.board {
  background:
    radial-gradient(circle at 78% 16%, rgba(117, 70, 235, .08), transparent 27%),
    linear-gradient(145deg, #fbfaff 0%, #f7f8ff 48%, #fbfdff 100%);
}

.lesson-canvas {
  position: absolute;
  inset: clamp(26px, 5%, 54px) clamp(32px, 8%, 92px) clamp(24px, 5%, 48px) clamp(76px, 10%, 116px);
  display: flex;
  flex-direction: column;
  max-width: 920px;
  margin: auto;
  padding: clamp(22px, 3vw, 36px);
  overflow: auto;
  border: 1px solid #e2def0;
  border-radius: 24px;
  background: rgba(255, 255, 255, .96);
  box-shadow: 0 24px 65px rgba(44, 33, 91, .12);
}

.lesson-canvas-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
  padding-bottom: 20px;
  border-bottom: 1px solid #ebe8f3;
}

.lesson-canvas-head h2 {
  margin: 2px 0 5px;
  color: var(--ink);
  font-size: clamp(20px, 2vw, 28px);
  letter-spacing: -1px;
}

.lesson-canvas-head p {
  margin: 0;
  color: var(--muted);
  font-size: 10px;
}

.lesson-status {
  flex: 0 0 auto;
  padding: 7px 11px;
  border: 1px solid #d9cdf8;
  border-radius: 999px;
  color: #6031c7;
  background: #f5f0ff;
  font-size: 8px;
  font-weight: 800;
}

.lesson-board-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(260px, .95fr);
  gap: 18px;
  margin-top: 20px;
}

.exercise-card,
.steps-card {
  min-width: 0;
  padding: clamp(18px, 2.3vw, 28px);
  border: 1px solid #e7e3f1;
  border-radius: 18px;
  background: #fff;
}

.exercise-card {
  position: relative;
  overflow: hidden;
  background: linear-gradient(150deg, #faf7ff, #f4f7ff);
}

.exercise-card::after {
  content: '✦';
  position: absolute;
  right: -8px;
  top: -24px;
  color: rgba(106, 42, 226, .08);
  font-size: 112px;
}

.exercise-label {
  position: relative;
  z-index: 1;
  color: var(--violet);
  font-size: 8px;
  font-weight: 800;
  letter-spacing: 1px;
}

.exercise-card h3 {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 14px 0 22px;
  font-size: clamp(18px, 2vw, 25px);
  letter-spacing: -.8px;
}

.inline-fraction {
  width: 28px;
  display: inline-grid;
  place-items: center;
  line-height: 1;
}

.inline-fraction b {
  font-size: 16px;
}

.inline-fraction i {
  width: 100%;
  height: 2px;
  margin: 3px 0;
  border-radius: 99px;
  background: var(--ink);
}

.fraction-visual {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 7px;
}

.fraction-visual i {
  height: clamp(54px, 7vw, 80px);
  border: 2px solid #d9d4e7;
  border-radius: 13px;
  background: #fff;
}

.fraction-visual i:nth-child(-n+3) {
  border-color: #7030e8;
  background: linear-gradient(155deg, #a62ce3, #7030eb 58%, #3488ef);
  box-shadow: 0 9px 22px rgba(104, 45, 222, .17);
}

.exercise-card p {
  position: relative;
  z-index: 1;
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 9px;
}

.steps-card {
  display: flex;
  flex-direction: column;
}

.math-step {
  display: grid;
  grid-template-columns: 30px 1fr auto;
  align-items: center;
  gap: 11px;
  padding: 13px 0;
  border-bottom: 1px solid #efedf5;
}

.math-step > i {
  width: 28px;
  height: 28px;
  display: grid;
  place-items: center;
  border-radius: 9px;
  color: var(--violet);
  background: #f0e9ff;
  font-size: 9px;
  font-style: normal;
  font-weight: 800;
}

.math-step b,
.math-step small {
  display: block;
}

.math-step b {
  color: var(--ink);
  font-size: 11px;
}

.math-step small {
  margin-top: 2px;
  color: var(--muted);
  font-size: 7px;
}

.math-step strong {
  color: #4c4cda;
  font-size: 15px;
}

.answer-card {
  margin-top: auto;
  padding: 13px 14px;
  display: grid;
  grid-template-columns: 1fr auto auto;
  align-items: center;
  gap: 10px;
  border: 1px solid #bfe9d6;
  border-radius: 13px;
  background: #effbf5;
}

.answer-card span {
  color: #33755c;
  font-size: 8px;
  font-weight: 800;
}

.answer-card b {
  color: #0d8656;
  font-size: 22px;
}

.answer-card i {
  width: 25px;
  height: 25px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: #19a66b;
  font-style: normal;
  font-weight: 800;
}

.teacher-feedback {
  position: relative;
  margin-top: 18px;
  padding: 14px 17px;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 12px;
  overflow: hidden;
  border: 1px solid #ded7f3;
  border-radius: 16px;
  background: linear-gradient(105deg, #fbf8ff, #f3f7ff);
}

.teacher-feedback::after {
  content: '✦';
  position: absolute;
  right: 15%;
  color: rgba(109, 40, 225, .07);
  font-size: 60px;
}

.feedback-avatar {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 11px;
  color: #fff;
  background: linear-gradient(135deg, var(--violet), var(--blue));
  font-size: 10px;
  font-weight: 800;
}

.teacher-feedback b,
.teacher-feedback p {
  position: relative;
  z-index: 1;
}

.teacher-feedback b {
  font-size: 10px;
}

.teacher-feedback p {
  margin: 3px 0 0;
  color: var(--muted);
  font-size: 8px;
}

.feedback-time {
  position: relative;
  z-index: 1;
  color: #7b7591;
  font-size: 7px;
}

.room-chat-preview {
  margin: 10px;
  padding: 10px;
  align-self: flex-start;
  border-radius: 10px 10px 10px 3px;
  color: #23314c;
  background: #fff;
}

.lesson-chat .room-chat-preview p {
  margin: 0;
  padding: 0;
  color: #23314c;
  text-align: left;
  font-size: 7px;
}

.room-chat-preview small {
  display: block;
  margin-top: 4px;
  color: #6b7690;
  font-size: 6px;
}

@media (max-width: 1050px) {
  .lesson-canvas {
    right: 28px;
    padding: 22px;
  }

  .lesson-board-grid {
    grid-template-columns: 1fr;
  }

  .fraction-visual i {
    height: 48px;
  }
}

@media (max-width: 800px) {
  .lesson-canvas {
    inset: 18px 18px 18px 64px;
    padding: 18px;
  }

  .lesson-canvas-head p,
  .teacher-feedback p,
  .feedback-time {
    display: none;
  }

  .lesson-board-grid {
    gap: 12px;
    margin-top: 14px;
  }

  .exercise-card,
  .steps-card {
    padding: 15px;
  }

  .exercise-card h3 {
    margin: 8px 0 12px;
    font-size: 17px;
  }

  .fraction-visual i {
    height: 34px;
  }

  .teacher-feedback {
    margin-top: 12px;
    padding: 10px;
  }
}

@media (max-width: 480px) {
  .lesson-status {
    display: none;
  }

  .lesson-canvas {
    inset: 12px 10px 12px 58px;
    border-radius: 16px;
  }
}