html { font-size: 15px; }
body { 
    font-family: 'Inter', 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif; 
    background: #f9fafb; 
    color: #111827; 
    -webkit-font-smoothing: antialiased;
    line-height: 1.6;
}

/* Professional Navbar */
.navbar {
    background: #ffffff !important;
    border-bottom: 1px solid #e5e7eb;
    transition: all 0.2s ease;
    padding-top: 1rem !important;
    padding-bottom: 1rem !important;
}
.navbar-brand { font-weight: 700; color: #111827 !important; letter-spacing: -0.5px; }
.nav-link { font-weight: 500; color: #4b5563; transition: color 0.2s ease; font-size: 0.95rem; }
.nav-link:hover { color: var(--bs-primary); }
.nav-vip-badge { background: #fffbeb; color: #d97706 !important; border-radius: 6px; padding: 4px 10px; border: 1px solid #fde68a; }
[data-bs-theme="dark"] .nav-vip-badge { background: rgba(245,158,11,0.1); border-color: rgba(245,158,11,0.2); }

/* Solid Premium Buttons */
.btn { font-weight: 600; letter-spacing: 0.2px; transition: all 0.2s; border-radius: 8px; padding: 10px 20px; }
.btn-primary { 
    background: var(--bs-primary);
    border: 1px solid var(--bs-primary);
    color: var(--bs-primary-color-text);
    box-shadow: 0 1px 2px rgba(0,0,0,0.05);
}
.btn-primary:hover, .btn-primary:focus {
    background: #111827;
    border-color: #111827;
    color: #ffffff;
    transform: translateY(-1px);
    box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -1px rgba(0,0,0,0.06);
}
.btn-outline-primary {
    border: 1px solid #d1d5db;
    color: #374151;
    background: #ffffff;
}
.btn-outline-primary:hover {
    background: #f3f4f6;
    color: #111827;
    border-color: #9ca3af;
}

/* Clean Forms */
.form-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: #374151;
    margin-bottom: 0.5rem;
}
.form-control, .form-select {
    border-radius: 8px;
    padding: 0.75rem 1rem;
    border: 1px solid #d1d5db;
    background-color: #ffffff;
    font-size: 0.95rem;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
    transition: border-color 0.15s ease-in-out, box-shadow 0.15s ease-in-out;
}
.form-control:focus, .form-select:focus {
    border-color: var(--bs-primary);
    box-shadow: 0 0 0 3px rgba(var(--bs-primary-rgb), 0.2);
    outline: 0;
}
.mb-3 { margin-bottom: 1.5rem !important; }

/* Professional Course Cards */
.course-card {
    background: #ffffff;
    border: 1px solid #e5e7eb;
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.2s ease;
    box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    display: flex;
    flex-direction: column;
}
.course-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
}
.course-img-wrap {
    position: relative; padding-top: 56.25%; background: #f3f4f6;
    overflow: hidden;
    border-bottom: 1px solid #e5e7eb;
}
.course-img-wrap img {
    position: absolute; top: 0; left: 0; width: 100%; height: 100%; object-fit: cover;
    transition: transform 0.3s ease;
}
.badge-level { 
    position: absolute; top: 12px; left: 12px; z-index: 2; 
    background: #111827 !important;
    color: #ffffff;
    font-weight: 700; padding: 6px 12px; border-radius: 6px;
    font-size: 0.75rem; letter-spacing: 0.5px; text-transform: uppercase;
}
.course-price { font-size: 1.15rem; font-weight: 700; color: #111827; }
.filter-btn { border-radius: 6px; padding: 8px 16px; font-weight: 500; font-size: 0.9rem; transition: all 0.2s; border: 1px solid transparent; }
.filter-btn.btn-primary { box-shadow: none; background: #111827; border-color: #111827; color: white; }
.filter-btn.btn-primary:hover { background: #374151; border-color: #374151; }
.filter-btn.btn-light { background: #f3f4f6; color: #4b5563; border: 1px solid #e5e7eb; }
.filter-btn.btn-light:hover { background: #e5e7eb; color: #111827; }

/* Auth Cards */
.auth-card {
    border-radius: 16px;
    border: 1px solid #e5e7eb;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    background: #ffffff;
}

/* Typography refinements */
h1, h2, h3, h4, h5, h6 { font-weight: 700; color: #111827; letter-spacing: -0.025em; }
.text-muted { color: #6b7280 !important; }