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

:root {
    --primary: #10b981;
    --primary-dark: #059669;
    --secondary: #3b82f6;
    --accent: #f59e0b;
    --phase1: #10b981;
    --phase2: #3b82f6;
    --phase3: #f59e0b;
    --phase4: #8b5cf6;
    --bg-dark: #0f172a;
    --bg-card: #1e293b;
    --bg-hover: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border: #334155;
    --success: #22c55e;
    --error: #ef4444;
    --warning: #f59e0b;
}

body {
    font-family: 'Poppins', sans-serif;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navbar */
.navbar {
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 24px;
}

.logo {
    font-size: 24px;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: 32px;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

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

/* Hero */
.hero {
    padding: 80px 0 60px;
    text-align: center;
}

.hero-title {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 16px;
    background: linear-gradient(135deg, #fff, var(--primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-secondary);
    margin-bottom: 48px;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 40px;
    flex-wrap: wrap;
}

.stat-card {
    background: var(--bg-card);
    padding: 24px 40px;
    border-radius: 16px;
    border: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 48px;
    font-weight: 700;
    color: var(--primary);
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
}

/* Section */
.section-title {
    font-size: 32px;
    font-weight: 600;
    margin-bottom: 40px;
    text-align: center;
}

/* Learning Path */
.learning-path {
    padding: 60px 0;
}

.path-steps {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}

.path-step {
    background: var(--bg-card);
    padding: 24px 32px;
    border-radius: 16px;
    border: 2px solid var(--border);
    display: flex;
    align-items: center;
    gap: 16px;
    transition: all 0.3s;
}

.path-step.active {
    border-color: var(--primary);
    box-shadow: 0 0 20px rgba(16, 185, 129, 0.3);
}

.step-number {
    width: 48px;
    height: 48px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 20px;
}

.step-content h4 {
    font-size: 18px;
    margin-bottom: 4px;
}

.step-content p {
    font-size: 14px;
    color: var(--text-secondary);
}

.path-arrow {
    font-size: 32px;
    color: var(--text-secondary);
}

/* Projects */
.projects {
    padding: 60px 0 80px;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 24px;
}

.project-card {
    background: var(--bg-card);
    padding: 32px;
    border-radius: 16px;
    border: 1px solid var(--border);
    text-decoration: none;
    color: inherit;
    transition: all 0.3s;
    display: block;
}

.project-card:hover {
    transform: translateY(-4px);
    border-color: var(--primary);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

.project-card.phase-1 {
    border-left: 4px solid var(--phase1);
}

.project-card.phase-2 {
    border-left: 4px solid var(--phase2);
}

.project-card.phase-3 {
    border-left: 4px solid var(--phase3);
}

.project-card.phase-4 {
    border-left: 4px solid var(--phase4);
}

.project-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 20px;
    margin-bottom: 20px;
}

.project-card h4 {
    font-size: 20px;
    margin-bottom: 12px;
}

.project-card p {
    color: var(--text-secondary);
    font-size: 14px;
    margin-bottom: 16px;
}

.project-meta {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
}

.project-dataset {
    background: rgba(59, 130, 246, 0.2);
    color: var(--secondary);
    padding: 4px 12px;
    border-radius: 20px;
}

.project-difficulty {
    background: rgba(16, 185, 129, 0.2);
    color: var(--primary);
    padding: 4px 12px;
    border-radius: 20px;
}

/* Project Page */
.project-header {
    padding: 60px 0 40px;
}

.project-header h1 {
    font-size: 40px;
    margin-bottom: 16px;
}

.project-nav {
    display: flex;
    gap: 12px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.nav-btn {
    padding: 12px 24px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-secondary);
    cursor: pointer;
    font-family: 'Poppins', sans-serif;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s;
}

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

.back-btn {
    padding: 10px 20px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 8px;
    color: var(--text-secondary);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 24px;
    transition: all 0.3s;
}

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

.content-section {
    margin-bottom: 40px;
}

.content-section h2 {
    font-size: 28px;
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--border);
}

.content-section h3 {
    font-size: 20px;
    margin: 24px 0 12px;
    color: var(--primary);
}

.content-section p {
    margin-bottom: 16px;
    color: var(--text-secondary);
}

.code-block {
    background: #0f172a;
    padding: 20px;
    border-radius: 12px;
    margin: 16px 0;
    overflow-x: auto;
    font-family: 'Fira Code', monospace;
    font-size: 14px;
    border: 1px solid var(--border);
}

.code-block pre {
    margin: 0;
    color: #e2e8f0;
}

.keyword { color: #c084fc; }
.function { color: #60a5fa; }
.string { color: #34d399; }
.comment { color: #64748b; }
.number { color: #fbbf24; }

/* Code Editor */
.code-editor-section {
    background: var(--bg-card);
    border-radius: 16px;
    border: 1px solid var(--border);
    overflow: hidden;
    margin-bottom: 32px;
}

.editor-header {
    background: #0f172a;
    padding: 16px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border);
}

.editor-title {
    font-weight: 600;
}

.editor-actions {
    display: flex;
    gap: 12px;
}

.btn {
    padding: 10px 20px;
    border-radius: 8px;
    font-family: 'Poppins', sans-serif;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    border: none;
    transition: all 0.3s;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
}

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

.btn-secondary:hover {
    border-color: var(--primary);
}

.editor-body {
    display: flex;
    gap: 16px;
    padding: 16px;
}

.editor-container {
    flex: 1;
}

textarea.code-input {
    width: 100%;
    min-height: 300px;
    background: #0f172a;
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 14px;
    padding: 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    resize: vertical;
    line-height: 1.6;
}

textarea.code-input:focus {
    outline: none;
    border-color: var(--primary);
}

.output-container {
    flex: 1;
}

.output-box {
    width: 100%;
    min-height: 300px;
    background: #0f172a;
    color: #e2e8f0;
    font-family: 'Fira Code', monospace;
    font-size: 14px;
    padding: 16px;
    border: 1px solid var(--border);
    border-radius: 8px;
    white-space: pre-wrap;
    overflow-y: auto;
}

.output-success {
    color: var(--success);
}

.output-error {
    color: var(--error);
}

/* Exercises */
.exercise-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 20px;
}

.exercise-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}

.exercise-number {
    background: var(--primary);
    color: white;
    padding: 6px 14px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 14px;
}

.exercise-difficulty {
    font-size: 12px;
    padding: 4px 12px;
    border-radius: 12px;
}

.difficulty-easy {
    background: rgba(34, 197, 94, 0.2);
    color: var(--success);
}

.difficulty-medium {
    background: rgba(245, 158, 11, 0.2);
    color: var(--warning);
}

.difficulty-hard {
    background: rgba(239, 68, 68, 0.2);
    color: var(--error);
}

.exercise-question {
    font-size: 16px;
    margin-bottom: 16px;
    line-height: 1.7;
}

.exercise-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
}

.answer-section {
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
    display: none;
}

.answer-section.show {
    display: block;
}

/* Quiz */
.quiz-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    margin-bottom: 20px;
}

.quiz-question {
    font-size: 16px;
    margin-bottom: 16px;
}

.quiz-options {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.quiz-option {
    padding: 12px 16px;
    background: var(--bg-dark);
    border: 1px solid var(--border);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s;
}

.quiz-option:hover {
    border-color: var(--secondary);
}

.quiz-option.correct {
    border-color: var(--success);
    background: rgba(34, 197, 94, 0.1);
}

.quiz-option.incorrect {
    border-color: var(--error);
    background: rgba(239, 68, 68, 0.1);
}

.quiz-option.selected {
    border-color: var(--secondary);
}

.quiz-score {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 24px;
    text-align: center;
    margin-bottom: 24px;
}

.quiz-score h2 {
    font-size: 48px;
    color: var(--primary);
    margin-bottom: 8px;
}

/* Dataset Preview */
.dataset-preview {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 20px;
    margin: 20px 0;
}

.dataset-preview h4 {
    margin-bottom: 16px;
    font-size: 18px;
}

.data-table {
    overflow-x: auto;
}

.data-table table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
}

.data-table th,
.data-table td {
    padding: 10px 14px;
    text-align: left;
    border: 1px solid var(--border);
}

.data-table th {
    background: var(--bg-dark);
    font-weight: 600;
    color: var(--primary);
}

.data-table tr:nth-child(even) {
    background: rgba(15, 23, 42, 0.5);
}

/* Footer */
.footer {
    padding: 40px 0;
    border-top: 1px solid var(--border);
    text-align: center;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 32px;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .editor-body {
        flex-direction: column;
    }
    
    .path-steps {
        flex-direction: column;
    }
    
    .path-arrow {
        transform: rotate(90deg);
    }
}