:root {
  color-scheme: light;
  --bg: #f3f5f9;
  --panel: #ffffff;
  --text: #17212f;
  --muted: #5d6878;
  --line: #d7deea;
  --blue: #2563eb;
  --blue-dark: #1e4fba;
  --green: #159f6b;
  --red: #c0392b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
}

.landing-screen {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  overflow: hidden;
  z-index: 100;
}

.landing-bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.landing-overlay {
  position: relative;
  z-index: 1;
  text-align: center;
  color: #ffffff;
  background: rgba(0, 0, 0, 0.42);
  border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: 8px;
  padding: 24px 20px;
  width: min(92vw, 520px);
  transform: translateY(clamp(90px, 16vh, 150px));
}

.landing-logo {
  width: 94px;
  height: 94px;
  object-fit: contain;
  border-radius: 16px;
  background: #ffffff;
  padding: 6px;
}

.landing-logo-corner {
  position: absolute;
  top: 24px;
  left: 24px;
  z-index: 2;
}

.landing-overlay h1 {
  margin: 6px 0;
}

.landing-overlay p {
  margin: 0 0 14px;
}

.app-shell {
  max-width: 1200px;
  margin: 0 auto;
  padding: 16px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
}

.topbar h1 {
  margin: 0;
  font-size: 1.6rem;
}

.header-logo {
  width: 44px;
  height: 44px;
  object-fit: contain;
  border-radius: 8px;
  border: 1px solid var(--line);
  display: block;
  margin-bottom: 8px;
}

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

.topbar-actions {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
}

.install-help {
  margin: 0;
  max-width: 280px;
  text-align: right;
  font-size: 0.82rem;
}

.role-switch {
  display: flex;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

.mode-btn {
  border: 0;
  background: #f4f7fc;
  color: var(--text);
  padding: 10px 16px;
  font-weight: 600;
  cursor: pointer;
}

.mode-btn.active {
  background: var(--blue);
  color: #fff;
}

.layout {
  margin-top: 16px;
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 16px;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
}

.subjects-panel h2,
.content-panel h2 {
  margin-top: 0;
}

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

.subject-btn {
  text-align: left;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  color: var(--text);
  padding: 12px;
  cursor: pointer;
}

.subject-btn.active {
  border-color: var(--blue);
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.15);
}

.subject-btn h3 {
  margin: 0 0 4px;
  font-size: 1rem;
  color: var(--text);
}

.subject-btn p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.empty-state {
  color: var(--muted);
  padding: 24px;
  border: 1px dashed var(--line);
  border-radius: 8px;
}

.subject-header h2 {
  margin-bottom: 6px;
}

.subject-header p {
  margin-top: 0;
  color: var(--muted);
}

#studentView #topicStatus,
#studentView #levelStatus {
  display: none;
}

.topic-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 6px;
}

.topic-row label {
  font-weight: 600;
}

.topic-row select {
  margin-bottom: 0;
  max-width: 620px;
}

.split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.tutorial-card,
.quiz-card,
.inline-panel {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
}

.selected-skill-progress {
  margin-bottom: 14px;
}

select,
button {
  font: inherit;
}

select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 8px;
  margin-bottom: 10px;
}

.tutorial-body p {
  margin: 0 0 10px;
  line-height: 1.5;
}

.tutorial-body ol {
  margin: 0;
  padding-left: 18px;
}

.tutorial-body li {
  margin-bottom: 8px;
}

.video-links {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
}

.video-links h4 {
  margin: 0 0 6px;
}

.video-links p {
  margin: 0 0 10px;
  color: var(--muted);
  font-size: 0.9rem;
}

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

.video-link-card {
  display: block;
  border: 1px solid #c9dafb;
  border-radius: 8px;
  background: #f5f8ff;
  color: var(--text);
  padding: 10px;
  text-decoration: none;
}

.video-link-card:hover {
  border-color: var(--blue);
  background: #eef4ff;
}

.video-link-title {
  display: block;
  font-weight: 700;
  color: var(--blue-dark);
}

.video-link-meta {
  display: block;
  margin-top: 3px;
  color: var(--muted);
  font-size: 0.82rem;
}

.meta {
  color: var(--muted);
  font-size: 0.9rem;
}

.question {
  font-weight: 600;
  line-height: 1.4;
}

.choices {
  display: grid;
  gap: 8px;
  margin-bottom: 8px;
}

.short-answer-wrap {
  display: flex;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
}

.short-answer-wrap input {
  flex: 1;
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 10px;
}

.choice-btn {
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 10px;
  text-align: left;
  background: #fff;
  color: var(--text);
  cursor: pointer;
}

.choice-btn:hover {
  background: #f4f7fc;
  color: var(--text);
}

.choice-btn.correct {
  border-color: var(--green);
  background: #ecfbf4;
  color: var(--text);
}

.choice-btn.incorrect {
  border-color: var(--red);
  background: #fff1ef;
  color: var(--text);
}

.feedback {
  min-height: 24px;
  font-weight: 600;
}

.hint-box {
  border: 1px solid #c9dafb;
  border-radius: 6px;
  background: #eef4ff;
  color: #223659;
  padding: 10px;
  margin-top: 10px;
  margin-bottom: 8px;
}

.quiz-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

button {
  border: 1px solid var(--blue);
  background: var(--blue);
  color: white;
  border-radius: 6px;
  padding: 8px 12px;
  cursor: pointer;
}

button:hover {
  background: var(--blue-dark);
}

button.secondary {
  background: #fff;
  color: var(--blue);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.parent-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-bottom: 14px;
}

.summary-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
}

.summary-card h3 {
  margin: 0 0 8px;
}

.summary-card p {
  margin: 4px 0;
}

.hidden {
  display: none !important;
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .split {
    grid-template-columns: 1fr;
  }

  .parent-summary {
    grid-template-columns: 1fr;
  }
}

@media (max-height: 650px) {
  .landing-overlay {
    transform: translateY(80px);
  }
}