:root{
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0,0,0,.08);

  --bg: #f3f4f6;        /* fond clair gris */
  --panel: #ffffff;
  --text: #111827;      /* très lisible */
  --muted: #4b5563;
  --border: rgba(17,24,39,.12);

  --accent: #2563eb;
  --accent2: #7c3aed;

  --btnText: #ffffff;
  --dangerBg: rgba(220, 38, 38, .12);
  --dangerText: #b91c1c;

  --inputBg: #f8fafc;
  --focus: rgba(37, 99, 235, .28);

  --gridGap: 14px;
}

html[data-theme="dark"]{
  --bg: #0b1220;
  --panel: #0f172a;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --border: rgba(229,231,235,.14);

  --accent: #60a5fa;
  --accent2: #c4b5fd;

  --shadow: 0 18px 40px rgba(0,0,0,.35);

  --dangerBg: rgba(239, 68, 68, .18);
  --dangerText: #f87171;

  --inputBg: rgba(255,255,255,.06);
  --focus: rgba(96, 165, 250, .28);
}

*{ box-sizing: border-box; }
body{
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
  background: var(--bg);
  color: var(--text);
}

.topbar{
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 18px 18px 10px;
  max-width: 1050px;
  margin: 0 auto;
}

.logo{
  width: 70px;
  height: auto;
  border-radius: 90px;
  display: grid;
  place-items: center;
  display: block;
}

.wrap{
  max-width: 1050px;
  margin: 0 auto;
  padding: 10px 18px 28px;
  display: grid;
  grid-template-columns: 1.2fr .8fr;
  gap: var(--gridGap);
}

@media (max-width: 900px){
  .wrap{ grid-template-columns: 1fr; }
  .topbar{ flex-direction: column; align-items: flex-start; }
}

.card{
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
}

.card-small{ padding: 16px; }

h2{
  margin: 0 0 14px;
  font-size: 18px;
  letter-spacing: .2px;
}

.form{ display: flex; flex-direction: column; gap: 14px; }

.field{
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.field label{
  color: var(--muted);
  font-size: 13px;
}

.input{
  background: var(--inputBg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 12px;
  font-size: 16px;
  outline: none;
}

.input:focus{
  border-color: rgba(37, 99, 235, .55);
  box-shadow: 0 0 0 4px var(--focus);
}

.row{
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

@media (max-width: 520px){
  .row{ grid-template-columns: 1fr; }
}

.small .input{ width: 100%; }

.checkbox{
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  cursor: pointer;
  user-select: none;
}

.checkbox input{ width: 18px; height: 18px; }

.actions{
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.btn{
  appearance: none;
  border: 1px solid transparent;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  color: var(--btnText);
  padding: 11px 14px;
  border-radius: 12px;
  font-weight: 700;
  cursor: pointer;
}

.btn:hover{ filter: brightness(1.03); }
.btn:active{ transform: translateY(1px); }

.btn-ghost{
  background: transparent;
  border-color: var(--border);
  color: var(--text);
  font-weight: 650;
}

.btn-ghost:hover{
  border-color: rgba(127,127,127,.35);
  background: rgba(127,127,127,.08);
}

.select{
  background: var(--inputBg);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 10px 12px;
  font-size: 15px;
}

.results{
  margin-top: 6px;
  padding: 14px;
  border: 1px dashed rgba(127,127,127,.25);
  border-radius: 12px;
}

.resultLine{
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding: 6px 0;
}

.resultLine.big{
  padding-top: 10px;
}

.label{
  color: var(--muted);
  font-size: 13px;
}

.value{
  font-size: 16px;
  font-weight: 800;
  text-align: right;
}

.resultLine.big .value{
  font-size: 22px;
}

.dir{
  margin-right: 8px;
  font-weight: 900;
}

.hint{
  color: var(--muted);
  font-size: 13px;
  margin-top: 8px;
  line-height: 1.35;
}

.error{
  margin-top: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  background: var(--dangerBg);
  color: var(--dangerText);
  border: 1px solid rgba(239, 68, 68, .35);
  font-size: 13px;
}

.muted{ color: var(--muted); margin: 0 0 12px; font-size: 13px; }

.history{
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.histItem{
  border: 1px solid var(--border);
  background: rgba(127,127,127,.06);
  border-radius: 12px;
  padding: 10px 12px;
}

.histTop{
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 6px;
}

.histFormula{
  font-weight: 800;
  font-size: 13px;
}
.histWhen{
  color: var(--muted);
  font-size: 12px;
  white-space: nowrap;
}

.histMeta{
  display: flex;
  justify-content: space-between;
  gap: 10px;
  color: var(--muted);
  font-size: 13px;
}