* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Sarabun", sans-serif;
  background: linear-gradient(135deg, #eef7f0, #f9fbf2);
  color: #183320;
}

#app {
  max-width: 980px;
  margin: 0 auto;
  padding: 24px;
}

.card {
  background: #ffffff;
  margin-top: 40px;
  padding: 32px;
  border-radius: 24px;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.08);
}

.hidden {
  display: none !important;
}

h1, h2 {
  margin-top: 0;
  color: #12351f;
}

.subtitle {
  color: #5d6f63;
  margin-bottom: 28px;
}

label {
  display: block;
  margin-bottom: 8px;
  font-weight: 700;
}

input,
select {
  width: 100%;
  padding: 14px 16px;
  border: 1px solid #c8d6cc;
  border-radius: 14px;
  font-size: 18px;
  font-family: inherit;
  margin-bottom: 18px;
  background: white;
}

button {
  border: none;
  background: #0f6b3d;
  color: white;
  padding: 14px 24px;
  border-radius: 14px;
  font-size: 17px;
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
}

button:hover {
  background: #0b5731;
}

button:disabled {
  background: #9aa59d;
  cursor: not-allowed;
}

.message {
  color: #b00020;
  font-weight: 700;
}

.student-box {
  background: #eef7f0;
  padding: 16px 20px;
  border-radius: 16px;
  margin: 24px 0;
}

.exam-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: #ffffff;
  border-radius: 0 0 20px 20px;
  padding: 18px 22px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.08);
}

.timer {
  background: #ffe7e7;
  color: #a50000;
  padding: 12px 16px;
  border-radius: 14px;
  font-weight: 700;
  white-space: nowrap;
}

.question-card {
  background: #ffffff;
  padding: 24px;
  border-radius: 20px;
  margin-bottom: 20px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

.question-title {
  font-weight: 700;
  margin-bottom: 18px;
  line-height: 1.8;
}

.choice {
  display: block;
  padding: 12px 14px;
  border: 1px solid #d7e2da;
  border-radius: 14px;
  margin-bottom: 10px;
  cursor: pointer;
  font-weight: 500;
}

.choice:hover {
  background: #f0f8f2;
}

.choice input {
  width: auto;
  margin-right: 8px;
  margin-bottom: 0;
}

.submit-area {
  text-align: center;
  padding: 28px 0 48px;
}

.warning {
  background: #fff3cd;
  color: #664d03;
  padding: 14px 18px;
  border-radius: 14px;
  margin-bottom: 20px;
  font-weight: 700;
}

.note {
  color: #5b6f63;
}

@media (max-width: 640px) {
  #app {
    padding: 12px;
  }

  .card {
    padding: 22px;
  }

  .exam-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .timer {
    width: 100%;
    text-align: center;
  }
}