:root {
  --bg: #eef7f4;            /* เขียวมิ้นต์อ่อน */
  --bg-soft: #e3f1ec;
  --ink: #1f3b34;          /* เขียวเข้มหมึก */
  --ink-soft: #6a8a80;
  --teal: #1f9d8f;
  --teal-dark: #157a6e;
  --amber: #f2b441;
  --card: #ffffff;
  --shadow: 0 12px 32px rgba(21, 122, 110, 0.12);
  --radius: 20px;
  --good: #1f9d6b;
  --bad: #e25c5c;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: 'Sarabun', system-ui, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(1100px 480px at 85% -12%, #d6efe7 0%, transparent 60%),
    radial-gradient(820px 460px at -10% 18%, #fdeecb 0%, transparent 55%),
    var(--bg);
  line-height: 1.65;
}

h1, h2, h3, .logo { font-family: 'Mitr', 'Sarabun', sans-serif; font-weight: 600; }

.site-header {
  display: flex; align-items: center; justify-content: space-between;
  max-width: 920px; margin: 0 auto; padding: 22px 20px;
}
.logo { font-size: 1.2rem; color: var(--teal-dark); }
.nav a { color: var(--ink-soft); text-decoration: none; margin-left: 20px; font-weight: 600; }
.nav a:hover { color: var(--teal-dark); }

main { max-width: 760px; margin: 0 auto; padding: 0 20px 60px; }

.hero { text-align: center; padding: 18px 0 26px; }
.hero h1 { font-size: 2.2rem; margin: 0 0 12px; color: var(--ink); }
.hero .sub { font-size: 1.05rem; color: var(--ink-soft); max-width: 580px; margin: 0 auto; }

/* เครื่องมือ */
.tool-card {
  background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow);
  padding: 28px 26px; margin-bottom: 26px;
}
.field-label { display: block; font-weight: 700; margin: 0 0 10px; }
#contentInput {
  width: 100%; resize: vertical; font-family: inherit; font-size: 1rem;
  border: 1.5px solid #d6e7e1; border-radius: 14px; padding: 13px 15px;
  background: #fbfdfc; color: var(--ink);
}
#contentInput:focus { outline: none; border-color: var(--teal); }

.options { display: grid; grid-template-columns: 1fr 1fr; gap: 14px 18px; margin: 18px 0 22px; }
.opt-label { display: block; font-size: 0.82rem; font-weight: 700; color: var(--ink-soft); margin-bottom: 7px; }
.chips { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  border: 1.5px solid #d6e7e1; background: #fbfdfc; color: var(--ink-soft);
  padding: 7px 15px; border-radius: 999px; font-weight: 600; cursor: pointer;
  font-family: inherit; font-size: 0.9rem; transition: all .15s ease;
}
.chip:hover { border-color: var(--teal); color: var(--teal-dark); }
.chip.active { background: var(--teal); border-color: var(--teal); color: #fff; box-shadow: 0 5px 13px rgba(31,157,143,0.32); }

.btn {
  font-family: inherit; font-weight: 700; font-size: 1.05rem;
  border: none; border-radius: 14px; padding: 14px 30px; cursor: pointer;
  transition: transform .06s ease, box-shadow .2s ease, background .2s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary { width: 100%; background: var(--teal); color: #fff; box-shadow: 0 8px 18px rgba(31,157,143,0.38); }
.btn-primary:hover { background: var(--teal-dark); }
.btn-primary:disabled { opacity: .6; cursor: default; }
.btn-ghost { width: 100%; margin-top: 12px; background: var(--bg-soft); color: var(--teal-dark); }
.btn-ghost:hover { background: #d4ebe3; }

.status { margin-top: 16px; color: var(--ink-soft); font-weight: 600; text-align: center; }

.result { display: grid; gap: 14px; margin-top: 20px; }
.q-card {
  text-align: left; background: #fbfdfc; border: 1.5px solid #e0efe9;
  border-radius: 16px; padding: 16px 18px;
}
.q-head { display: flex; gap: 10px; align-items: baseline; }
.q-num { background: var(--teal); color: #fff; min-width: 26px; height: 26px; border-radius: 8px; display: grid; place-items: center; font-weight: 700; font-size: 0.9rem; flex-shrink: 0; }
.q-text { font-weight: 600; color: var(--ink); }
.choices { display: grid; gap: 8px; margin: 12px 0 0; }
.choice {
  text-align: left; border: 1.5px solid #e0efe9; background: #fff; color: var(--ink);
  border-radius: 10px; padding: 9px 13px; cursor: pointer; font-family: inherit; font-size: 0.98rem;
  transition: all .12s ease;
}
.choice:hover { border-color: var(--teal); }
.choice.selected { border-color: var(--teal); background: #eafaf6; }
.choice.correct { border-color: var(--good); background: #e6f7ee; color: #14663f; font-weight: 700; }
.choice.wrong { border-color: var(--bad); background: #fdeeee; color: #a23838; }
.q-actions { margin-top: 12px; }
.reveal {
  border: 1.5px solid var(--teal); background: transparent; color: var(--teal-dark);
  border-radius: 10px; padding: 6px 16px; font-weight: 700; cursor: pointer; font-family: inherit; font-size: 0.9rem;
}
.reveal:hover { background: var(--teal); color: #fff; }
.explain { margin-top: 10px; padding: 10px 13px; background: #fff8e6; border-radius: 10px; color: #7a5e1e; font-size: 0.95rem; }
.explain[hidden] { display: none; }

/* เนื้อหา */
.prose { background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow); padding: 26px 28px; margin-bottom: 22px; }
.prose h2 { margin-top: 0; }
.prose a { color: var(--teal-dark); }
.prose details { border-top: 1px solid #e6f1ed; padding: 12px 0; }
.prose summary { font-weight: 700; cursor: pointer; }
.prose details p { color: var(--ink-soft); margin: 8px 0 0; }

.site-footer { text-align: center; color: var(--ink-soft); padding: 30px 20px 50px; font-size: 0.9rem; }

@media (max-width: 560px) {
  .hero h1 { font-size: 1.8rem; }
  .options { grid-template-columns: 1fr; }
}