:root{
  --bg:#f4f7fb;
  --card:#fff;
  --ink:#172033;
  --muted:#657086;
  --line:#dbe3ef;
  --accent:#2857c5;
  --soft:#eef3ff;
  --success:#16794b;
  --error:#9b2525
}

*{box-sizing:border-box}

.chemistry-tools-app{
  margin:0;
  font-family:Arial,Helvetica,sans-serif;
  background:var(--bg);
  color:var(--ink);
  line-height:1.45
}

.chemistry-tools-app .page{
  max-width:1050px;
  margin:auto;
  padding:30px 18px 50px
}

.chemistry-tools-app h1{
  margin:0 0 6px;
  font-size:clamp(28px,4vw,40px)
}

.subtitle{
  color:var(--muted);
  margin:0 0 22px
}

.card{
  background:var(--card);
  border:1px solid var(--line);
  border-radius:14px;
  padding:20px;
  box-shadow:0 4px 18px rgba(30,55,90,.05);
  margin-bottom:18px
}

.toolbar{
  display:flex;
  gap:14px;
  flex-wrap:wrap;
  align-items:end
}

.field{
  flex:1;
  min-width:180px
}

.chemistry-tools-app label{
  display:block;
  font-weight:700;
  margin-bottom:6px
}

.chemistry-tools-app select,
.chemistry-tools-app input{
  width:100%;
  padding:11px 12px;
  border:1px solid #bcc8da;
  border-radius:9px;
  font-size:16px;
  background:#fff
}

.chemistry-tools-app button{
  padding:12px 18px;
  border:0;
  border-radius:9px;
  background:var(--accent);
  color:#fff;
  font-size:16px;
  font-weight:700;
  cursor:pointer
}

.chemistry-tools-app button.secondary{
  background:#fff;
  color:var(--accent);
  border:1px solid var(--accent)
}

.chemistry-tools-app button:hover{
  filter:brightness(.96)
}

.question-name{
  text-align:center;
  font-family:"Cambria Math","Times New Roman",serif;
  font-size:clamp(26px,4vw,38px);
  font-weight:700;
  padding:12px 6px 4px
}

.builder-grid{
  display:grid;
  grid-template-columns:repeat(3,minmax(0,1fr));
  gap:14px
}

.sub-builder{
  display:grid;
  grid-template-columns:1fr 1fr auto;
  gap:10px;
  align-items:end
}

.preview{
  margin-top:18px;
  padding:14px;
  border:1px solid var(--line);
  border-radius:12px;
  background:#fbfcff;
  text-align:center;
  overflow:auto;
  min-height:230px
}

.chips{
  display:flex;
  gap:8px;
  flex-wrap:wrap;
  margin-top:12px
}

.chip{
  display:inline-flex;
  gap:7px;
  align-items:center;
  padding:7px 10px;
  border-radius:999px;
  background:var(--soft);
  border:1px solid #cfdafa;
  font-size:14px
}

.chip button{
  padding:0;
  border:0;
  background:transparent;
  color:var(--error);
  font-size:16px
}

.feedback{
  margin-top:14px;
  padding:13px;
  border-radius:9px;
  display:none
}

.feedback.good{
  display:block;
  background:#eefaf4;
  border:1px solid #ccebdc;
  color:var(--success)
}

.feedback.bad{
  display:block;
  background:#fff2f2;
  border:1px solid #efc7c7;
  color:var(--error)
}

.hint{
  color:var(--muted);
  font-size:13px;
  margin-top:6px
}

.score{
  font-weight:700;
  color:var(--muted)
}

@media(max-width:760px){
  .builder-grid{
    grid-template-columns:1fr
  }

  .sub-builder{
    grid-template-columns:1fr
  }
}