:root {
    --primary-blue: #3b82f6;
    --primary-blue-hover: #2563eb;
    --bg-color: #0f172a; /* Fallback for 3D bg */
    --surface-color: rgba(255, 255, 255, 0.05); /* Glassmorphism */
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --border-color: rgba(255, 255, 255, 0.1);
    
    --blue-light: rgba(59, 130, 246, 0.2);
    --purple-light: rgba(168, 85, 247, 0.2);
    --green-light: rgba(34, 197, 94, 0.2);
    
    --text-blue: #60a5fa;
    --text-purple: #c084fc;
    --text-green: #4ade80;
    --text-yellow: #fbbf24;
    
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
    
    --radius-md: 0.75rem;
    --radius-lg: 1.25rem;
    --radius-xl: 1.5rem;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.5;
    overflow-x: hidden;
}

/* 3D Background Container */
#vanta-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
}

/* Typography & Utilities */
.text-gray { color: var(--text-muted); }
.text-blue { color: var(--text-blue); }
.text-purple { color: var(--text-purple); }
.text-green { color: var(--text-green); }
.text-yellow { color: var(--text-yellow); }

.bg-blue-light { background-color: var(--blue-light); }
.bg-purple-light { background-color: var(--purple-light); }
.bg-green-light { background-color: var(--green-light); }

.text-center { text-align: center; }
.mt-2 { margin-top: 0.5rem; }
.mt-4 { margin-top: 1rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 0.75rem; }
.mb-4 { margin-bottom: 1rem; }
.py-4 { padding-top: 1rem; padding-bottom: 1rem; }
.w-100 { width: 100%; }
.text-sm { font-size: 0.875rem; }

/* Views */
.view {
    display: none;
    min-height: 100vh;
}
.view.active {
    display: block;
}

/* Auth View */
.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 1rem;
}

.auth-card {
    background: var(--surface-color);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border-color);
    padding: 2.5rem;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 400px;
    text-align: center;
    transform-style: preserve-3d;
}

.logo {
    font-size: 1.8rem;
    font-weight: 800;
    background: linear-gradient(to right, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transform: translateZ(30px);
}

.auth-card h2 { margin-bottom: 0.25rem; font-weight: 600; transform: translateZ(20px); }
.auth-card .subtitle { color: var(--text-muted); margin-bottom: 2rem; transform: translateZ(20px); }

.divider {
    display: flex;
    align-items: center;
    text-align: center;
    margin: 1.5rem 0;
    color: var(--text-muted);
    font-size: 0.875rem;
    transform: translateZ(15px);
}
.divider::before, .divider::after {
    content: '';
    flex: 1;
    border-bottom: 1px solid var(--border-color);
}
.divider span { padding: 0 10px; }

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.25rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    transform: translateZ(25px);
    position: relative;
    overflow: hidden;
}
.btn::after {
    content: ''; position: absolute; top: 0; left: -100%; width: 100%; height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: all 0.5s ease;
}
.btn:hover::after { left: 100%; }

.btn-primary {
    background: linear-gradient(135deg, var(--primary-blue), #8b5cf6);
    color: white;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
}
.btn-primary:hover {
    transform: translateZ(35px) translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.6);
}
.btn-outline {
    background-color: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    color: var(--text-main);
    backdrop-filter: blur(5px);
}
.btn-outline:hover {
    background-color: rgba(255, 255, 255, 0.1);
    transform: translateZ(30px) translateY(-2px);
}
.btn-sm { padding: 0.4rem 0.8rem; font-size: 0.875rem; }

/* Navbar */
.navbar {
    background: rgba(15, 23, 42, 0.7);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    padding: 1rem 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-brand {
    font-weight: 800;
    font-size: 1.5rem;
    background: linear-gradient(to right, #60a5fa, #c084fc);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.nav-brand i { color: #60a5fa; }

.nav-links {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    font-size: 0.95rem;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 0;
    position: relative;
    transition: color 0.3s, transform 0.2s;
}

.nav-link:hover, .nav-link.active {
    color: var(--text-main);
    transform: translateY(-2px);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -1rem;
    left: 0;
    width: 100%;
    height: 3px;
    background: linear-gradient(90deg, #60a5fa, #c084fc);
    border-radius: 3px 3px 0 0;
    box-shadow: 0 -2px 10px rgba(96, 165, 250, 0.5);
}

.nav-user {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.badge {
    padding: 0.25rem 0.75rem;
    border-radius: 999px;
    font-size: 0.75rem;
    font-weight: 600;
    backdrop-filter: blur(5px);
}
.badge-student { background-color: var(--blue-light); color: var(--text-blue); border: 1px solid rgba(59, 130, 246, 0.3); }
.badge-open { background-color: rgba(255,255,255,0.05); color: var(--text-muted); border: 1px solid var(--border-color); }

/* Main Content */
.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 5%;
}

.page-section {
    display: none;
}
.page-section.active {
    display: block;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2.5rem;
}
.section-header h2 { font-weight: 700; font-size: 2rem; letter-spacing: -0.5px; }

.search-bar {
    position: relative;
    width: 300px;
}
.search-bar input {
    width: 100%;
    padding: 0.75rem 1rem 0.75rem 2.5rem;
    background: rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    color: white;
    border-radius: var(--radius-md);
    outline: none;
    transition: all 0.3s;
    backdrop-filter: blur(5px);
}
.search-bar input:focus { 
    border-color: var(--text-blue); 
    box-shadow: 0 0 15px rgba(96, 165, 250, 0.3);
}
.search-bar i {
    position: absolute;
    left: 1rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

/* Grid Layouts */
.grid-layout {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
}

/* Cards (Glassmorphism & 3D) */
.card {
    background: var(--surface-color);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    transition: border-color 0.3s;
    transform-style: preserve-3d; /* For child 3D elements */
    box-shadow: var(--shadow-sm);
}

.item-card {
    display: flex;
    flex-direction: column;
    height: 100%;
}
.item-badge {
    align-self: flex-start;
    padding: 0.2rem 0.6rem;
    border-radius: 0.25rem;
    font-size: 0.75rem;
    background: rgba(255,255,255,0.05);
    color: var(--text-muted);
    margin-bottom: 0.75rem;
    border: 1px solid var(--border-color);
    transform: translateZ(20px);
}
.item-title { font-weight: 600; margin-bottom: 0.5rem; font-size: 1.1rem; transform: translateZ(30px); }
.item-price { font-size: 1.5rem; font-weight: 800; color: var(--text-blue); margin-bottom: 1rem; transform: translateZ(40px); }
.item-seller { display: flex; align-items: center; gap: 0.5rem; font-size: 0.875rem; color: var(--text-muted); margin-bottom: 1.5rem; flex: 1; transform: translateZ(20px); }
.item-seller i.fa-star { color: var(--text-yellow); }

.mentor-card {
    text-align: center;
}
.mentor-avatar {
    width: 90px;
    height: 90px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary-blue), #8b5cf6);
    color: white;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 10px 20px rgba(0,0,0,0.3);
    border: 3px solid rgba(255,255,255,0.1);
    transform: translateZ(40px);
}
.mentor-name { font-weight: 600; font-size: 1.25rem; transform: translateZ(30px); }
.mentor-skill { color: var(--text-muted); font-size: 0.95rem; margin-bottom: 0.5rem; transform: translateZ(20px); }
.mentor-level { 
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 99px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 1rem;
    transform: translateZ(25px);
    border: 1px solid rgba(255,255,255,0.1);
}
.level-top { background: var(--purple-light); color: var(--text-purple); }
.level-new { background: var(--green-light); color: var(--text-green); }

/* Dashboard Specific */
.header-banner {
    background: linear-gradient(135deg, rgba(59, 130, 246, 0.4), rgba(139, 92, 246, 0.4));
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255,255,255,0.2);
    color: white;
    padding: 3rem;
    border-radius: var(--radius-xl);
    margin-bottom: 3rem;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}
.header-banner::before {
    content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 60%);
    animation: rotate 20s linear infinite;
}
@keyframes rotate { 100% { transform: rotate(360deg); } }

.header-banner h1 { margin-bottom: 0.5rem; font-size: 2.5rem; position: relative; z-index: 1; }
.header-banner p { font-size: 1.1rem; color: rgba(255,255,255,0.8); position: relative; z-index: 1; }

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.dash-card {
    background: var(--surface-color);
    backdrop-filter: blur(12px);
    padding: 2rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: all 0.3s;
    transform-style: preserve-3d;
}
.dash-card:hover {
    border-color: rgba(96, 165, 250, 0.5);
    box-shadow: 0 15px 30px rgba(0,0,0,0.4), 0 0 20px rgba(96, 165, 250, 0.2);
}
.dash-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    transform: translateZ(30px);
    box-shadow: inset 0 0 10px rgba(255,255,255,0.1);
}
.dash-card h3 { transform: translateZ(20px); font-size: 1.25rem; margin-bottom: 0.5rem; }
.dash-card p { transform: translateZ(15px); color: var(--text-muted); }

/* Forms */
.form-group { margin-bottom: 1.5rem; }
.form-group label { display: block; margin-bottom: 0.5rem; font-weight: 500; font-size: 0.95rem; color: var(--text-muted); }
.form-control {
    width: 100%;
    padding: 0.85rem 1rem;
    background: rgba(0,0,0,0.2);
    border: 1px solid var(--border-color);
    color: white;
    border-radius: var(--radius-md);
    outline: none;
    transition: all 0.3s;
    backdrop-filter: blur(5px);
}
.form-control:focus { border-color: var(--text-blue); box-shadow: 0 0 10px rgba(59,130,246,0.2); }

.teach-container { max-width: 600px; margin: 0 auto; }

/* Profile */
.profile-layout { max-width: 800px; margin: 0 auto; }
.profile-card { padding: 3rem 2rem; }
.badges-container { display: flex; gap: 0.5rem; justify-content: center; flex-wrap: wrap; }
.profile-stats {
    display: flex;
    justify-content: space-around;
    border-top: 1px solid rgba(255,255,255,0.05);
    padding-top: 2rem;
    margin-top: 2rem;
}
.stat-box { text-align: center; }
.stat-box h3 { font-size: 0.9rem; color: var(--text-muted); font-weight: 500; margin-bottom: 0.5rem; }
.stat-box .score { font-size: 2.5rem; font-weight: 800; background: linear-gradient(to right, #60a5fa, #c084fc); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }

/* Modals */
.modal {
    display: none;
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(0, 0, 0, 0.6);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(8px);
}
.modal.active { display: flex; }
.modal-content {
    width: 100%; max-width: 400px;
    margin: 1rem;
    background: rgba(15, 23, 42, 0.9);
    border: 1px solid rgba(255,255,255,0.1);
}
.modal-header {
    display: flex; justify-content: space-between; align-items: center;
    margin-bottom: 1.5rem;
}
.btn-close {
    background: transparent; border: none; font-size: 1.5rem; color: var(--text-muted);
    cursor: pointer; transition: color 0.3s;
}
.btn-close:hover { color: white; }
.qr-placeholder {
    width: 180px; height: 180px; margin: 0 auto;
    background: rgba(255,255,255,0.05); border-radius: var(--radius-md);
    display: flex; align-items: center; justify-content: center;
    border: 2px dashed rgba(255,255,255,0.2);
}

/* Utilities */
.student-only { display: none; }

/* Responsive */
@media (max-width: 768px) {
    .navbar { flex-direction: column; gap: 1rem; padding: 1rem; }
    .nav-links { overflow-x: auto; width: 100%; padding-bottom: 0.5rem; justify-content: center; }
    .nav-link { white-space: nowrap; }
    .dashboard-grid { grid-template-columns: 1fr; }
    .search-bar { width: 100%; margin-top: 1rem; }
    .section-header { flex-direction: column; align-items: flex-start; }
}