/* ============================================================
   半导体行业交流论坛 - 主样式表
   ============================================================ */

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --info: #3b82f6;
    --dark: #1e293b;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;
    --radius: 8px;
    --radius-lg: 12px;
    --shadow: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,.08), 0 4px 6px -2px rgba(0,0,0,.04);
    --transition: all .2s ease;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: var(--gray-800);
    background: var(--gray-50);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

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

/* ============================================================
   Header
   ============================================================ */
.site-header {
    background: #fff;
    border-bottom: 1px solid var(--gray-200);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow);
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}
.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 20px;
    font-weight: 700;
    color: var(--dark);
    text-decoration: none;
}
.logo i { color: var(--primary); font-size: 28px; }

.main-nav {
    display: flex;
    align-items: center;
    gap: 6px;
}
.main-nav a {
    padding: 8px 14px;
    color: var(--gray-600);
    text-decoration: none;
    border-radius: var(--radius);
    font-size: 14px;
    transition: var(--transition);
}
.main-nav a:hover, .main-nav a.active {
    color: var(--primary);
    background: var(--gray-100);
}
.main-nav .btn { padding: 8px 18px; }

.user-dropdown {
    position: relative;
    display: inline-block;
}
.user-btn {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 12px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    background: #fff;
    cursor: pointer;
    font-size: 14px;
}
.user-btn:hover { border-color: var(--primary); }
.dropdown-menu {
    display: none;
    position: absolute;
    right: 0;
    top: 100%;
    min-width: 180px;
    background: #fff;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    z-index: 50;
    padding: 4px;
}
.user-dropdown:hover .dropdown-menu { display: block; }
.dropdown-menu a {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 14px;
    color: var(--gray-700);
    text-decoration: none;
    font-size: 14px;
    border-radius: 4px;
}
.dropdown-menu a:hover { background: var(--gray-100); color: var(--primary); }
.dropdown-menu hr { margin: 4px 0; border: none; border-top: 1px solid var(--gray-200); }

.mobile-menu-btn { display: none; background: none; border: none; font-size: 24px; cursor: pointer; color: var(--gray-700); }

/* ============================================================
   Buttons
   ============================================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 10px 22px;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    text-decoration: none;
    transition: var(--transition);
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-1px); }
.btn-outline { background: transparent; border: 1px solid var(--gray-300); color: var(--gray-700); }
.btn-outline:hover { border-color: var(--primary); color: var(--primary); }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { background: #dc2626; }
.btn-sm { padding: 6px 14px; font-size: 13px; }
.btn-block { width: 100%; justify-content: center; }
.btn-success { background: var(--success); color: #fff; }

/* ============================================================
   Hero Section
   ============================================================ */
.hero {
    background: linear-gradient(135deg, #1e40af 0%, #3b82f6 50%, #60a5fa 100%);
    color: #fff;
    padding: 80px 0;
    text-align: center;
}
.hero-content h1 { font-size: 40px; margin-bottom: 12px; }
.hero-content p { font-size: 18px; opacity: .9; margin-bottom: 24px; }
.hero-stats { display: flex; justify-content: center; gap: 32px; }
.hero-stats span { display: flex; align-items: center; gap: 8px; font-size: 16px; }

/* ============================================================
   Section Titles
   ============================================================ */
.section-title {
    font-size: 24px;
    margin-bottom: 24px;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--dark);
}
.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 24px;
}
.section-header select {
    padding: 8px 14px;
    border: 1px solid var(--gray-300);
    border-radius: var(--radius);
    font-size: 14px;
    background: #fff;
}

/* ============================================================
   Category Grid
   ============================================================ */
.categories-section { padding: 60px 0; }
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 20px;
}
.category-card {
    display: flex;
    gap: 16px;
    padding: 20px;
    background: #fff;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    text-decoration: none;
    transition: var(--transition);
}
.category-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }
.category-icon {
    width: 56px;
    height: 56px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    color: #fff;
    flex-shrink: 0;
}
.category-info h3 { font-size: 16px; color: var(--dark); margin-bottom: 6px; }
.category-info p { font-size: 13px; color: var(--gray-500); line-height: 1.5; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.post-count { font-size: 12px; color: var(--gray-400); margin-top: 8px; display: inline-block; }

/* ============================================================
   Post List
   ============================================================ */
.posts-section { padding: 40px 0 60px; background: #fff; }
.post-list { display: flex; flex-direction: column; gap: 16px; }
.post-card {
    padding: 24px;
    background: #fff;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    transition: var(--transition);
}
.post-card:hover { border-color: var(--primary); box-shadow: var(--shadow); }
.post-card.pinned {
    border-left: 4px solid var(--danger);
    background: linear-gradient(135deg, #fef2f2, #fff);
}
.pinned-badge {
    font-size: 12px;
    color: var(--danger);
    margin-bottom: 8px;
    font-weight: 600;
}
.post-meta {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 13px;
    color: var(--gray-500);
    margin-bottom: 10px;
    flex-wrap: wrap;
}
.post-meta span { display: flex; align-items: center; gap: 4px; }
.post-category { font-weight: 600; }
.post-title {
    font-size: 20px;
    margin-bottom: 10px;
}
.post-title a { color: var(--dark); text-decoration: none; }
.post-title a:hover { color: var(--primary); }
.post-excerpt {
    font-size: 14px;
    color: var(--gray-600);
    margin-bottom: 14px;
    line-height: 1.6;
}
.post-footer {
    display: flex;
    align-items: center;
    gap: 16px;
    font-size: 13px;
    color: var(--gray-400);
}
.post-tags { display: flex; gap: 6px; flex-wrap: wrap; margin-left: auto; }
.tag {
    padding: 2px 10px;
    background: var(--gray-100);
    border-radius: 20px;
    font-size: 12px;
    color: var(--gray-600);
}

/* ============================================================
   Post Detail
   ============================================================ */
.post-detail { padding: 40px 0; background: #fff; }
.post-header { margin-bottom: 32px; }
.post-meta-top {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}
.post-category-badge {
    padding: 4px 14px;
    border-radius: 20px;
    color: #fff;
    font-size: 13px;
    text-decoration: none;
}
.post-detail .post-title { font-size: 32px; line-height: 1.3; }
.post-author-info {
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 20px 0;
}
.post-author-info .avatar { width: 44px; height: 44px; border-radius: 50%; object-fit: cover; }
.author-name { font-weight: 600; font-size: 15px; display: block; }
.post-date { font-size: 13px; color: var(--gray-500); }
.post-content {
    font-size: 16px;
    line-height: 1.8;
    color: var(--gray-700);
}
.post-content h2 {
    font-size: 24px;
    margin: 32px 0 16px;
    color: var(--dark);
    padding-bottom: 8px;
    border-bottom: 1px solid var(--gray-200);
}
.post-content h3 { font-size: 20px; margin: 24px 0 12px; color: var(--dark); }
.post-content p { margin-bottom: 16px; }
.post-content ul, .post-content ol { margin: 0 0 16px 24px; }
.post-content li { margin-bottom: 8px; }
.post-content table { width: 100%; border-collapse: collapse; margin: 16px 0; }
.post-content th, .post-content td { padding: 10px 14px; border: 1px solid var(--gray-200); text-align: left; }
.post-content th { background: var(--gray-100); font-weight: 600; }

/* ============================================================
   Comments
   ============================================================ */
.comments-section { margin-top: 48px; padding-top: 32px; border-top: 1px solid var(--gray-200); }
.comment-form { margin-bottom: 32px; padding: 24px; background: var(--gray-50); border-radius: var(--radius-lg); }
.comment-form h3 { margin-bottom: 16px; font-size: 18px; }
.comment-list { display: flex; flex-direction: column; gap: 16px; }
.comment-item { display: flex; gap: 14px; padding: 16px; border: 1px solid var(--gray-200); border-radius: var(--radius); }
.comment-avatar img { width: 40px; height: 40px; border-radius: 50%; object-fit: cover; }
.comment-avatar .avatar-placeholder { width: 40px; height: 40px; border-radius: 50%; background: var(--gray-200); color: var(--gray-500); display: flex; align-items: center; justify-content: center; font-size: 16px; font-weight: 600; flex-shrink: 0; }
.comment-body { flex: 1; }
.comment-meta { margin-bottom: 6px; }
.comment-author { font-size: 14px; }
.comment-reply-to { font-size: 12px; color: var(--primary); margin-left: 8px; }
.comment-reply-to i { font-size: 10px; }
.comment-date { font-size: 12px; color: var(--gray-400); margin-left: 10px; }
.comment-content { font-size: 14px; color: var(--gray-700); }
.btn-reply {
    margin-top: 8px;
    padding: 4px 12px;
    background: none;
    border: 1px solid var(--gray-300);
    border-radius: 4px;
    cursor: pointer;
    font-size: 12px;
    color: var(--gray-600);
}
.btn-reply:hover { border-color: var(--primary); color: var(--primary); }

/* ============================================================
   Auth Pages
   ============================================================ */
.auth-page { background: linear-gradient(135deg, #e0e7ff, #f0f4ff); }
.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: calc(100vh - 64px);
    padding: 40px 20px;
}
.auth-card {
    width: 100%;
    max-width: 420px;
    background: #fff;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 40px;
}
.auth-header { text-align: center; margin-bottom: 32px; }
.auth-icon { font-size: 48px; color: var(--primary); margin-bottom: 16px; }
.auth-header h1 { font-size: 28px; margin-bottom: 8px; }
.auth-header p { color: var(--gray-500); }
.auth-footer { text-align: center; margin-top: 24px; font-size: 14px; color: var(--gray-500); }
.auth-footer a { color: var(--primary); text-decoration: none; font-weight: 600; }

/* ============================================================
   Forms
   ============================================================ */
.form-group { margin-bottom: 18px; }
.form-group label { display: block; font-size: 14px; font-weight: 500; margin-bottom: 6px; color: var(--gray-700); }
.form-group input, .form-group textarea, .form-group select {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--gray-300);
    border-radius: var(--radius);
    font-size: 14px;
    transition: var(--transition);
}
.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37,99,235,.1);
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.required { color: var(--danger); }
.checkbox-label {
    display: flex !important;
    align-items: center;
    gap: 8px;
    cursor: pointer;
}
.checkbox-label input[type="checkbox"] {
    width: auto;
}

/* ============================================================
   Alerts
   ============================================================ */
.alert {
    padding: 14px 18px;
    border-radius: var(--radius);
    font-size: 14px;
    margin-bottom: 18px;
}
.alert-error { background: #fef2f2; color: #dc2626; border: 1px solid #fecaca; }
.alert-success { background: #f0fdf4; color: #16a34a; border: 1px solid #bbf7d0; }
.alert-info { background: #eff6ff; color: #2563eb; border: 1px solid #bfdbfe; }

/* ============================================================
   Page Banner
   ============================================================ */
.page-banner { padding: 60px 0; }
.banner-content { display: flex; align-items: center; gap: 24px; }
.banner-icon {
    width: 72px;
    height: 72px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 32px;
    color: #fff;
    flex-shrink: 0;
}
.banner-text h1 { font-size: 32px; margin-bottom: 8px; }
.banner-text p { font-size: 15px; color: var(--gray-600); }
.banner-stat { font-size: 14px; color: var(--gray-500); margin-top: 8px; display: inline-block; }

/* ============================================================
   Empty State
   ============================================================ */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--gray-400);
}
.empty-state i { font-size: 48px; margin-bottom: 16px; }
.empty-state p { font-size: 16px; }

/* ============================================================
   Pagination
   ============================================================ */
.pagination { margin-top: 32px; display: flex; justify-content: center; }
.pagination ul { display: flex; gap: 4px; list-style: none; }
.pagination a, .pagination span {
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 38px;
    height: 38px;
    padding: 0 12px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    text-decoration: none;
    font-size: 14px;
    color: var(--gray-600);
    transition: var(--transition);
}
.pagination a:hover { border-color: var(--primary); color: var(--primary); }
.pagination .active span { background: var(--primary); color: #fff; border-color: var(--primary); }

/* ============================================================
   Avatar
   ============================================================ */
.avatar { width: 32px; height: 32px; border-radius: 50%; object-fit: cover; }
.avatar-small { width: 28px; height: 28px; border-radius: 50%; object-fit: cover; }

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
    background: var(--gray-900);
    color: var(--gray-400);
    padding: 60px 0 0;
    margin-top: auto;
}
.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 2fr;
    gap: 40px;
    margin-bottom: 32px;
}
.footer-brand h3 { color: #fff; margin-bottom: 12px; font-size: 20px; }
.footer-brand p { font-size: 14px; line-height: 1.6; }
.footer-links h4, .footer-categories h4 { color: #fff; margin-bottom: 16px; font-size: 16px; }
.footer-links a, .footer-categories a {
    display: block;
    color: var(--gray-400);
    text-decoration: none;
    font-size: 14px;
    padding: 4px 0;
    transition: var(--transition);
}
.footer-links a:hover, .footer-categories a:hover { color: #fff; }
.footer-bottom {
    border-top: 1px solid var(--gray-700);
    padding: 20px 0;
    text-align: center;
    font-size: 13px;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 768px) {
    .hero { padding: 60px 20px; }
    .hero-content h1 { font-size: 28px; }
    .hero-stats { flex-direction: column; gap: 12px; align-items: center; }
    .category-grid { grid-template-columns: 1fr; }
    .footer-content { grid-template-columns: 1fr; }
    .mobile-menu-btn { display: block; }
    .main-nav {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: #fff;
        flex-direction: column;
        padding: 16px;
        border-bottom: 1px solid var(--gray-200);
        box-shadow: var(--shadow-lg);
    }
    .main-nav.show { display: flex; }
    .form-row { grid-template-columns: 1fr; }
    .banner-content { flex-direction: column; text-align: center; }
    .post-detail .post-title { font-size: 24px; }
    .auth-card { padding: 24px; }
}