:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --text-color: #1f2937;
    --text-light: #6b7280;
    --bg-color: #ffffff;
    --bg-light: #f9fafb;
    --bg-section: #f3f4f6;
    --border-color: #e5e7eb;
    --max-width: 1100px;
    --content-width: 760px;
}

.de_iv_adv {
    width: 100%;
    height: auto;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 5px 0;
    background-color: #F8F8F8;
    margin: 10px 0 0px;
}


/* 底部广告位 */

.postionFixed {
    width: 100%;
    min-height: 60px;
    position: fixed;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #F8F8F8;
    right: 0;
    left: 0;
    bottom: 0;
    z-index: 9999;
}

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

ul {
    list-style: none;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    font-size: 1rem;
    line-height: 1.7;
    color: var(--text-color);
    background-color: var(--bg-color);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

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

a:hover {
    color: var(--primary-dark);
}

.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 1.25rem;
}

.content-container {
    max-width: var(--content-width);
    margin: 0 auto;
}

h1,
h2,
h3,
h4 {
    color: var(--text-color);
    line-height: 1.3;
    margin-bottom: 1rem;
    font-weight: 600;
}

h1 {
    font-size: 2rem;
}

h2 {
    font-size: 1.5rem;
}

h3 {
    font-size: 1.25rem;
}

h4 {
    font-size: 1.125rem;
}

p {
    margin-bottom: 1rem;
}

.site-header {
    background: var(--bg-color);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    padding-bottom: 1rem;
}

.logo a {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-list {
    display: flex;
    gap: 1.5rem;
    list-style: none;
}

.nav-list a {
    color: var(--text-color);
    font-weight: 500;
    font-size: 0.9375rem;
}

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

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-btn span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--text-color);
    margin: 5px 0;
}

.hero-banner {
    background: var(--bg-section);
    padding: 3rem 0;
    border-bottom: 1px solid var(--border-color);
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: center;
}

.hero-text h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.hero-text p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
}

.hero-image img {
    border-radius: 8px;
}

.btn {
    display: inline-block;
    background: var(--primary-color);
    color: #fff;
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    font-weight: 500;
    font-size: 0.9375rem;
}

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

.section {
    padding: 3rem 0;
}

.section-title {
    text-align: center;
    margin-bottom: 2rem;
}

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

.tutorial-card {
    background: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    overflow: hidden;
}

.tutorial-card:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.card-image {
    aspect-ratio: 16/9;
    background: var(--bg-section);
}

.card-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.card-content {
    padding: 1.25rem;
}

.card-content h3 {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
}

.card-content p {
    color: var(--text-light);
    font-size: 0.9375rem;
    margin-bottom: 1rem;
}

.card-meta {
    display: flex;
    gap: 1rem;
    font-size: 0.8125rem;
    color: var(--text-light);
}

.site-footer {
    background: var(--text-color);
    color: #d1d5db;
    padding: 3rem 0 1.5rem;
}

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

.footer-brand p {
    color: #9ca3af;
    font-size: 0.875rem;
}

.footer-links h4 {
    color: #fff;
    font-size: 0.9375rem;
    margin-bottom: 1rem;
}

.footer-links ul {
    list-style: none;
}

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

.footer-links a {
    color: #9ca3af;
    font-size: 0.875rem;
}

.footer-links a:hover {
    color: #fff;
}

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 1.5rem;
    text-align: center;
    font-size: 0.8125rem;
    color: #6b7280;
}

.page-header {
    background: var(--bg-section);
    padding: 2rem 0;
    border-bottom: 1px solid var(--border-color);
}

.page-header h1 {
    margin-bottom: 0.5rem;
}

.page-content {
    padding: 2.5rem 0;
}

.lesson-nav {
    display: flex;
    justify-content: space-between;
    margin-top: 2.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

.lesson-nav a {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 500;
}

.lesson-list {
    list-style: none;
}

.lesson-list li {
    border-bottom: 1px solid var(--border-color);
}

.lesson-list a {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    color: var(--text-color);
}

.lesson-list a:hover {
    color: var(--primary-color);
}

.lesson-number {
    color: var(--text-light);
    font-size: 0.875rem;
}

.lesson-section {
    margin-bottom: 2rem;
}

.lesson-section h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--border-color);
}

.lesson-section h3 {
    font-size: 1.125rem;
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
}

.lesson-section ul,
.lesson-section ol {
    margin-bottom: 1rem;
    padding-left: 1.25rem;
}

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

.lesson-image {
    margin: 1.5rem 0;
    text-align: center;
}

.lesson-image img {
    max-width: 100%;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    margin: 0 auto;
}

.lesson-image figcaption {
    margin-top: 0.75rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.code-block {
    background: #1e293b;
    border-radius: 6px;
    margin: 1.25rem 0;
    overflow: hidden;
}

.code-header {
    background: #0f172a;
    padding: 0.5rem 1rem;
    font-size: 0.75rem;
    color: #94a3b8;
    font-family: monospace;
}

.code-block pre {
    padding: 1rem;
    overflow-x: auto;
    margin: 0;
}

.code-block code {
    font-family: 'Consolas', monospace;
    font-size: 0.875rem;
    color: #000;
    line-height: 1.5;
}

code {
    background: var(--bg-section);
    padding: 0.125rem 0.375rem;
    border-radius: 4px;
    font-family: 'Consolas', monospace;
    font-size: 0.875em;
}

.info-box {
    padding: 1rem 1.25rem;
    border-radius: 6px;
    margin: 1.25rem 0;
    border-left: 4px solid;
}

.info-box.note {
    background: #eff6ff;
    border-color: var(--primary-color);
}

.info-box.warning {
    background: #fffbeb;
    border-color: #f59e0b;
}

.info-box strong {
    display: block;
    margin-bottom: 0.375rem;
}

.search-container {
    max-width: 600px;
    margin: 0 auto;
}

.search-form {
    display: flex;
    gap: 0.75rem;
}

.search-input {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
}

.search-btn {
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: #fff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 500;
}

.legal-content h2 {
    margin-top: 2rem;
    margin-bottom: 1rem;
}

.legal-content p {
    margin-bottom: 1rem;
    color: var(--text-light);
}

.contact-form {
    max-width: 500px;
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.375rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
}

.form-group textarea {
    min-height: 120px;
    resize: vertical;
}

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }

    h1 {
        font-size: 1.625rem;
    }

    h2 {
        font-size: 1.375rem;
    }

    .mobile-menu-btn {
        display: block;
    }

    .nav-list {
        position: fixed;
        top: 60px;
        height: 100vh;
        left: 0;
        right: 0;
        background: var(--bg-color);
        flex-direction: column;
        padding: 1rem;
        gap: 0;
        border-bottom: 1px solid var(--border-color);
        display: none;
    }

    .nav-list.active {
        display: flex;
    }

    .nav-list li {
        border-bottom: 1px solid var(--border-color);
    }

    .nav-list a {
        display: block;
        padding: 0.875rem 0;
    }

    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-image {
        order: -1;
    }

    .footer-content {
        grid-template-columns: 1fr 1fr;
        gap: 1.5rem;
    }

    .lesson-nav {
        flex-direction: column;
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .hero-banner {
        padding: 2rem 0;
    }

    .section {
        padding: 2rem 0;
    }

    .footer-content {
        grid-template-columns: 1fr;
    }

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