:root {
    --primary: #2563eb;
    --text: #1f2937;
    --bg: #f9fafb;
    --sidebar-bg: #ffffff;
    --border: #e5e7eb;
}

body {
    margin: 0;
    font-family: 'Inter', sans-serif;
    background-color: var(--bg);
    color: var(--text);
}

/* Header */
.main-header {
    height: 70px;
    background: #fff;
    display: flex;
    align-items: center;
    padding: 0 2rem;
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo { height: 40px; }

.top-nav {
    margin-left: 3rem;
    display: flex;
    gap: 1.5rem;
}

.top-nav a {
    text-decoration: none;
    color: var(--text);
    font-weight: 500;
    transition: color 0.2s;
}

.top-nav a:hover { color: var(--primary); }

.user-menu { margin-left: auto; display: flex; gap: 1rem; align-items: center; }

/* Layout */
.main-layout {
    display: flex;
   width: 100%;
    margin: 0 auto;
}

/* Sidebar */
.sidebar {
    width: 260px;
    background: var(--sidebar-bg);
    padding: 2rem;
    height: calc(100vh - 70px);
    border-right: 1px solid var(--border);
    position: sticky;
    top: 70px;
}

.sidebar-group h3 {
    font-size: 0.8rem;
    text-transform: uppercase;
    color: #9ca3af;
    letter-spacing: 0.05rem;
    margin-bottom: 1rem;
}

.sidebar-group ul { list-style: none; padding: 0; margin-bottom: 2rem; }

.sidebar-group ul li a {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 0;
    text-decoration: none;
    color: var(--text);
    transition: 0.2s;
}

.sidebar-group ul li a:hover { color: var(--primary); padding-left: 5px; }

/* Content */
.content {
    flex: 1;
    padding: 2rem;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.course-card {
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--border);
    transition: transform 0.2s, box-shadow 0.2s;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1);
}

.course-img { height: 160px; width: 100%; }

.course-info { padding: 1.5rem; }

.badge {
    background: #dbeafe;
    color: var(--primary);
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: bold;
}

.course-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 1rem;
}

.price { font-size: 1.2rem; font-weight: bold; color: var(--primary); }

.btn-buy {
    background: var(--primary);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
}

.user-menu a, .btn-logout {
    text-decoration: none;
    font-size: 14px;
    padding: 8px 16px;
    border-radius: 6px;
    transition: 0.3s;
    border: 1px solid #e5e7eb;
}

.btn-login {
    color: #374151;
    background: transparent;
}

.btn-login:hover {
    background: #f3f4f6;
}

.btn-register, .btn-dashboard {
    background: #2563eb;
    color: white !important;
    border-color: #2563eb !important;
}

.btn-register:hover {
    background: #1d4ed8;
}

.btn-logout {
    background: #fff;
    color: #ef4444;
    cursor: pointer;
    border-color: #fecaca;
    margin-left: 10px;
}