:root {
    --primary-color: #4a90e2;
    --secondary-color: #f5f5f5;
    --text-color: #333;
    --light-gray: #e0e0e0;
    --warm-white: #fafafa;
}

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

body {
    font-family: 'Arial', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--warm-white);
}

/* Header and Navigation */
header {
    background-color: white;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

.main-nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo a {
    font-size: 1.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: bold;
}

.search-container {
    display: flex;
    gap: 0.5rem;
}

.search-container input {
    padding: 0.5rem;
    border: 1px solid var(--light-gray);
    border-radius: 4px;
    width: 300px;
}

.search-container button {
    padding: 0.5rem 1rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-color);
    text-decoration: none;
}

/* Dropdown Menu */
.dropdown {
    position: relative;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: white;
    min-width: 200px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
    border-radius: 4px;
}

.dropdown:hover .dropdown-content {
    display: block;
}

.dropdown-content li {
    list-style: none;
}

.dropdown-content a {
    padding: 0.5rem 1rem;
    display: block;
}

.dropdown-content a:hover {
    background-color: var(--secondary-color);
}

/* Main Content */
main {
    margin-top: 80px;
    padding: 2rem;
}

.hero {
    text-align: center;
    padding: 4rem 2rem;
    background-color: var(--secondary-color);
    border-radius: 8px;
    margin-bottom: 3rem;
}

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.subtitle {
    font-size: 1.2rem;
    color: #666;
}

/* Category Grid */
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.category-card {
    background-color: white;
    padding: 1.5rem;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.category-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.button {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 4px;
    margin-top: 1rem;
}

/* Writing Tips Section */
.writing-tips {
    background-color: white;
    padding: 3rem;
    border-radius: 8px;
    margin: 3rem 0;
    text-align: center;
}

.tips-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.tip {
    padding: 1rem;
}

/* Footer */
footer {
    background-color: var(--secondary-color);
    padding: 3rem 2rem 1rem;
    margin-top: 4rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

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

.footer-section a {
    color: var(--text-color);
    text-decoration: none;
    display: block;
    padding: 0.3rem 0;
}

.footer-bottom {
    text-align: center;
    margin-top: 2rem;
    padding-top: 1rem;
    border-top: 1px solid var(--light-gray);
}

/* Responsive Design */
@media (max-width: 768px) {
    header {
        position: relative;
    }

    .main-nav {
        flex-direction: column;
        gap: 1rem;
        padding: 0.5rem;
    }

    .search-container {
        width: 100%;
    }

    .search-container input {
        width: 100%;
    }

    .nav-links {
        flex-direction: column;
        width: 100%;
        text-align: center;
        gap: 0.5rem;
    }

    .dropdown-content {
        position: static;
        box-shadow: none;
        background-color: var(--secondary-color);
        margin: 0.5rem 0;
    }

    main {
        margin-top: 0;
    }

    .dropdown:hover .dropdown-content {
        display: block;
        width: 100%;
    }

    .dropdown-content a {
        padding: 0.5rem;
    }
}

/* 广告容器样式 */
.ad-container {
    background-color: #f5f5f5;
    padding: 1rem;
    margin: 1rem 0;
    text-align: center;
    border-radius: 4px;
}

.ad-label {
    font-size: 0.8rem;
    color: #666;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
}

/* 顶部广告 */
.ad-top {
    width: 100%;
    max-width: 728px;
    margin: 1rem auto;
}

/* 内联广告 */
.ad-inline {
    grid-column: span 2;
    margin: 1rem 0;
}

/* 侧边栏广告 */
.ad-sidebar {
    position: sticky;
    top: 1rem;
}

/* 底部广告 */
.ad-bottom {
    width: 100%;
    max-width: 728px;
    margin: 2rem auto;
}

/* 内容布局 */
.content-wrapper {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.main-content {
    min-width: 0;
}

.sidebar {
    width: 300px;
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .content-wrapper {
        grid-template-columns: 1fr;
    }

    .sidebar {
        width: 100%;
    }

    .ad-sidebar {
        position: static;
    }
}

@media (max-width: 768px) {
    .ad-inline {
        grid-column: span 1;
    }
}