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.analytics-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.analytics-card h4 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.time-chart {
    display: flex;
    align-items: end;
    gap: 0.5rem;
    height: 100px;
}

.time-bar {
    flex: 1;
    background: var(--primary-color);
    border-radius: 4px 4px 0 0;
    position: relative;
    min-height: 10px;
    display: flex;
    align-items: end;
    justify-content: center;
    opacity: 0.7;
    transition: var(--transition);
}

.time-bar:hover {
    opacity: 1;
}

.time-bar span {
    position: absolute;
    bottom: -25px;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.time-bar::after {
    content: attr(data-day);
    position: absolute;
    bottom: -45px;
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.difficult-topics,
.recommendations {
    color: var(--text-secondary);
    line-height: 1.6;
}

.about-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.about-text h3 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.about-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.about-description {
    margin-bottom: 2rem;
}

.about-description p {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.qualifications,
.teaching-philosophy {
    margin-bottom: 2rem;
}

.qualifications h4,
.teaching-philosophy h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.qualifications ul {
    list-style: none;
    padding: 0;
}

.qualifications li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
    line-height: 1.6;
}

.qualifications li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
}

.teaching-philosophy blockquote {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    font-style: italic;
    color: var(--text-secondary);
    line-height: 1.7;
    margin: 0;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
}

.stat-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 1.5rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.stat-description {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.testimonials {
    margin-top: 3rem;
}

.testimonials h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 2rem;
    color: var(--text-primary);
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.testimonial-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    position: relative;
}

.testimonial-card::before {
    content: '"';
    position: absolute;
    top: -10px;
    left: 20px;
    font-size: 4rem;
    color: var(--primary-color);
    line-height: 1;
}

.testimonial-card p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1rem;
    padding-top: 1rem;
}

.testimonial-card cite {
    color: var(--primary-color);
    font-weight: 500;
    font-style: normal;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.contact-info h3,
.contact-form h3 {
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.contact-icon {
    font-size: 1.25rem;
    margin-top: 0.25rem;
}

.contact-item a {
    color: var(--primary-color);
    text-decoration: none;
}

.contact-item a:hover {
    text-decoration: underline;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    font-family: inherit;
}

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

.pricing-info {
    margin-top: 3rem;
}

.pricing-info h3 {
    text-align: center;
    margin-bottom: 2rem;
    font-size: 2rem;
    color: var(--text-primary);
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.pricing-card {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    border: 2px solid var(--border-color);
    text-align: center;
    transition: var(--transition);
}

.pricing-card.featured {
    border-color: var(--primary-color);
    transform: scale(1.05);
    background: linear-gradient(135deg, var(--bg-secondary), white);
}

.pricing-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.pricing-card.featured:hover {
    transform: scale(1.05) translateY(-5px);
}

.pricing-card h4 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.price {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.price span {
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: normal;
}

.pricing-card ul {
    list-style: none;
    padding: 0;
    text-align: left;
}

.pricing-card li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    position: relative;
    padding-left: 1.5rem;
}

.pricing-card li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--success-color);
    font-weight: bold;
}

.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
    color: white;
}

.footer-section p,
.footer-section li {
    color: #d1d5db;
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
    padding: 0;
}

.footer-section li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: #d1d5db;
    text-decoration: none;
    transition: var(--transition);
}

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

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-link {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    border-radius: var(--border-radius);
    text-decoration: none;
    color: white;
    transition: var(--transition);
}

.social-link:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
}

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 1rem;
    text-align: center;
    color: #9ca3af;
}

.footer-bottom p {
    margin-bottom: 0.5rem;
}

.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    backdrop-filter: blur(5px);
}

.loading-spinner {
    text-align: center;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .navbar-menu {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .categories-grid {
        grid-template-columns: 1fr;
    }
    
    .subcategories-container {
        grid-template-columns: 1fr;
    }
    
    .tasks-container {
        grid-template-columns: 1fr;
    }
    
    .progress-overview {
        grid-template-columns: 1fr;
    }
    
    .analytics-grid {
        grid-template-columns: 1fr;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .pricing-grid {
        grid-template-columns: 1fr;
    }
    
    .pricing-card.featured {
        transform: none;
    }
    
    .pricing-card.featured:hover {
        transform: translateY(-5px);
    }
    
    .testimonials-grid {
        grid-template-columns: 1fr;
    }
    
    .task-navigation {
        flex-direction: column;
    }
    
    .answer-actions {
        flex-direction: column;
    }
    
    .solution-actions {
        flex-direction: column;
    }
    
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 300px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }
    
    .section-header h2 {
        font-size: 2rem;
    }
    
    .about-text h3 {
        font-size: 1.5rem;
    }
    
    .categories-filter {
        flex-direction: column;
        align-items: center;
    }
    
    .filter-btn {
        width: 100%;
        max-width: 200px;
    }
    
    .time-chart {
        height: 80px;
    }
}

.hidden {
    display: none !important;
}

.fade-in {
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.slide-up {
    animation: slideUp 0.5s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.pulse {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
    100% {
        transform: scale(1);
    }
}

.shake {
    animation: shake 0.5s ease-in-out;
}

@keyframes shake {
    0%, 100% {
        transform: translateX(0);
    }
    25% {
        transform: translateX(-5px);
    }
    75% {
        transform: translateX(5px);
    }
}

.bounce {
    animation: bounce 0.6s ease;
}

@keyframes bounce {
    0%, 20%, 53%, 80%, 100% {
        transform: translate3d(0, 0, 0);
    }
    40%, 43% {
        transform: translate3d(0, -10px, 0);
    }
    70% {
        transform: translate3d(0, -5px, 0);
    }
    90% {
        transform: translate3d(0, -2px, 0);
    }
}

.glow {
    box-shadow: 0 0 20px rgba(37, 99, 235, 0.3);
}

.text-gradient {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.card-hover {
    transition: var(--transition);
}

.card-hover:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
}

.glass-effect {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.gradient-bg {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
}

.text-shadow {
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
}

.border-gradient {
    border: 2px solid transparent;
    background: linear-gradient(white, white) padding-box,
                linear-gradient(135deg, var(--primary-color), var(--primary-dark)) border-box;
}

.scrollbar-custom {
    scrollbar-width: thin;
    scrollbar-color: var(--primary-color) var(--bg-tertiary);
}

.scrollbar-custom::-webkit-scrollbar {
    width: 8px;
}

.scrollbar-custom::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

.scrollbar-custom::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 4px;
}

.scrollbar-custom::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

.tooltip {
    position: relative;
    cursor: help;
}

.tooltip::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: white;
    padding: 0.5rem;
    border-radius: var(--border-radius);
    font-size: 0.875rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: var(--transition);
    z-index: 1000;
}

.tooltip:hover::after {
    opacity: 1;
    bottom: calc(100% + 5px);
}

.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

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

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

.badge-warning {
    background: var(--warning-color);
    color: white;
}

.badge-danger {
    background: var(--danger-color);
    color: white;
}

.badge-info {
    background: #06b6d4;
    color: white;
}

.badge-light {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.alert {
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    border: 1px solid transparent;
}

.alert-success {
    background: #f0fdf4;
    border-color: #16a34a;
    color: #16a34a;
}

.alert-warning {
    background: #fffbeb;
    border-color: #d97706;
    color: #d97706;
}

.alert-danger {
    background: #fef2f2;
    border-color: #dc2626;
    color: #dc2626;
}

.alert-info {
    background: #f0f9ff;
    border-color: #0ea5e9;
    color: #0ea5e9;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.modal.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: white;
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    max-width: 500px;
    width: 90%;
    transform: scale(0.8);
    transition: var(--transition);
}

.modal.active .modal-content {
    transform: scale(1);
}

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

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    transition: var(--transition);
}

.modal-close:hover {
    color: var(--text-primary);
}

.progress-ring {
    width: 120px;
    height: 120px;
    transform: rotate(-90deg);
}

.progress-ring-circle {
    fill: none;
    stroke: var(--bg-tertiary);
    stroke-width: 8;
}

.progress-ring-progress {
    fill: none;
    stroke: var(--primary-color);
    stroke-width: 8;
    stroke-linecap: round;
    transition: stroke-dasharray 0.3s ease;
}

.floating-action {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    background: var(--primary-color);
    color: white;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
    z-index: 1000;
}

.floating-action:hover {
    background: var(--primary-dark);
    transform: scale(1.1);
}

.skeleton {
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: loading 1.5s infinite;
}

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

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.font-light { font-weight: 300; }
.font-normal { font-weight: 400; }
.font-medium { font-weight: 500; }
.font-semibold { font-weight: 600; }
.font-bold { font-weight: 700; }

.text-xs { font-size: 0.75rem; }
.text-sm { font-size: 0.875rem; }
.text-base { font-size: 1rem; }
.text-lg { font-size: 1.125rem; }
.text-xl { font-size: 1.25rem; }
.text-2xl { font-size: 1.5rem; }
.text-3xl { font-size: 1.875rem; }
.text-4xl { font-size: 2.25rem; }

.m-0 { margin: 0; }
.m-1 { margin: 0.25rem; }
.m-2 { margin: 0.5rem; }
.m-3 { margin: 0.75rem; }
.m-4 { margin: 1rem; }
.m-5 { margin: 1.25rem; }

.p-0 { padding: 0; }
.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 0.75rem; }
.p-4 { padding: 1rem; }
.p-5 { padding: 1.25rem; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 0.75rem; }
.mt-4 { margin-top: 1rem; }
.mt-5 { margin-top: 1.25rem; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 0.75rem; }
.mb-4 { margin-bottom: 1rem; }
.mb-5 { margin-bottom: 1.25rem; }

.flex { display: flex; }
.inline-flex { display: inline-flex; }
.grid { display: grid; }
.block { display: block; }
.inline-block { display: inline-block; }
.hidden { display: none; }

.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.justify-around { justify-content: space-around; }
.justify-evenly { justify-content: space-evenly; }

.items-center { align-items: center; }
.items-start { align-items: flex-start; }
.items-end { align-items: flex-end; }

.gap-1 { gap: 0.25rem; }
.gap-2 { gap: 0.5rem; }
.gap-3 { gap: 0.75rem; }
.gap-4 { gap: 1rem; }
.gap-5 { gap: 1.25rem; }

.w-full { width: 100%; }
.h-full { height: 100%; }

.rounded { border-radius: var(--border-radius); }
.rounded-lg { border-radius: var(--border-radius-lg); }
.rounded-xl { border-radius: var(--border-radius-xl); }
.rounded-full { border-radius: 50%; }

.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-xl { box-shadow: var(--shadow-xl); }

.bg-primary { background-color: var(--bg-primary); }
.bg-secondary { background-color: var(--bg-secondary); }
.bg-tertiary { background-color: var(--bg-tertiary); }

.text-primary { color: var(--text-primary); }
.text-secondary { color: var(--text-secondary); }
.text-light { color: var(--text-light); }

.border { border: 1px solid var(--border-color); }
.border-2 { border: 2px solid var(--border-color); }
.border-primary { border-color: var(--primary-color); }
.border-secondary { border-color: var(--secondary-color); }

.opacity-0 { opacity: 0; }
.opacity-50 { opacity: 0.5; }
.opacity-75 { opacity: 0.75; }
.opacity-100 { opacity: 1; }

.transform { transform: translateZ(0); }
.scale-105 { transform: scale(1.05); }
.scale-110 { transform: scale(1.1); }

.transition { transition: var(--transition); }

.cursor-pointer { cursor: pointer; }
.cursor-default { cursor: default; }
.cursor-not-allowed { cursor: not-allowed; }

.select-none { user-select: none; }
.select-all { user-select: all; }

.pointer-events-none { pointer-events: none; }
.pointer-events-auto { pointer-events: auto; }

.overflow-hidden { overflow: hidden; }
.overflow-auto { overflow: auto; }
.overflow-scroll { overflow: scroll; }

.relative { position: relative; }
.absolute { position: absolute; }
.fixed { position: fixed; }
.sticky { position: sticky; }

.top-0 { top: 0; }
.right-0 { right: 0; }
.bottom-0 { bottom: 0; }
.left-0 { left: 0; }

.z-10 { z-index: 10; }
.z-20 { z-index: 20; }
.z-30 { z-index: 30; }
.z-40 { z-index: 40; }
.z-50 { z-index: 50; }