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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
    background: linear-gradient(135deg, #e8f5e9 0%, #c8e6c9 100%);
    min-height: 100vh;
    padding: 40px 20px;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
    padding: 60px;
}

.back-link {
    display: inline-block;
    color: #43a047;
    text-decoration: none;
    margin-bottom: 30px;
    font-size: 16px;
    transition: all 0.3s;
}

.back-link:hover {
    color: #2e7d32;
    transform: translateX(-5px);
}

h1 {
    color: #2c3e50;
    font-size: 42px;
    margin-bottom: 10px;
    border-bottom: 4px solid #66bb6a;
    padding-bottom: 15px;
}

h1 i {
    margin-right: 12px;
    color: #43a047;
}

.lesson-meta {
    color: #7f8c8d;
    font-size: 16px;
    margin-bottom: 40px;
}

h2 {
    color: #34495e;
    font-size: 32px;
    margin-top: 40px;
    margin-bottom: 20px;
    border-left: 5px solid #66bb6a;
    padding-left: 15px;
}

h3 {
    color: #34495e;
    font-size: 24px;
    margin-top: 30px;
    margin-bottom: 15px;
}

h4 {
    color: #7f8c8d;
    font-size: 18px;
    margin-top: 20px;
    margin-bottom: 10px;
}

p, li {
    line-height: 1.8;
    color: #2c3e50;
    margin-bottom: 12px;
    font-size: 16px;
}

ul, ol {
    margin-left: 30px;
    margin-bottom: 20px;
}

li {
    margin-bottom: 8px;
}

strong {
    color: #43a047;
    font-weight: 600;
}

code {
    background: #f8f9fa;
    padding: 3px 8px;
    border-radius: 4px;
    font-family: 'Consolas', 'Monaco', monospace;
    color: #e74c3c;
    font-size: 14px;
}

pre {
    background: #282c34;
    padding: 20px;
    border-radius: 10px;
    overflow-x: auto;
    margin: 25px 0;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

pre code {
    background: none;
    color: #abb2bf;
    padding: 0;
    font-size: 14px;
    line-height: 1.6;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 25px 0;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    border-radius: 10px;
    overflow: hidden;
}

table th {
    background: linear-gradient(135deg, #66bb6a 0%, #43a047 100%);
    color: white;
    padding: 15px;
    text-align: left;
    font-weight: 600;
}

table td {
    padding: 15px;
    border-bottom: 1px solid #ecf0f1;
}

table tr:hover {
    background: #f8f9fa;
}

table tr:last-child td {
    border-bottom: none;
}

.highlight-box {
    background: linear-gradient(135deg, #fff3cd 0%, #ffe69c 100%);
    border-left: 5px solid #ffc107;
    padding: 20px;
    margin: 25px 0;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
}

.highlight-box h4 i,
.info-box h4 i,
.warning-box h4 i,
.success-box h4 i {
    margin-right: 8px;
}

.info-box {
    background: linear-gradient(135deg, #d1ecf1 0%, #bee5eb 100%);
    border-left: 5px solid #17a2b8;
    padding: 20px;
    margin: 25px 0;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
}

.warning-box {
    background: linear-gradient(135deg, #f8d7da 0%, #f5c6cb 100%);
    border-left: 5px solid #dc3545;
    padding: 20px;
    margin: 25px 0;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
}

.success-box {
    background: linear-gradient(135deg, #d4edda 0%, #c3e6cb 100%);
    border-left: 5px solid #28a745;
    padding: 20px;
    margin: 25px 0;
    border-radius: 10px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.1);
}

.algo-viz {
    background: #f8f9fa;
    border: 3px solid #66bb6a;
    border-radius: 15px;
    padding: 25px;
    margin: 30px 0;
}

.algo-viz h3 {
    color: #43a047;
    margin-top: 0;
}

#canvas-container {
    background: white;
    border-radius: 10px;
    padding: 20px;
    min-height: 350px;
    margin: 20px 0;
}

.controls {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
    margin-top: 20px;
}

.controls button {
    padding: 12px 24px;
    background: linear-gradient(135deg, #66bb6a 0%, #43a047 100%);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    transition: all 0.3s;
    box-shadow: 0 3px 10px rgba(67, 160, 71, 0.3);
}

.controls button:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(67, 160, 71, 0.5);
}

.controls button:active {
    transform: translateY(-1px);
}

.formula {
    background: #f8f9fa;
    padding: 20px;
    border-radius: 10px;
    margin: 20px 0;
    text-align: center;
    box-shadow: 0 3px 10px rgba(0,0,0,0.05);
}

::-webkit-scrollbar {
    width: 10px;
    height: 10px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 5px;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(135deg, #66bb6a 0%, #43a047 100%);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(135deg, #43a047 0%, #66bb6a 100%);
}

@media (max-width: 768px) {
    .container {
        padding: 30px 20px;
    }
    
    h1 {
        font-size: 32px;
    }
    
    h2 {
        font-size: 24px;
    }
    
    h3 {
        font-size: 20px;
    }
}