:root {
  --bg: #000000;
  --surface: #111111;
  --text: #f5f5f5;
  --muted: #a8a8a8;
  --border: #2a2a2a;
  --input-bg: #1a1a1a;
  --primary: #ffffff;
  --primary-text: #000000;
  --secondary: #1f1f1f;
  --secondary-text: #f0f0f0;
  --shadow: 0 18px 40px rgba(0, 0, 0, 0.45);
}

body[data-theme="light"] {
  --bg: #f4f5f7;
  --surface: #ffffff;
  --text: #151515;
  --muted: #555555;
  --border: #dddddd;
  --input-bg: #fbfbfb;
  --primary: #111111;
  --primary-text: #ffffff;
  --secondary: #ececec;
  --secondary-text: #151515;
  --shadow: 0 14px 32px rgba(0, 0, 0, 0.1);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  transition: background-color 0.25s ease, color 0.25s ease;
}

.top-bar {
  display: flex;
  justify-content: flex-end;
  padding: 20px;
}

.theme-toggle {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 14px;
  font-size: 0.92rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.theme-toggle:hover {
  transform: translateY(-1px);
  border-color: var(--text);
}

.container {
  min-height: calc(100vh - 72px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.card {
  width: min(420px, 100%);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  box-shadow: var(--shadow);
}

.auth-card h1 {
  margin: 0 0 8px;
  font-size: 1.6rem;
}

.subtitle {
  margin: 0 0 24px;
  color: var(--muted);
}

.form {
  display: grid;
  gap: 12px;
}

.form label {
  font-size: 0.95rem;
}

.form input,
.form select,
.form textarea {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--input-bg);
  color: var(--text);
  outline: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.form input:focus,
.form select:focus,
.form textarea:focus {
  border-color: var(--text);
  box-shadow: 0 0 0 3px rgba(127, 127, 127, 0.2);
}

.login-button {
  margin-top: 8px;
  border: none;
  border-radius: 10px;
  padding: 12px;
  font-weight: 600;
  background: var(--primary);
  color: var(--primary-text);
  cursor: pointer;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.login-button:hover {
  transform: translateY(-1px);
  opacity: 0.92;
}

.secondary-button {
  margin-top: 6px;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 11px;
  font-weight: 600;
  background: var(--secondary);
  color: var(--secondary-text);
  cursor: pointer;
  text-decoration: none;
  text-align: center;
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.secondary-button:hover {
  transform: translateY(-1px);
  border-color: var(--text);
}

.form-links {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-top: 16px;
}

.form-links a {
  color: var(--muted);
  font-size: 0.92rem;
  text-decoration: none;
}

.form-links a:hover {
  color: var(--text);
  text-decoration: underline;
}

.feedback {
  margin: 0 0 14px;
  color: var(--muted);
  font-size: 0.92rem;
  min-height: 18px;
}

.dashboard-container {
  max-width: 980px;
  margin: 0 auto;
  padding: 8px 20px 30px;
}

.dashboard-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
}

.dashboard-header h1 {
  margin: 0;
  font-size: 1.7rem;
}

.dashboard-header p {
  margin: 6px 0 0;
  color: var(--muted);
}

.dashboard-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 14px;
}

.stat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  box-shadow: var(--shadow);
}

.stat-title {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
}

.stat-value {
  margin: 8px 0 0;
  font-size: 1.9rem;
  font-weight: 700;
}

.panel {
  margin-top: 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
  box-shadow: var(--shadow);
}

.panel h2 {
  margin: 0 0 12px;
  font-size: 1.2rem;
}

.form-inline {
  display: grid;
  gap: 10px;
}

.form-inline .login-button {
  margin-top: 0;
}

.course-list {
  display: grid;
  gap: 12px;
}

.course-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--input-bg);
  padding: 14px;
}

.course-item h3 {
  margin: 0 0 5px;
}

.course-description {
  margin: 0 0 10px;
  color: var(--muted);
}

.module-list {
  display: grid;
  gap: 10px;
}

.module-item {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  background: var(--surface);
}

.module-item h4 {
  margin: 0 0 8px;
}

.chapter-list {
  display: grid;
  gap: 8px;
}

.chapter-item {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px;
  background: var(--input-bg);
}

.chapter-item strong {
  display: block;
  margin-bottom: 7px;
}

.youtube-link {
  color: var(--text);
  font-size: 0.92rem;
}

.empty-state {
  margin: 0;
  color: var(--muted);
}

.video-frame {
  width: 100%;
  border: 0;
  border-radius: 10px;
  aspect-ratio: 16 / 9;
  background: #000;
}

.class-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.class-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px;
  background: var(--input-bg);
}

.class-item strong {
  display: block;
  margin-bottom: 5px;
}

.class-item span {
  color: var(--muted);
  font-size: 0.93rem;
}

@media (max-width: 640px) {
  .top-bar {
    padding: 14px;
  }

  .dashboard-container {
    padding: 0 14px 18px;
  }

  .dashboard-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .secondary-button {
    width: 100%;
  }
}