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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: 20px;
    line-height: 1.6;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    background: white;
    border-radius: 25px;
    padding: 40px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

h1 {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 2.5em;
    margin-bottom: 10px;
    text-align: center;
    font-weight: 700;
}

.subtitle {
    text-align: center;
    color: #718096;
    font-size: 1.2em;
    margin-bottom: 30px;
}

.video-container {
    position: relative;
    width: 100%;
    max-width: 800px;
    margin: 30px auto;
    padding-bottom: 56.25%;
    height: 0;
    overflow: hidden;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.section {
    margin-bottom: 35px;
    padding: 25px;
    background: #f8f9fa;
    border-radius: 15px;
    border-left: 5px solid #667eea;
}

h2 {
    color: #2d3748;
    font-size: 1.8em;
    margin-bottom: 15px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.icon {
    font-size: 1.2em;
}

p {
    color: #4a5568;
    margin-bottom: 15px;
    font-size: 1.05em;
}

.info-box {
    background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb 100%);
    padding: 20px;
    border-radius: 12px;
    margin: 20px 0;
    border-left: 4px solid #2196f3;
}

.info-box strong {
    color: #1565c0;
    display: block;
    margin-bottom: 8px;
    font-size: 1.1em;
}

.warning-box {
    background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 100%);
    padding: 20px;
    border-radius: 12px;
    margin: 20px 0;
    border-left: 4px solid #ff9800;
}

.warning-box strong {
    color: #e65100;
    display: block;
    margin-bottom: 8px;
    font-size: 1.1em;
}

.success-box {
    background: linear-gradient(135deg, #e8f5e9 0%, #c8e6c9 100%);
    padding: 20px;
    border-radius: 12px;
    margin: 20px 0;
    border-left: 4px solid #4caf50;
}

.success-box strong {
    color: #2e7d32;
    display: block;
    margin-bottom: 8px;
    font-size: 1.1em;
}

pre {
    background: #2d3748;
    color: #f7fafc;
    padding: 20px;
    border-radius: 12px;
    overflow-x: auto;
    margin: 20px 0;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

code {
    font-family: 'Courier New', monospace;
    font-size: 0.95em;
    line-height: 1.6;
}

.keyword {
    color: #c792ea;
}

.function {
    color: #82aaff;
}

.string {
    color: #c3e88d;
}

.comment {
    color: #546e7a;
    font-style: italic;
}

.highlight {
    background: linear-gradient(135deg, #ffeaa7 0%, #fdcb6e 100%);
    padding: 3px 8px;
    border-radius: 5px;
    font-weight: 600;
}

.step-card {
    background: white;
    padding: 20px;
    border-radius: 12px;
    margin: 15px 0;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    border-left: 4px solid #667eea;
}

.step-number {
    display: inline-block;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    text-align: center;
    line-height: 35px;
    font-weight: bold;
    margin-right: 10px;
    font-size: 1.1em;
}

.exercise-section {
    background: linear-gradient(135deg, #f3e5f5 0%, #e1bee7 100%);
    padding: 30px;
    border-radius: 15px;
    margin-top: 40px;
}

.exercise-section h2 {
    color: #6a1b9a;
    margin-bottom: 20px;
}

.exercise-card {
    background: white;
    padding: 20px;
    border-radius: 12px;
    margin: 15px 0;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.exercise-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.3);
}

.exercise-number {
    display: inline-block;
    background: #6a1b9a;
    color: white;
    padding: 5px 15px;
    border-radius: 20px;
    font-weight: bold;
    margin-bottom: 10px;
}

.navigation {
    display: flex;
    justify-content: space-between;
    margin-top: 40px;
    gap: 20px;
}

.nav-button {
    flex: 1;
    padding: 15px 25px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-decoration: none;
    border-radius: 12px;
    text-align: center;
    font-weight: 600;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.nav-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.5);
}

.flow-diagram {
    background: white;
    padding: 25px;
    border-radius: 12px;
    margin: 20px 0;
    text-align: center;
}

.flow-step {
    display: inline-block;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 12px 20px;
    border-radius: 8px;
    margin: 5px;
    font-weight: 600;
}

.flow-arrow {
    display: inline-block;
    font-size: 1.5em;
    color: #667eea;
    margin: 0 10px;
}

@media (max-width: 768px) {
    .container {
        padding: 25px 20px;
    }

    h1 {
        font-size: 1.8em;
    }

    h2 {
        font-size: 1.4em;
    }

    .section {
        padding: 20px 15px;
    }

    pre {
        padding: 15px;
        font-size: 0.85em;
    }

    .navigation {
        flex-direction: column;
    }

    .flow-diagram {
        padding: 15px;
    }

    .flow-step {
        display: block;
        margin: 10px 0;
    }

    .flow-arrow {
        display: block;
        transform: rotate(90deg);
    }
}