:root {
  --bg: #f4f7fb;
  --panel: #ffffff;
  --panel-alt: #edf4ff;
  --primary: #234da6;
  --primary-soft: #dfe9ff;
  --text: #162033;
  --muted: #56657d;
  --border: #dfe7f4;
  --correct: #1d8f5f;
  --correct-soft: #eafaf2;
  --wrong: #c64d4d;
  --wrong-soft: #fdecec;
  --warning: #d88a2c;
  --shadow: 0 16px 36px rgba(28, 46, 91, 0.08);
}

* { box-sizing: border-box; }

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

body {
  min-height: 100vh;
}

button, input {
  font: inherit;
}

button {
  cursor: pointer;
}

.auth-page {
  display: grid;
  place-items: center;
  min-height: 100vh;
  background: linear-gradient(135deg, #eef5ff, #f7f5ff 45%, #edfdf7);
}

.auth-shell {
  width: min(100%, 480px);
  padding: 24px;
}

.auth-card, .card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.auth-card {
  padding: 32px;
}

.brand-badge {
  display: inline-flex;
  align-items: center;
  padding: 7px 12px;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary);
  font-weight: 700;
  letter-spacing: 0.04em;
  font-size: 0.8rem;
  text-transform: uppercase;
}

.brand-block h1 {
  margin: 14px 0 8px;
  font-size: clamp(2rem, 4vw, 2.5rem);
}

.brand-block p {
  color: var(--muted);
  margin: 0 0 22px;
}

.login-form {
  display: grid;
  gap: 18px;
}

label {
  display: grid;
  gap: 8px;
  font-weight: 600;
}

input[type="text"], input[type="password"] {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 0.9rem 0.95rem;
  background: #fff;
  color: var(--text);
}

.password-wrap {
  display: flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: #fff;
  overflow: hidden;
}

.password-wrap input {
  border: none;
  border-radius: 0;
}

.toggle-password,
.primary-button,
.secondary-button,
.ghost-button,
.option-button,
.hint-button {
  border: none;
  border-radius: 12px;
  padding: 0.8rem 1rem;
  font-weight: 700;
  transition: transform 0.15s ease, opacity 0.15s ease;
}

.toggle-password {
  background: var(--panel-alt);
  color: var(--primary);
  min-width: 96px;
  border-left: 1px solid var(--border);
}

.primary-button {
  background: var(--primary);
  color: white;
}

.secondary-button {
  background: var(--primary-soft);
  color: var(--primary);
}

.ghost-button {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.primary-button:hover,
.secondary-button:hover,
.ghost-button:hover,
.toggle-password:hover,
.option-button:hover,
.hint-button:hover {
  transform: translateY(-1px);
}

.feedback {
  min-height: 22px;
  margin: 0;
  font-size: 0.95rem;
  color: var(--wrong);
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 22px 32px;
  background: #fff;
  border-bottom: 1px solid var(--border);
  gap: 16px;
}

.topbar h1 {
  margin: 8px 0 0;
  font-size: clamp(1.7rem, 3vw, 2.2rem);
}

.topbar-actions {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
}

.module-tabs {
  display: flex;
  gap: 10px;
  padding: 18px 32px 0;
  flex-wrap: wrap;
}

.module-tab {
  border: 1px solid var(--border);
  border-radius: 999px;
  background: #fff;
  color: var(--muted);
  padding: 0.7rem 1rem;
  font-weight: 700;
}

.module-tab.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.study-layout {
  display: grid;
  grid-template-columns: minmax(220px, 300px) minmax(0, 1fr);
  gap: 22px;
  padding: 22px 32px 48px;
}

.main-panel {
  grid-column: 2;
}

.demo-notice {
  margin: 16px 32px 0;
  padding: 12px 16px;
  border: 1px solid #f2d2a7;
  border-radius: 12px;
  background: #fff8ed;
  color: #7a4b00;
}

.sidebar {
  padding: 18px 18px 22px;
  align-self: start;
}

.sidebar h2, .sidebar h3 {
  margin-top: 0;
}

.summary-list {
  display: grid;
  gap: 12px;
  margin-bottom: 18px;
}

.summary-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 12px;
  background: var(--panel-alt);
  border-radius: 10px;
}

.topic-list {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  display: grid;
  gap: 8px;
}

.main-panel {
  display: grid;
  gap: 22px;
}

.card {
  padding: 22px 20px;
}

.eyebrow {
  margin: 0 0 6px;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--primary);
  font-weight: 700;
}

.welcome-card h2, .quiz-panel h2, .card h2 {
  margin: 0 0 10px;
}

.quiz-intro p {
  color: var(--muted);
}

.quiz-container {
  display: grid;
  gap: 20px;
}

.question-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  background: #fff;
  padding: 18px;
}

.question-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-size: 0.86rem;
  margin-bottom: 12px;
}

.question-card h3 {
  margin: 0 0 14px;
  font-size: 1.1rem;
  line-height: 1.5;
}

.question-instruction {
  color: var(--muted);
  margin: -4px 0 14px;
}

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

.option-button {
  width: 100%;
  text-align: left;
  background: #f7f9fc;
  border: 1px solid var(--border);
  color: var(--text);
}

.option-button.selected {
  background: var(--primary-soft);
  border-color: var(--primary);
  color: var(--primary);
}

.option-button.correct {
  background: var(--correct-soft);
  border-color: var(--correct);
  color: var(--correct);
}

.option-button.wrong {
  background: var(--wrong-soft);
  border-color: var(--wrong);
  color: var(--wrong);
}

.hint-button {
  background: #fff8ed;
  color: var(--warning);
  border: 1px solid #f2d2a7;
  margin-top: 10px;
}

.hint-box {
  margin-top: 10px;
  padding: 10px 12px;
  border-radius: 10px;
  background: #fff8ed;
  color: #7a4b00;
}

.quiz-results {
  display: grid;
  gap: 14px;
  margin-top: 20px;
}

.quiz-result-item {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
}

.quiz-result-item.correct {
  border-color: rgba(29, 143, 95, 0.42);
  background: var(--correct-soft);
}

.quiz-result-item.incorrect {
  border-color: rgba(198, 77, 77, 0.38);
  background: var(--wrong-soft);
}

.quiz-actions {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  margin-top: 18px;
  flex-wrap: wrap;
}

.hidden {
  display: none !important;
}

.feedback-panel {
  margin-top: 16px;
  border-radius: 12px;
  padding: 14px 16px;
}

.feedback-panel.correct {
  background: var(--correct-soft);
  color: #0a5f3f;
}

.feedback-panel.wrong {
  background: var(--wrong-soft);
  color: #8d2e2e;
}

.answer-grid {
  display: grid;
  gap: 16px;
}

.review-item {
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 16px;
  background: #fff;
}

.review-item.correct {
  border-color: rgba(29, 143, 95, 0.42);
}

.review-item.incorrect {
  border-color: rgba(198, 77, 77, 0.38);
}

.review-item h4 {
  margin: 0 0 10px;
}

.flashcards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
}

.flashcard {
  border: 1px solid var(--border);
  background: linear-gradient(180deg, #ffffff, #f6f9ff);
  border-radius: 14px;
  padding: 16px;
}

.flashcard h4 {
  margin-top: 0;
}

.flashcard p {
  margin-bottom: 0;
  color: var(--muted);
}

@media (max-width: 860px) {
  .topbar,
  .study-layout,
  .module-tabs {
    padding-left: 16px;
    padding-right: 16px;
  }

  .study-layout {
    grid-template-columns: 1fr;
  }

  .main-panel {
    grid-column: 1;
  }

  .demo-notice {
    margin-left: 16px;
    margin-right: 16px;
  }

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

  .topbar-actions {
    width: 100%;
  }
}