/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #4A90E2;
    --primary-dark: #357ABD;
    --secondary-color: #50C878;
    --text-dark: #2C3E50;
    --text-light: #7F8C8D;
    --bg-light: #F8F9FA;
    --bg-white: #FFFFFF;
    --border-color: #E1E8ED;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 16px rgba(0, 0, 0, 0.15);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    color: var(--text-dark);
    line-height: 1.6;
    background-color: var(--bg-light);
}

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

/* Header */
.header {
    background: var(--bg-white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
}

.logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
}

.nav {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
}

.auth-buttons {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    position: relative;
    cursor: pointer;
}

.user-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
    cursor: pointer;
}

.user-menu #userName {
    cursor: pointer;
    font-weight: 500;
}

.user-dropdown {
    display: none;
    position: absolute;
    top: 100%;
    right: 0;
    background: var(--bg-white);
    box-shadow: var(--shadow-hover);
    border-radius: 8px;
    padding: 0.5rem 0;
    margin-top: 0.5rem;
    min-width: 180px;
    z-index: 1001;
}

.user-menu.active .user-dropdown,
.user-menu:hover .user-dropdown {
    display: block;
}

.user-dropdown a {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-dark);
    text-decoration: none;
    transition: background 0.3s, color 0.3s;
}

.user-dropdown a:hover {
    background: var(--bg-light);
    color: var(--primary-color);
}

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
    font-size: 1rem;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.btn-outline {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: white;
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
}

.btn-block {
    width: 100%;
}

/* Banner */
.banner {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 4rem 0;
    text-align: center;
}

.banner-content {
    max-width: 800px;
    margin: 0 auto;
}

.banner-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.banner-subtitle {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.banner-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* Sections */
section {
    padding: 4rem 0;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--text-dark);
}

/* Posts Grid */
.posts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.post-card {
    background: var(--bg-white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s, box-shadow 0.3s;
    cursor: pointer;
}

.post-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-hover);
}

.post-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.post-content {
    padding: 1.5rem;
}

.post-category {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
    margin-bottom: 0.75rem;
}

.post-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.post-excerpt {
    color: var(--text-light);
    margin-bottom: 1rem;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.post-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-light);
}

.post-author {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.post-author-avatar {
    width: 24px;
    height: 24px;
    border-radius: 50%;
}

.post-stats {
    display: flex;
    gap: 1rem;
}

.post-tags {
    margin-top: 0.75rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag {
    background: var(--bg-light);
    color: var(--text-dark);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
}

/* Categories */
.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.category-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: transform 0.3s;
}

.category-card:hover {
    transform: translateY(-4px);
}

.category-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.category-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

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

/* Contributors */
.contributors-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 1.5rem;
}

.contributor-card {
    background: var(--bg-white);
    padding: 1.5rem;
    border-radius: 12px;
    text-align: center;
    box-shadow: var(--shadow);
}

.contributor-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    margin: 0 auto 1rem;
    object-fit: cover;
}

.contributor-name {
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.contributor-major {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 0.75rem;
}

.contributor-stats {
    display: flex;
    justify-content: space-around;
    font-size: 0.85rem;
    color: var(--text-light);
}

/* Footer */
.footer {
    background: var(--text-dark);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
}

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

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

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.3s;
}

.footer-section a:hover {
    color: white;
}

.newsletter-form {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.newsletter-form input {
    flex: 1;
    padding: 0.75rem;
    border: none;
    border-radius: 8px;
}

.social-links {
    display: flex;
    gap: 1rem;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    animation: fadeIn 0.3s;
}

.modal-content {
    background-color: var(--bg-white);
    margin: 5% auto;
    padding: 2rem;
    border-radius: 12px;
    width: 90%;
    max-width: 400px;
    position: relative;
    animation: slideDown 0.3s;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideDown {
    from {
        transform: translateY(-50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    color: var(--text-light);
}

.close:hover {
    color: var(--text-dark);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-dark);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-switch {
    text-align: center;
    margin-top: 1rem;
    color: var(--text-light);
}

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

/* Post Detail Page */
.post-detail {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.post-detail-header {
    margin-bottom: 2rem;
}

.post-detail-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.post-detail-meta {
    display: flex;
    gap: 1rem;
    align-items: center;
    color: var(--text-light);
    margin-bottom: 1rem;
}

.post-detail-content {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-dark);
}

.post-detail-content img {
    max-width: 100%;
    border-radius: 8px;
    margin: 1rem 0;
}

.post-actions {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
}

/* Comments Section */
.comments-section {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-top: 2rem;
}

.comment {
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.comment:last-child {
    border-bottom: none;
}

.comment-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.comment-content {
    color: var(--text-dark);
    margin-left: 3rem;
}

/* Write Post Page */
.write-post-form {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    max-width: 800px;
    margin: 2rem auto;
}

/* Community Posts */
.community-post {
    background: var(--bg-white);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    margin-bottom: 1rem;
}

.community-post-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.community-post-content {
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.community-post-actions {
    display: flex;
    gap: 1rem;
    align-items: center;
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }

    .nav {
        flex-wrap: wrap;
        justify-content: center;
    }

    .banner-title {
        font-size: 1.75rem;
    }

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

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