/* ===== CSS Variables ===== */
:root {
    --primary-color: #1a5276;
    --primary-dark: #154360;
    --primary-light: #2980b9;
    --secondary-color: #d4a017;
    --secondary-light: #f1c40f;
    --success-color: #27ae60;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --text-color: #2c3e50;
    --text-light: #7f8c8d;
    --bg-color: #f8f9fa;
    --white: #ffffff;
    --border-color: #dee2e6;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 5px 25px rgba(0, 0, 0, 0.15);
    --radius: 8px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

/* ===== Header ===== */
.header {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow);
}

.header-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 20px;
    max-width: 1400px;
    margin: 0 auto;
}

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

.logo-icon {
    width: 45px;
    height: 45px;
    background: var(--secondary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
}

.logo-text {
    font-size: 24px;
    font-weight: bold;
    letter-spacing: 0.5px;
}

.logo-text span {
    color: var(--secondary-color);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 15px;
}

.search-box {
    position: relative;
}

.search-box input {
    padding: 10px 40px 10px 15px;
    border: none;
    border-radius: 25px;
    width: 300px;
    font-size: 14px;
    background: rgba(255, 255, 255, 0.2);
    color: var(--white);
}

.search-box input::placeholder {
    color: rgba(255, 255, 255, 0.7);
}

.search-box button {
    position: absolute;
    right: 5px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    color: var(--white);
    cursor: pointer;
    padding: 8px;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background: var(--secondary-light);
    transform: translateY(-2px);
}

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

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

/* ===== Announcement Bar ===== */
.announcement-bar {
    background: var(--secondary-color);
    padding: 8px 20px;
    text-align: center;
    font-size: 14px;
    color: var(--white);
}

.announcement-bar a {
    color: var(--white);
    font-weight: 600;
    text-decoration: underline;
}

/* ===== Main Layout ===== */
.main-container {
    display: flex;
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
    gap: 20px;
}

/* ===== Sidebar ===== */
.sidebar {
    width: 280px;
    flex-shrink: 0;
}

.sidebar-menu {
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.sidebar-title {
    background: var(--primary-color);
    color: var(--white);
    padding: 15px 20px;
    font-size: 16px;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 10px;
}

.menu-item {
    position: relative;
}

.menu-link {
    display: flex;
    align-items: center;
    padding: 12px 20px;
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition);
    font-size: 14px;
}

.menu-link:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}

.menu-link.active {
    background: #fff3cd;
    color: var(--secondary-color);
    font-weight: 600;
}

.menu-link i {
    width: 20px;
    margin-right: 10px;
    color: var(--text-light);
}

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

.menu-arrow {
    margin-left: auto;
    font-size: 12px;
    transition: var(--transition);
}

/* ===== Mega Menu ===== */
.mega-menu {
    position: absolute;
    left: 100%;
    top: 0;
    background: var(--white);
    width: 700px;
    padding: 25px;
    box-shadow: var(--shadow-lg);
    border-radius: 0 var(--radius) var(--radius) 0;
    display: none;
    z-index: 100;
}

.menu-item:hover .mega-menu {
    display: block;
}

.mega-menu-header {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 15px;
}

.mega-tab {
    padding: 10px 25px;
    border: none;
    background: var(--bg-color);
    color: var(--text-color);
    font-weight: 600;
    cursor: pointer;
    border-radius: var(--radius);
    transition: var(--transition);
}

.mega-tab.active {
    background: var(--secondary-color);
    color: var(--white);
}

.mega-content {
    display: none;
}

.mega-content.active {
    display: block;
}

.mega-section {
    margin-bottom: 20px;
}

.mega-section-title {
    color: var(--primary-color);
    font-size: 15px;
    font-weight: 700;
    margin-bottom: 12px;
    padding-bottom: 8px;
    border-bottom: 2px solid var(--primary-light);
}

.mega-items {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 10px;
}

.mega-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    border-radius: var(--radius);
    transition: var(--transition);
    font-size: 14px;
}

.mega-item:hover {
    background: var(--bg-color);
    color: var(--primary-color);
}

.mega-item i {
    color: var(--text-light);
    font-size: 12px;
}

/* ===== Sidebar Ad ===== */
.sidebar-ad {
    margin-top: 20px;
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.sidebar-ad img {
    width: 100%;
    display: block;
}

/* ===== Content Area ===== */
.content {
    flex: 1;
    min-width: 0;
}

/* ===== Tab Navigation ===== */
.content-tabs {
    display: flex;
    gap: 5px;
    margin-bottom: 20px;
}

.content-tab {
    padding: 12px 30px;
    background: var(--white);
    border: none;
    border-radius: var(--radius) var(--radius) 0 0;
    cursor: pointer;
    font-size: 15px;
    font-weight: 600;
    color: var(--text-light);
    transition: var(--transition);
}

.content-tab.active {
    background: var(--secondary-color);
    color: var(--white);
}

.content-tab:hover:not(.active) {
    background: var(--bg-color);
    color: var(--primary-color);
}

/* ===== Course Grid ===== */
.tab-content {
    display: none;
    background: var(--white);
    padding: 25px;
    border-radius: 0 var(--radius) var(--radius) var(--radius);
    box-shadow: var(--shadow);
}

.tab-content.active {
    display: block;
}

.section-title {
    color: var(--primary-color);
    font-size: 18px;
    font-weight: 700;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 3px solid var(--primary-light);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 30px;
}

.course-card {
    background: var(--white);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transition: var(--transition);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.course-thumbnail {
    position: relative;
    height: 130px;
    overflow: hidden;
}

.course-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.course-badge {
    position: absolute;
    top: 10px;
    left: 10px;
    background: var(--danger-color);
    color: var(--white);
    padding: 4px 10px;
    font-size: 11px;
    font-weight: 600;
    border-radius: 4px;
}

.course-info {
    padding: 15px;
}

.course-title {
    font-size: 14px;
    font-weight: 600;
    color: var(--text-color);
    margin-bottom: 8px;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-meta {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 12px;
    color: var(--text-light);
    margin-bottom: 10px;
}

.course-price {
    display: flex;
    align-items: center;
    gap: 10px;
}

.price-sale {
    color: var(--danger-color);
    font-weight: 700;
    font-size: 16px;
}

.price-original {
    color: var(--text-light);
    text-decoration: line-through;
    font-size: 13px;
}

/* ===== Footer ===== */
.footer {
    background: var(--primary-dark);
    color: var(--white);
    padding: 40px 20px 20px;
    margin-top: 40px;
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.footer-section h3 {
    margin-bottom: 20px;
    font-size: 18px;
}

.footer-section ul li {
    margin-bottom: 10px;
}

.footer-section a:hover {
    color: var(--secondary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
    margin-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    font-size: 14px;
}

/* ===== User Dropdown ===== */
.user-menu {
    position: relative;
}

.user-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    border: 2px solid var(--secondary-color);
}

.user-dropdown {
    position: absolute;
    right: 0;
    top: 100%;
    background: var(--white);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    min-width: 200px;
    display: none;
    z-index: 100;
}

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

.user-dropdown a {
    display: block;
    padding: 12px 20px;
    color: var(--text-color);
    transition: var(--transition);
}

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

/* ===== Login Modal ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--white);
    padding: 40px;
    border-radius: var(--radius);
    max-width: 400px;
    width: 90%;
    text-align: center;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
}

.modal-content.modal-lg {
    max-width: 800px;
}

.modal-title {
    font-size: 24px;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.google-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    width: 100%;
    padding: 15px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    background: var(--white);
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: var(--transition);
}

.google-btn:hover {
    border-color: var(--primary-color);
    background: var(--bg-color);
}

.google-btn img {
    width: 24px;
    height: 24px;
}

.modal-close {
    position: absolute;
    top: 15px;
    right: 20px;
    font-size: 28px;
    cursor: pointer;
    color: var(--text-light);
}

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

.modal-content {
    position: relative;
}

/* Auth Form Styles */
.form-group {
    margin-bottom: 15px;
}

.form-group input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-size: 14px;
    transition: var(--transition);
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(26, 82, 118, 0.1);
}

.auth-message {
    padding: 10px 15px;
    border-radius: var(--radius);
    margin-bottom: 15px;
    font-size: 14px;
    display: none;
}

.auth-message.error {
    background: #fce4ec;
    color: var(--danger-color);
    display: block;
}

.auth-message.success {
    background: #e8f5e9;
    color: var(--success-color);
    display: block;
}

.auth-links {
    margin-top: 20px;
    font-size: 14px;
    color: var(--text-light);
}

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

.auth-links a:hover {
    text-decoration: underline;
}

.auth-links span {
    margin: 0 10px;
}

/* ===== Responsive ===== */
@media (max-width: 1024px) {
    .main-container {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
    }

    .mega-menu {
        position: static;
        width: 100%;
        box-shadow: none;
        border-radius: 0;
    }

    .mega-items {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .header-top {
        flex-direction: column;
        gap: 15px;
    }

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

    .content-tabs {
        overflow-x: auto;
    }

    .course-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .mega-items {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .course-grid {
        grid-template-columns: 1fr;
    }
}