/* Python 学习网 - 样式表 */

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

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

/* Header */
header {
    background: rgba(255, 255, 255, 0.95);
    padding: 30px 0;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

header h1 {
    color: #306998;
    font-size: 2.5em;
    text-align: center;
}

.subtitle {
    text-align: center;
    color: #666;
    margin-top: 10px;
    font-size: 1.2em;
}

.back-link {
    display: inline-block;
    margin-bottom: 15px;
    color: #667eea;
    text-decoration: none;
}

.back-link:hover {
    text-decoration: underline;
}

/* Main Content */
main {
    padding: 40px 20px;
}

.intro {
    background: white;
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 40px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.intro h2 {
    color: #306998;
    margin-bottom: 15px;
}

/* Categories */
.category {
    background: white;
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.category h2 {
    color: #ffd343;
    background: #306998;
    padding: 10px 20px;
    border-radius: 5px;
    margin-bottom: 20px;
    display: inline-block;
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.lesson-card {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    padding: 25px;
    border-radius: 10px;
    text-decoration: none;
    color: #333;
    transition: transform 0.3s, box-shadow 0.3s;
    border-left: 4px solid #306998;
}

.lesson-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
}

.lesson-card h3 {
    color: #306998;
    margin-bottom: 10px;
}

.lesson-card p {
    color: #666;
    margin-bottom: 15px;
    font-size: 0.95em;
}

.start-btn {
    display: inline-block;
    background: #306998;
    color: white;
    padding: 8px 20px;
    border-radius: 20px;
    font-size: 0.9em;
    transition: background 0.3s;
}

.lesson-card:hover .start-btn {
    background: #ffd343;
    color: #333;
}

/* Features */
.features {
    background: white;
    padding: 40px 30px;
    border-radius: 10px;
    margin-top: 40px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.features h2 {
    color: #306998;
    text-align: center;
    margin-bottom: 30px;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
}

.feature {
    text-align: center;
    padding: 20px;
}

.feature-icon {
    font-size: 3em;
    margin-bottom: 15px;
}

.feature h3 {
    color: #306998;
    margin-bottom: 10px;
}

.feature p {
    color: #666;
}

/* Tutorial Page */
.breadcrumb {
    margin-bottom: 20px;
    color: #666;
}

.breadcrumb a {
    color: #667eea;
    text-decoration: none;
}

.breadcrumb a:hover {
    text-decoration: underline;
}

.lesson-content {
    background: white;
    padding: 40px;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.lesson-content h2 {
    color: #306998;
    margin: 30px 0 15px 0;
    padding-bottom: 10px;
    border-bottom: 2px solid #ffd343;
}

.lesson-content h2:first-child {
    margin-top: 0;
}

.lesson-content h3 {
    color: #667eea;
    margin: 25px 0 15px 0;
}

.lesson-content p {
    margin-bottom: 15px;
}

.lesson-content ul {
    margin: 15px 0;
    padding-left: 30px;
}

.lesson-content li {
    margin-bottom: 8px;
}

.lesson-content pre {
    background: #282c34;
    color: #abb2bf;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 15px 0;
    font-family: "Fira Code", "Consolas", monospace;
    font-size: 0.95em;
}

.lesson-content code {
    font-family: "Fira Code", "Consolas", monospace;
}

.lesson-content :not(pre) > code {
    background: #f0f0f0;
    padding: 2px 6px;
    border-radius: 4px;
    color: #e83e8c;
}

/* Exercise Box */
.exercise-box {
    background: white;
    padding: 30px;
    border-radius: 10px;
    margin-bottom: 30px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    border-top: 4px solid #ffd343;
}

.exercise-box h2 {
    color: #306998;
    margin-bottom: 15px;
}

.exercise-task {
    background: #fff3cd;
    padding: 15px 20px;
    border-radius: 8px;
    border-left: 4px solid #ffc107;
    margin-bottom: 20px;
    font-weight: 500;
}

.code-editor {
    margin-top: 20px;
}

.code-editor label {
    display: block;
    margin-bottom: 10px;
    font-weight: 500;
    color: #333;
}

.code-editor textarea {
    width: 100%;
    font-family: "Fira Code", "Consolas", monospace;
    font-size: 0.95em;
    padding: 15px;
    border: 2px solid #ddd;
    border-radius: 8px;
    resize: vertical;
    transition: border-color 0.3s;
}

.code-editor textarea:focus {
    outline: none;
    border-color: #667eea;
}

#run-btn {
    margin-top: 15px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    padding: 12px 30px;
    border-radius: 8px;
    font-size: 1em;
    cursor: pointer;
    transition: transform 0.2s, box-shadow 0.2s;
}

#run-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.output {
    margin-top: 20px;
    padding: 15px;
    background: #282c34;
    color: #98c379;
    border-radius: 8px;
    font-family: "Fira Code", "Consolas", monospace;
    min-height: 60px;
    white-space: pre-wrap;
}

/* Lesson Navigation */
.lesson-nav {
    display: flex;
    justify-content: space-between;
    gap: 20px;
    margin-top: 30px;
}

.nav-btn {
    background: white;
    color: #667eea;
    padding: 12px 25px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: background 0.3s, color 0.3s;
    border: 2px solid #667eea;
}

.nav-btn:hover {
    background: #667eea;
    color: white;
}

/* Footer */
footer {
    background: rgba(0, 0, 0, 0.2);
    color: white;
    padding: 20px 0;
    margin-top: 40px;
}

footer p {
    text-align: center;
}

/* Responsive */
@media (max-width: 768px) {
    header h1 {
        font-size: 1.8em;
    }

    .lessons-grid {
        grid-template-columns: 1fr;
    }

    .features-grid {
        grid-template-columns: 1fr;
    }

    .lesson-content {
        padding: 20px;
    }

    .lesson-nav {
        flex-direction: column;
    }

    .nav-btn {
        text-align: center;
    }
}