:root {
  --ps-primary: #22c55e;
  --ps-primary-dark: #16a34a;
  --ps-primary-light: #4ade80;
  --ps-bg: #0a0a0a;
  --ps-bg-elevated: #111827;
  --ps-bg-card: rgba(255,255,255,0.05);
  --ps-bg-input: rgba(0,0,0,0.3);
  --ps-bg-sidebar: rgba(0,0,0,0.4);
  --ps-bg-topbar: rgba(0,0,0,0.3);
  --ps-bg-table-head: rgba(0,0,0,0.3);
  --ps-body-gradient: linear-gradient(180deg, #000 0%, var(--ps-bg-elevated) 50%, #000 100%);
  --ps-auth-gradient: radial-gradient(ellipse at top, rgba(34,197,94,0.08) 0%, transparent 60%),
              linear-gradient(180deg, #000, var(--ps-bg-elevated), #000);
  --ps-border: rgba(255,255,255,0.10);
  --ps-text: #ededed;
  --ps-text-muted: #9ca3af;
  --ps-danger: #ef4444;
  --ps-warning: #eab308;
  --ps-success: #22c55e;
  --sidebar-width: 260px;
  --header-height: 64px;
  --radius: 12px;
  --shadow: 0 8px 32px rgba(0,0,0,0.4);
  --ps-badge-muted-bg: rgba(255,255,255,0.08);
  --ps-card-thumb-end: rgba(17,24,39,0.8);
  --ps-alert-info-color: #93c5fd;
}

[data-theme="light"] {
  --ps-bg: #f8fafc;
  --ps-bg-elevated: #ffffff;
  --ps-bg-card: #ffffff;
  --ps-bg-input: #f1f5f9;
  --ps-bg-sidebar: #ffffff;
  --ps-bg-topbar: rgba(255,255,255,0.95);
  --ps-bg-table-head: #f1f5f9;
  --ps-body-gradient: linear-gradient(180deg, #f8fafc 0%, #ffffff 50%, #f1f5f9 100%);
  --ps-auth-gradient: radial-gradient(ellipse at top, rgba(34,197,94,0.12) 0%, transparent 60%),
              linear-gradient(180deg, #f8fafc, #ffffff, #f1f5f9);
  --ps-border: rgba(15,23,42,0.12);
  --ps-text: #0f172a;
  --ps-text-muted: #64748b;
  --ps-shadow: 0 8px 32px rgba(15,23,42,0.08);
  --shadow: var(--ps-shadow);
  --ps-badge-muted-bg: rgba(15,23,42,0.08);
  --ps-card-thumb-end: rgba(241,245,249,0.9);
  --ps-alert-info-color: #2563eb;
}

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

html { scroll-behavior: smooth; }
html[data-theme="dark"] { color-scheme: dark; }
html[data-theme="light"] { color-scheme: light; }

body {
  font-family: 'Outfit', system-ui, -apple-system, sans-serif;
  background: var(--ps-body-gradient);
  color: var(--ps-text);
  min-height: 100vh;
  line-height: 1.6;
}

a { color: var(--ps-primary-light); text-decoration: none; transition: color .2s; }
a:hover { color: var(--ps-primary); }

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

/* Auth layout */
.auth-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  background: var(--ps-auth-gradient);
  position: relative;
}

.auth-card {
  width: 100%;
  max-width: 420px;
  background: var(--ps-bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--ps-border);
  border-radius: var(--radius);
  padding: 2.5rem;
  box-shadow: var(--shadow);
}

.auth-logo {
  text-align: center;
  margin-bottom: 2rem;
}

.auth-logo h1 {
  font-size: 1.5rem;
  font-weight: 700;
  background: linear-gradient(90deg, var(--ps-primary), var(--ps-primary-dark));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.auth-logo p { color: var(--ps-text-muted); font-size: .875rem; margin-top: .25rem; }

/* App layout */
.app-layout { display: flex; min-height: 100vh; }

.sidebar {
  width: var(--sidebar-width);
  background: var(--ps-bg-sidebar);
  backdrop-filter: blur(12px);
  border-right: 1px solid var(--ps-border);
  position: fixed;
  top: 0; left: 0; bottom: 0;
  z-index: 100;
  display: flex;
  flex-direction: column;
  transition: transform .3s ease;
}

.sidebar-brand {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--ps-border);
}

.sidebar-brand h2 {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--ps-primary);
}

.sidebar-brand span { font-size: .75rem; color: var(--ps-text-muted); text-transform: uppercase; letter-spacing: .05em; }

.sidebar-nav { flex: 1; padding: 1rem 0; overflow-y: auto; }

.sidebar-nav a {
  display: flex;
  align-items: center;
  gap: .75rem;
  padding: .75rem 1.5rem;
  color: var(--ps-text-muted);
  font-size: .9375rem;
  font-weight: 500;
  transition: all .2s;
  border-left: 3px solid transparent;
}

.sidebar-nav a:hover, .sidebar-nav a.active {
  color: var(--ps-primary-light);
  background: rgba(34,197,94,0.08);
  border-left-color: var(--ps-primary);
}

.sidebar-footer {
  padding: 1rem 1.5rem;
  border-top: 1px solid var(--ps-border);
  font-size: .8125rem;
  color: var(--ps-text-muted);
}

.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
}

.topbar {
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 1.5rem;
  border-bottom: 1px solid var(--ps-border);
  background: var(--ps-bg-topbar);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 50;
}

.topbar h1 { font-size: 1.25rem; font-weight: 600; }

.topbar-user { display: flex; align-items: center; gap: .75rem; font-size: .875rem; color: var(--ps-text-muted); }

.theme-toggle, .notif-bell {
  background: transparent;
  border: 1px solid var(--ps-border);
  color: var(--ps-text);
  padding: .4rem .65rem;
  border-radius: 8px;
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  position: relative;
}

.notif-badge {
  position: absolute;
  top: -4px;
  right: -4px;
  background: var(--ps-danger);
  color: #fff;
  font-size: .65rem;
  min-width: 16px;
  height: 16px;
  border-radius: 999px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 4px;
}

.page-content { padding: 1.5rem; max-width: 1400px; }

.menu-toggle {
  display: none;
  background: none;
  border: 1px solid var(--ps-border);
  color: var(--ps-text);
  padding: .5rem .75rem;
  border-radius: 8px;
  cursor: pointer;
}

/* Cards & Grid */
.grid { display: grid; gap: 1.25rem; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--ps-bg-card);
  backdrop-filter: blur(8px);
  border: 1px solid var(--ps-border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.card-title { font-size: 1rem; font-weight: 600; }

.stat-card { text-align: center; }
.stat-card .stat-value { font-size: 2rem; font-weight: 700; color: var(--ps-primary); }
.stat-card .stat-label { font-size: .8125rem; color: var(--ps-text-muted); margin-top: .25rem; }

/* Forms */
.form-group { margin-bottom: 1.25rem; }

.form-group label {
  display: block;
  font-size: .875rem;
  font-weight: 500;
  margin-bottom: .5rem;
  color: var(--ps-text-muted);
}

.form-control {
  width: 100%;
  padding: .75rem 1rem;
  background: var(--ps-bg-input);
  border: 1px solid var(--ps-border);
  border-radius: 8px;
  color: var(--ps-text);
  font-family: inherit;
  font-size: .9375rem;
  transition: border-color .2s;
}

.form-control:focus {
  outline: none;
  border-color: var(--ps-primary);
  box-shadow: 0 0 0 3px rgba(34,197,94,0.15);
}

select.form-control { cursor: pointer; }
textarea.form-control { min-height: 120px; resize: vertical; }

.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  padding: .75rem 1.5rem;
  font-family: inherit;
  font-size: .9375rem;
  font-weight: 600;
  border: none;
  border-radius: 999px;
  cursor: pointer;
  transition: all .2s;
  text-decoration: none;
}

.btn-primary {
  background: linear-gradient(90deg, var(--ps-primary), var(--ps-primary-dark));
  color: #fff;
  box-shadow: 0 4px 16px rgba(34,197,94,0.3);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 24px rgba(34,197,94,0.4);
  color: #fff;
}

.btn-secondary {
  background: transparent;
  border: 1px solid var(--ps-border);
  color: var(--ps-text);
}

.btn-secondary:hover { border-color: var(--ps-primary); color: var(--ps-primary-light); }

.btn-danger { background: var(--ps-danger); color: #fff; }
.btn-sm { padding: .5rem 1rem; font-size: .8125rem; }
.btn-block { width: 100%; }

.btn:disabled, .btn.disabled {
  opacity: .5;
  cursor: not-allowed;
  transform: none !important;
}

/* Table */
.table-wrap { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--ps-border); }

table { width: 100%; border-collapse: collapse; font-size: .875rem; }

thead { background: var(--ps-bg-table-head); }

th, td { padding: .875rem 1rem; text-align: left; border-bottom: 1px solid var(--ps-border); }

th { font-weight: 600; color: var(--ps-text-muted); font-size: .8125rem; text-transform: uppercase; letter-spacing: .03em; }

tr:last-child td { border-bottom: none; }
tr:hover td { background: rgba(34,197,94,0.04); }

.submission-card { margin-bottom: 1rem; }
.submission-header { display: flex; justify-content: space-between; align-items: flex-start; gap: 1rem; flex-wrap: wrap; }
.submission-text { background: var(--ps-bg-input); border: 1px solid var(--ps-border); border-radius: 8px; padding: 1rem; white-space: pre-wrap; }
.submission-grade-form .form-row { align-items: flex-end; }

.auth-theme-toggle {
  position: absolute;
  top: 1rem;
  right: 1rem;
}

/* Badges */
.badge {
  display: inline-block;
  padding: .25rem .625rem;
  border-radius: 999px;
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .03em;
}

.badge-success { background: rgba(34,197,94,0.15); color: var(--ps-success); }
.badge-warning { background: rgba(234,179,8,0.15); color: var(--ps-warning); }
.badge-danger { background: rgba(239,68,68,0.15); color: var(--ps-danger); }
.badge-muted { background: var(--ps-badge-muted-bg); color: var(--ps-text-muted); }

/* Alerts */
.alert {
  padding: 1rem 1.25rem;
  border-radius: 8px;
  margin-bottom: 1.25rem;
  font-size: .9375rem;
}

.alert-success { background: rgba(34,197,94,0.12); border: 1px solid rgba(34,197,94,0.3); color: var(--ps-success); }
.alert-error { background: rgba(239,68,68,0.12); border: 1px solid rgba(239,68,68,0.3); color: var(--ps-danger); }
.alert-info { background: rgba(59,130,246,0.12); border: 1px solid rgba(59,130,246,0.3); color: var(--ps-alert-info-color); }

/* Lock overlay */
.lock-overlay {
  text-align: center;
  padding: 3rem 2rem;
  background: var(--ps-bg-card);
  border: 1px dashed var(--ps-border);
  border-radius: var(--radius);
}

.lock-overlay .lock-icon { font-size: 3rem; margin-bottom: 1rem; opacity: .6; }
.lock-overlay h3 { margin-bottom: .5rem; }
.lock-overlay p { color: var(--ps-text-muted); margin-bottom: 1.5rem; }

/* Live lesson */
.live-lesson-container { display: flex; flex-direction: column; height: calc(100vh - var(--header-height) - 3rem); }
.live-lesson-header { display: flex; align-items: flex-start; justify-content: space-between; margin-bottom: 1rem; gap: 1rem; flex-wrap: wrap; }
.live-lesson-actions { display: flex; gap: .5rem; flex-wrap: wrap; }
.live-lesson-hint { margin-top: .35rem; color: var(--ps-warning); }
#jitsi-container { flex: 1; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--ps-border); min-height: 500px; }
#jitsi-container iframe { width: 100%; height: 100%; border: none; }

body.live-lesson-fullscreen-active { overflow: hidden; }
.live-lesson-container.is-fullscreen {
  position: fixed;
  inset: 0;
  z-index: 9999;
  height: 100vh !important;
  margin: 0;
  padding: .75rem;
  background: var(--ps-bg);
}
.live-lesson-container.is-fullscreen #jitsi-container {
  min-height: 0;
  flex: 1;
  border-radius: 0;
}

/* Course cards */
.course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1.25rem; }

.courses-section-header { margin-bottom: 1rem; }
.courses-section-title { font-size: 1.125rem; margin-bottom: .25rem; }

.course-card {
  background: var(--ps-bg-card);
  border: 1px solid var(--ps-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform .2s, border-color .2s;
}

.course-card:hover { transform: translateY(-2px); border-color: rgba(34,197,94,0.3); }

.course-card-thumb {
  height: 140px;
  background: linear-gradient(135deg, rgba(34,197,94,0.2), var(--ps-card-thumb-end));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
}

.course-card-body { padding: 1.25rem; }
.course-card-body h3 { font-size: 1rem; margin-bottom: .5rem; }
.course-card-body p { font-size: .8125rem; color: var(--ps-text-muted); margin-bottom: 1rem; }
.course-card-footer { display: flex; align-items: center; justify-content: space-between; }
.course-price { font-weight: 700; color: var(--ps-primary); }

.empty-state { text-align: center; padding: 3rem; color: var(--ps-text-muted); }

.page-actions { display: flex; gap: .75rem; margin-bottom: 1.25rem; flex-wrap: wrap; }

.text-muted { color: var(--ps-text-muted); }
.text-small { font-size: .8125rem; }
.mt-1 { margin-top: .5rem; }
.mt-2 { margin-top: 1rem; }
.mb-2 { margin-bottom: 1rem; }

/* Progress, certificates & profile hub */
.progress-bar {
  height: 8px;
  background: var(--ps-badge-muted-bg);
  border-radius: 999px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: var(--ps-primary);
  border-radius: 999px;
  transition: width .3s ease;
}
.progress-course-card { display: flex; flex-direction: column; gap: .75rem; }

.tabs { display: flex; flex-wrap: wrap; gap: .5rem; }
.tab-btn {
  padding: .5rem 1rem;
  border-radius: var(--radius);
  background: var(--ps-badge-muted-bg);
  color: var(--ps-text-muted);
  text-decoration: none;
  font-size: .875rem;
  font-weight: 500;
}
.tab-btn.active { background: var(--ps-primary); color: #fff; }

.profile-hub-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}
.profile-avatar {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--ps-primary);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.125rem;
  flex-shrink: 0;
}
.profile-hub-meta { flex: 1; min-width: 200px; }
.profile-hub-actions { display: flex; gap: .5rem; flex-wrap: wrap; }

.certificate-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1rem;
}
.certificate-card { display: flex; flex-direction: column; gap: .5rem; }

.hint-badge-eligible { background: rgba(34,197,94,0.15); color: var(--ps-success); }
.hint-badge-ineligible { background: rgba(239,68,68,0.15); color: var(--ps-danger); }

.certificate-actions,
.achievement-actions { display: flex; flex-wrap: wrap; gap: .35rem; align-items: flex-start; }
.cert-action-details { display: inline-block; }
.cert-action-details summary { list-style: none; cursor: pointer; }
.cert-action-details summary::-webkit-details-marker { display: none; }
.cert-inline-form {
  margin-top: .5rem;
  padding: .75rem;
  background: var(--ps-badge-muted-bg);
  border-radius: var(--radius);
  min-width: 220px;
}

/* Responsive */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .main-content { margin-left: 0; }
  .menu-toggle { display: block; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .page-content { padding: 1rem; }
  .topbar h1 { font-size: 1rem; }
}

@media (max-width: 480px) {
  .auth-card { padding: 1.5rem; }
  .btn { padding: .625rem 1.25rem; font-size: .875rem; }
}