/* ===== Reset & Base ===== */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #8B5CF6;
    --primary-light: #A78BFA;
    --primary-dark: #7C3AED;
    --secondary: #EC4899;
    --accent: #F59E0B;
    --bg: #F8F5FF;
    --bg-card: #FFFFFF;
    --text: #1F2937;
    --text-light: #6B7280;
    --border: #E5E7EB;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 8px 30px rgba(139, 92, 246, 0.15);
    --radius: 12px;
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

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

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

/* ===== Navbar ===== */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: 64px;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 24px;
}

.nav-link {
    color: var(--text);
    font-size: 0.95rem;
    padding: 8px 4px;
    border-bottom: 2px solid transparent;
}
.nav-link:hover, .nav-link.active { color: var(--primary); border-bottom-color: var(--primary); }

.nav-right { display: flex; gap: 12px; align-items: center; }

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 5px;
}
.nav-toggle span {
    width: 24px; height: 2px;
    background: var(--text);
    border-radius: 2px;
    transition: var(--transition);
}

/* ===== Buttons ===== */
.btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: 8px;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    border: 2px solid transparent;
    transition: var(--transition);
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff !important;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4); }

.btn-outline {
    background: transparent;
    border-color: var(--primary);
    color: var(--primary) !important;
}
.btn-outline:hover { background: var(--primary); color: #fff !important; }

.btn-login {
    background: transparent;
    color: var(--primary) !important;
    border: none;
    padding: 8px 16px;
}
.btn-login:hover { color: var(--primary-dark) !important; }

.btn-register {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #fff !important;
    padding: 8px 20px;
    border-radius: 20px;
}
.btn-register:hover { transform: translateY(-2px); box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4); }

.btn-lg { padding: 14px 32px; font-size: 1.05rem; }
.btn-block { width: 100%; }
.btn-sm { padding: 6px 14px; font-size: 0.85rem; }

/* ===== Hero ===== */
.hero {
    padding: 120px 20px 80px;
    text-align: center;
    background: linear-gradient(135deg, #F8F5FF 0%, #EDE9FE 50%, #FCE7F3 100%);
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 16px;
}

.hero-content p {
    font-size: 1.15rem;
    color: var(--text-light);
    margin-bottom: 40px;
}

.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* ===== Sections ===== */
.section { padding: 80px 0; }
.section-title {
    text-align: center;
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 48px;
    position: relative;
}
.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    margin: 12px auto 0;
    border-radius: 2px;
}

/* ===== Categories ===== */
.categories { padding: 80px 0; }
.category-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 24px;
}

.category-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 32px 24px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
    color: var(--text) !important;
}
.category-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-hover); }

.category-icon { font-size: 2.5rem; margin-bottom: 16px; }
.category-card h3 { font-size: 1.2rem; margin-bottom: 8px; }
.category-card p { font-size: 0.9rem; color: var(--text-light); }

/* ===== Article List ===== */
.article-list { display: grid; gap: 20px; }

.article-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}
.article-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-hover); }

.article-card h3 { font-size: 1.15rem; margin-bottom: 8px; }
.article-card h3 a { color: var(--text); }
.article-card h3 a:hover { color: var(--primary); }

.article-meta {
    display: flex;
    gap: 16px;
    font-size: 0.85rem;
    color: var(--text-light);
    margin-top: 12px;
    flex-wrap: wrap;
}
.article-meta span { display: flex; align-items: center; gap: 4px; }

.article-summary {
    color: var(--text-light);
    font-size: 0.9rem;
    line-height: 1.6;
    margin-top: 8px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.load-more { text-align: center; margin-top: 40px; }

/* ===== Level Cards ===== */
.level-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 16px;
}

.level-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 24px 16px;
    text-align: center;
    box-shadow: var(--shadow);
}

.level-badge {
    width: 56px;
    height: 56px;
    line-height: 56px;
    border-radius: 50%;
    margin: 0 auto 12px;
    font-weight: 700;
    font-size: 1rem;
    color: #fff;
}
.lv1 { background: #9CA3AF; }
.lv2 { background: #6B7280; }
.lv3 { background: #3B82F6; }
.lv4 { background: #8B5CF6; }
.lv5 { background: #F59E0B; }
.lv6 { background: #EC4899; }
.lv7 { background: #EF4444; }

.level-card p { font-weight: 600; margin-bottom: 4px; }
.level-card small { color: var(--text-light); font-size: 0.8rem; }

/* ===== Auth Pages ===== */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    background: linear-gradient(135deg, #F8F5FF 0%, #EDE9FE 50%, #FCE7F3 100%);
}

.auth-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 48px 40px;
    width: 100%;
    max-width: 420px;
    box-shadow: 0 4px 25px rgba(0, 0, 0, 0.1);
}

.auth-logo {
    display: block;
    text-align: center;
    font-size: 1.8rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 32px;
}

.auth-card h2 { text-align: center; margin-bottom: 32px; font-size: 1.5rem; }

.form-group { margin-bottom: 20px; }
.form-group label {
    display: block;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text);
}
.form-group input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border);
    border-radius: 8px;
    font-size: 0.95rem;
    transition: var(--transition);
    outline: none;
}
.form-group input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.15); }

.form-error {
    color: #EF4444;
    font-size: 0.85rem;
    margin-bottom: 16px;
    min-height: 20px;
}

.auth-footer { text-align: center; margin-top: 20px; font-size: 0.9rem; color: var(--text-light); }
.auth-footer a { font-weight: 600; }

/* ===== Footer ===== */
.footer {
    background: #fff;
    border-top: 1px solid var(--border);
    padding: 24px 0;
    text-align: center;
    color: var(--text-light);
    font-size: 0.9rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 64px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        flex-direction: column;
        padding: 20px;
        border-bottom: 1px solid var(--border);
    }
    .nav-menu.active { display: flex; }
    .nav-toggle { display: flex; }
    .hero-content h1 { font-size: 2rem; }
    .auth-card { padding: 32px 24px; }
}