:root {
    --primary: #0095f6;
    --primary-hover: #1877f2;
    --bg-primary: #000000;
    --bg-secondary: #121212;
    --bg-elevated: #1c1c1e;
    --bg-card: #1c1c1e;
    --border-color: #262626;
    --border-light: #363636;
    --text-primary: #f5f5f5;
    --text-secondary: #a8a8a8;
    --text-muted: #737373;
    --text-link: #e0f1ff;
    --danger: #ed4956;
    --success: #58c322;
    --warning: #fdcb5c;
    --separator: #262626;
    --overlay: rgba(0,0,0,.65);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

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

.container { max-width: 935px; margin: 0 auto; padding: 0 1rem; }

/* ── Buttons (shadcn-inspired, flat, no gradients) ── */
.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: .5rem;
    padding: .5rem 1rem; border-radius: var(--radius-sm); font-weight: 600;
    font-size: .875rem; text-decoration: none; cursor: pointer; border: none;
    transition: background .15s, opacity .15s; font-family: inherit; line-height: 1.4;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: var(--bg-elevated); color: var(--text-primary); border: 1px solid var(--border-color); }
.btn-secondary:hover { background: var(--border-color); }
.btn-danger { background: transparent; color: var(--danger); border: 1px solid var(--border-color); }
.btn-danger:hover { background: rgba(237,73,86,.1); }
.btn-ghost { background: transparent; color: var(--text-secondary); }
.btn-ghost:hover { color: var(--text-primary); }
.btn-sm { padding: .375rem .75rem; font-size: .8125rem; }
.btn-premium { background: var(--primary); color: #fff; }
.btn-premium:hover { background: var(--primary-hover); }
.btn-glass { background: var(--bg-elevated); border: 1px solid var(--border-color); color: var(--text-primary); }
.btn-glass:hover { background: var(--border-color); }
.btn-success { background: var(--success); color: #fff; }

/* ── Forms ── */
.form-group { margin-bottom: 1rem; }
.form-label { display: block; font-size: .75rem; font-weight: 600; color: var(--text-secondary); margin-bottom: .375rem; text-transform: uppercase; letter-spacing: .04em; }
.input-premium, .form-input {
    width: 100%; padding: .625rem .75rem; background: var(--bg-primary);
    border: 1px solid var(--border-color); border-radius: var(--radius-sm);
    color: var(--text-primary); font-size: .875rem; font-family: inherit;
    transition: border-color .15s;
}
.input-premium:focus, .form-input:focus { outline: none; border-color: var(--border-light); }

/* ── Navbar ── */
.navbar { padding: 0; border-bottom: 1px solid var(--separator); background: var(--bg-primary); position: sticky; top: 0; z-index: 500; }
.nav-content { display: flex; justify-content: space-between; align-items: center; height: 60px; }
.nav-logo { font-size: 1.25rem; font-weight: 700; text-decoration: none; color: var(--text-primary); letter-spacing: -.02em; }
.nav-links { display: flex; align-items: center; gap: 1.25rem; }
.nav-link { color: var(--text-secondary); text-decoration: none; font-size: .875rem; font-weight: 500; transition: color .15s; }
.nav-link:hover { color: var(--text-primary); }
.user-nav { display: flex; align-items: center; gap: .75rem; padding-left: .75rem; border-left: 1px solid var(--separator); }
.user-profile-link { display: flex; align-items: center; gap: .5rem; }
.logout-form { display: inline; }
.logout-btn { background: none; border: none; cursor: pointer; font-size: .8125rem; color: var(--text-muted); font-family: inherit; transition: color .15s; }
.logout-btn:hover { color: var(--danger); }

/* ── Avatar ── */
.avatar { width: 2rem; height: 2rem; border-radius: 50%; border: 1px solid var(--border-color); object-fit: cover; }
.avatar-lg { width: 5rem; height: 5rem; border-radius: 50%; object-fit: cover; border: 2px solid var(--border-color); }

/* ── Cards (glass → shadcn flat dark) ── */
.glass {
    background: var(--bg-card); border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
}

/* ── Utilities ── */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.flex-1 { flex: 1; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: .5rem; }
.gap-4 { gap: 1rem; }
.gap-8 { gap: 2rem; }
.mt-2 { margin-top: .5rem; }
.mt-4 { margin-top: 1rem; }
.mb-2 { margin-bottom: .5rem; }
.mb-4 { margin-bottom: 1rem; }
.p-4 { padding: 1rem; }
.p-6 { padding: 1.5rem; }
.p-8 { padding: 2rem; }
.p-10 { padding: 2.5rem; }
.w-full { width: 100%; }
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--text-secondary); }
.text-gradient { color: var(--text-primary); font-weight: 700; }
.font-bold { font-weight: 700; }
.font-medium { font-weight: 500; }
.uppercase { text-transform: uppercase; }
.tracking-wider { letter-spacing: .04em; }
.tracking-widest { letter-spacing: .08em; }
.hidden { display: none; }
.grid { display: grid; gap: 1rem; }
@media (min-width: 768px) {
    .grid-2 { grid-template-columns: repeat(2, 1fr); }
    .grid-3 { grid-template-columns: repeat(3, 1fr); }
}

h1 { font-size: 1.75rem; font-weight: 700; letter-spacing: -.02em; }
h2 { font-size: 1.375rem; font-weight: 700; }
h3 { font-size: 1.125rem; font-weight: 600; }

/* ── Table ── */
.table-container { width: 100%; overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
th { background: var(--bg-elevated); padding: .75rem 1rem; text-align: left; font-weight: 600; font-size: .75rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: .04em; border-bottom: 1px solid var(--border-color); }
td { padding: .75rem 1rem; border-bottom: 1px solid var(--border-color); font-size: .875rem; }
tr:hover { background: rgba(255,255,255,.02); }

/* ── Badges ── */
.badge { padding: .25rem .625rem; border-radius: 999px; font-size: .6875rem; font-weight: 600; text-transform: uppercase; letter-spacing: .04em; }
.badge-student { background: rgba(88,195,34,.15); color: var(--success); }
.badge-teacher { background: rgba(0,149,246,.15); color: var(--primary); }
.badge-admin { background: rgba(168,85,247,.15); color: #c084fc; }

/* ── Alerts ── */
.alert { padding: .75rem 1rem; border-radius: var(--radius-sm); margin-bottom: 1rem; font-size: .875rem; }
.alert-success { background: rgba(88,195,34,.1); border: 1px solid rgba(88,195,34,.2); color: var(--success); }
.error-text { color: var(--danger); font-size: .8125rem; margin-top: .25rem; }

/* ── Spinner ── */
.spinner { width: 28px; height: 28px; border: 3px solid var(--border-color); border-top-color: var(--text-secondary); border-radius: 50%; animation: spin .6s linear infinite; margin: 2rem auto; }
@keyframes spin { to { transform: rotate(360deg); } }

@media (max-width: 640px) {
    .hidden-mobile { display: none; }
    .navbar { position: static; }
    .nav-content { height: 52px; }
}