:root {
  --green: #18864b;
  --green-soft: #e3f5eb;
  --yellow: #d59b00;
  --yellow-soft: #fff4c7;
  --black: #171717;
  --ink: #1f2933;
  --muted: #667085;
  --line: #d8dee8;
  --surface: #ffffff;
  --page: #f6f8fb;
  --accent: #2457c5;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--page);
  color: var(--ink);
}

button, input, textarea, select {
  font: inherit;
}

button {
  border: 0;
  border-radius: 8px;
  background: var(--black);
  color: white;
  padding: 0.75rem 1rem;
  cursor: pointer;
  font-weight: 700;
}

button.secondary {
  background: #edf1f7;
  color: var(--black);
}

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

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

input, textarea, select {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.75rem;
  background: white;
  color: var(--ink);
}

textarea {
  min-height: 92px;
  resize: vertical;
}

.shell {
  min-height: 100vh;
}

.topbar {
  background: #0f1720;
  color: white;
  padding: 1rem clamp(1rem, 4vw, 3rem);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.brand {
  font-weight: 900;
  letter-spacing: 0;
}

.nav {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.nav button {
  background: rgba(255, 255, 255, 0.12);
  padding: 0.55rem 0.8rem;
}

.page {
  width: min(1180px, calc(100% - 2rem));
  margin: 1.5rem auto 3rem;
}

.center {
  min-height: calc(100vh - 72px);
  display: grid;
  place-items: center;
  padding: 1rem;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: clamp(1rem, 3vw, 2rem);
  box-shadow: 0 18px 50px rgba(16, 24, 40, 0.08);
}

.login-panel {
  width: min(520px, 100%);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
}

.card {
  background: white;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 1rem;
}

.day-card {
  display: grid;
  gap: 0.85rem;
}

.student-progress-list {
  display: grid;
  gap: 1rem;
}

.day-progress-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 0.75rem;
}

.day-progress-cell {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.85rem;
  background: #f8fafc;
}

.day-progress-cell.completed {
  background: var(--green-soft);
  border-color: var(--green);
}

.access-code-list {
  display: grid;
  gap: 0.45rem;
  margin-top: 0.6rem;
}

.muted {
  color: var(--muted);
}

.row {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  flex-wrap: wrap;
}

.between {
  justify-content: space-between;
}

.progress-track {
  width: 100%;
  height: 12px;
  background: #e6ebf2;
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--green);
  width: 0%;
}

.question-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 1rem;
}

.question-text {
  font-size: clamp(1.25rem, 2vw, 1.8rem);
  font-weight: 850;
  line-height: 1.2;
}

.question-image {
  display: block;
  width: 100%;
  max-width: 100%;
  max-height: 340px;
  object-fit: contain;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: white;
}

.question-image-placeholder {
  min-height: 220px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background:
    linear-gradient(135deg, rgba(24, 134, 75, 0.12), rgba(36, 87, 197, 0.08)),
    #ffffff;
  display: grid;
  place-items: center;
  gap: 0.85rem;
  color: var(--ink);
  overflow: hidden;
  position: relative;
}

.visual-grid {
  display: grid;
  grid-template-columns: repeat(4, 44px);
  gap: 10px;
}

.visual-grid span {
  width: 44px;
  height: 34px;
  border-radius: 6px;
  border: 1px solid rgba(31, 41, 51, 0.14);
  background: rgba(255, 255, 255, 0.72);
}

.visual-grid span:nth-child(2),
.visual-grid span:nth-child(5),
.visual-grid span:nth-child(7) {
  background: var(--green-soft);
  border-color: rgba(24, 134, 75, 0.35);
}

.visual-grid span:nth-child(3),
.visual-grid span:nth-child(8) {
  background: var(--yellow-soft);
  border-color: rgba(213, 155, 0, 0.35);
}

.feedback {
  background: #f8fafc;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 1rem;
}

.word-hints {
  display: grid;
  gap: 0.75rem;
}

.word-hint {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.75rem;
  background: white;
}

.word-hint.correct {
  border-color: var(--green);
  background: var(--green-soft);
}

.word-hint.partial,
.word-hint.missing {
  border-color: var(--yellow);
  background: var(--yellow-soft);
}

.word-hint.extra {
  border-color: var(--black);
}

.typed-word {
  margin-top: 0.55rem;
  min-height: 2rem;
}

.review-list {
  display: flex;
  gap: 0.45rem;
  flex-wrap: wrap;
}

.review-button {
  min-width: 2.5rem;
  padding: 0.5rem 0.65rem;
  background: #edf1f7;
  color: var(--black);
}

.review-button.active {
  background: var(--green);
  color: white;
}

.review-answer {
  margin: 0;
  padding: 0.85rem;
  border-radius: 8px;
  background: var(--green-soft);
  color: var(--green);
  font-weight: 850;
}

.review-answer-list {
  margin: 0;
  padding: 0.85rem 0.85rem 0.85rem 2rem;
  border-radius: 8px;
  background: var(--green-soft);
}

.char {
  display: inline-block;
  min-width: 0.72rem;
  padding: 0.12rem 0.18rem;
  margin: 0.08rem;
  border-radius: 4px;
  font-weight: 800;
}

.correct {
  color: var(--green);
  background: var(--green-soft);
}

.partial, .missing {
  color: #8a6400;
  background: var(--yellow-soft);
}

.incorrect {
  color: white;
  background: var(--black);
}

.option {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.65rem;
  align-items: start;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 0.75rem;
  background: white;
}

.option input {
  width: auto;
  margin-top: 0.2rem;
}

.option.correct {
  border-color: var(--green);
}

.option.missing {
  border-color: var(--yellow);
}

.option.incorrect {
  border-color: var(--black);
}

.tabs {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin: 1rem 0;
}

.tabs button.active {
  background: var(--accent);
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: white;
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

th, td {
  padding: 0.75rem;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
  white-space: nowrap;
}

th {
  background: #eef2f7;
  font-size: 0.9rem;
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.85rem;
}

.stack {
  display: grid;
  gap: 1rem;
}

.small {
  font-size: 0.9rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  min-height: 1.75rem;
  padding: 0.25rem 0.55rem;
  border-radius: 999px;
  font-weight: 800;
  background: #edf1f7;
}

.badge.done {
  color: var(--green);
  background: var(--green-soft);
}

.badge.todo {
  color: #8a6400;
  background: var(--yellow-soft);
}

.error {
  color: #b42318;
  font-weight: 700;
}

.success {
  color: var(--green);
  font-weight: 800;
}

button:disabled {
  cursor: wait;
  opacity: 0.65;
}

@media (max-width: 800px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
  }

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

  th, td {
    white-space: normal;
  }
}