:root {
  --bg: #f7f4ed;
  --card: #ffffff;
  --text: #243044;
  --muted: #6c768a;
  --primary: #4f7cff;
  --primary-dark: #385fd1;
  --soft: #e9efff;
  --success: #16825d;
  --danger: #bd3b3b;
  --border: #e0e5ef;
  --shadow: 0 18px 40px rgba(44, 55, 82, 0.12);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: Arial, Helvetica, sans-serif;
  background: radial-gradient(circle at top left, #eaf1ff 0, #f7f4ed 42%, #fff8ef 100%);
  color: var(--text);
}

.app-shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 28px 0 56px;
}

.hero {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: stretch;
  padding: 34px;
  border-radius: 30px;
  background: linear-gradient(135deg, #ffffff, #eef4ff);
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0 0 8px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--primary-dark);
  font-weight: 700;
  font-size: 12px;
}

h1, h2, h3 { margin-top: 0; }
h1 { font-size: clamp(34px, 6vw, 58px); margin-bottom: 12px; }
h2 { font-size: clamp(26px, 4vw, 38px); }
h3 { font-size: 22px; }

.subtitle {
  max-width: 680px;
  line-height: 1.65;
  color: var(--muted);
  font-size: 18px;
  margin: 0;
}

.hero-card {
  min-width: 170px;
  border-radius: 24px;
  background: var(--text);
  color: white;
  display: grid;
  place-items: center;
  padding: 24px;
  text-align: center;
}

.hero-card span { font-size: 58px; font-weight: 800; line-height: 1; }
.hero-card p { margin: 8px 0 0; color: #dce6ff; }

.tabs {
  display: flex;
  gap: 12px;
  margin: 24px 0;
  flex-wrap: wrap;
}

.tab, button {
  border: none;
  cursor: pointer;
  font-weight: 700;
  transition: transform 0.2s ease, background 0.2s ease, opacity 0.2s ease;
}

button:hover { transform: translateY(-1px); }
button:disabled { opacity: 0.5; cursor: not-allowed; transform: none; }

.tab {
  padding: 13px 18px;
  border-radius: 999px;
  background: var(--card);
  color: var(--muted);
  box-shadow: 0 8px 20px rgba(44, 55, 82, 0.08);
}

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

.screen { display: none; }
.screen.active { display: block; }

section, .question-editor, .quiz-card, .results-hero {
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  border-radius: 28px;
  padding: 28px;
}

.section-heading {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: center;
  margin-bottom: 24px;
}
.section-heading p { color: var(--muted); margin: 0; }
.section-heading.compact { margin-top: 26px; }

.form-grid, .answers-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.question-editor { margin-top: 22px; }

label {
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 16px;
}

input, textarea, select {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 13px 14px;
  font: inherit;
  color: var(--text);
  background: white;
  outline: none;
}

input:focus, textarea:focus, select:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 4px var(--soft);
}

.primary-button, .secondary-button {
  padding: 13px 18px;
  border-radius: 16px;
}

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

.button-row { display: flex; gap: 12px; flex-wrap: wrap; align-items: center; }
.centered { justify-content: center; }

.questions-list, .correction-list {
  display: grid;
  gap: 14px;
}

.question-item, .correction-item {
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 18px;
  background: white;
}

.question-item-header {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: flex-start;
}

.question-item p, .correction-item p { color: var(--muted); line-height: 1.55; }
.small-actions { display: flex; gap: 8px; flex-wrap: wrap; }
.small-actions button { padding: 8px 11px; border-radius: 12px; background: #f2f5fb; color: var(--text); }

.quiz-card { max-width: 820px; margin: 0 auto; }
.progress-line { display: flex; justify-content: space-between; gap: 14px; color: var(--muted); font-weight: 700; margin-bottom: 12px; }
.progress-bar { height: 12px; border-radius: 999px; background: #edf1f7; overflow: hidden; margin-bottom: 28px; }
#progress-fill { height: 100%; width: 10%; background: var(--primary); border-radius: inherit; transition: width 0.3s ease; }

.answer-options { display: grid; gap: 12px; margin: 24px 0; }
.answer-option {
  text-align: left;
  padding: 16px;
  border: 1px solid var(--border);
  background: white;
  border-radius: 18px;
  color: var(--text);
}
.answer-option.selected { border-color: var(--primary); background: var(--soft); }
.quiz-actions { justify-content: space-between; }

.results-hero { text-align: center; margin-bottom: 22px; }
.result-stats {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin: 18px 0 22px;
}
.result-stats span {
  background: var(--soft);
  color: var(--primary-dark);
  padding: 10px 14px;
  border-radius: 999px;
  font-weight: 800;
}
.badge-correct { color: var(--success); font-weight: 800; }
.badge-wrong { color: var(--danger); font-weight: 800; }

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(20, 28, 50, 0.55);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 20px;
}

.modal-card {
  background: white;
  border-radius: 28px;
  padding: clamp(28px, 5vw, 48px);
  box-shadow: 0 32px 80px rgba(20, 28, 50, 0.22);
  max-width: 480px;
  width: 100%;
}

.modal-card h2 { font-size: clamp(22px, 4vw, 30px); margin-bottom: 8px; }

.modal-subtitle { color: var(--muted); margin: 0 0 24px; line-height: 1.5; }

.modal-fields {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 20px;
}

.student-name-display {
  font-size: clamp(16px, 2vw, 20px);
  font-weight: 700;
  color: var(--primary-dark);
  margin: 0 0 4px;
}

.import-zone {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  background: linear-gradient(135deg, #f0f5ff, #fafbff);
  border: 2px dashed var(--primary);
  border-radius: 22px;
  padding: 22px 24px;
  margin-bottom: 8px;
}

.import-zone-left {
  flex: 1;
  min-width: 200px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.import-zone-left strong { font-size: 16px; }
.import-zone-left span { color: var(--muted); font-size: 14px; }
.import-zone-left code { background: var(--soft); padding: 1px 5px; border-radius: 6px; font-size: 13px; }

.import-zone-right {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.import-label {
  display: inline-flex;
  align-items: center;
  cursor: pointer;
  font-weight: 700;
  font-size: 14px;
}

.import-feedback {
  width: 100%;
  padding: 10px 14px;
  border-radius: 12px;
  font-weight: 700;
  font-size: 14px;
}

.import-feedback--success { background: #e6f7f1; color: var(--success); }
.import-feedback--error { background: #fdeaea; color: var(--danger); }

@media (max-width: 760px) {
  .app-shell { width: min(100% - 20px, 1120px); padding-top: 12px; }
  .hero, .section-heading, .question-item-header { flex-direction: column; }
  .hero, section, .question-editor, .quiz-card, .results-hero { padding: 20px; border-radius: 22px; }
  .hero-card { width: 100%; }
  .form-grid, .answers-grid, .modal-fields { grid-template-columns: 1fr; }
  .progress-line { flex-direction: column; }
}