:root {
  --bg: #eef0f4;
  --card: #ffffff;
  --ink: #23262b;
  --ink-soft: #5b6270;
  --line: #d7dbe2;
  --accent: #3161d4;
  --accent-ink: #ffffff;
  --danger: #c0392b;
  --danger-bg: #fdecea;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20, 24, 33, .06), 0 8px 24px rgba(20, 24, 33, .07);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #191c21;
    --card: #22262d;
    --ink: #e8eaee;
    --ink-soft: #9aa1ad;
    --line: #363c46;
    --danger-bg: #3a1f1c;
    --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 8px 24px rgba(0, 0, 0, .35);
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: ui-sans-serif, -apple-system, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--ink);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header { text-align: center; padding: 34px 16px 10px; }
.wordmark { display: flex; align-items: center; justify-content: center; gap: 12px; }
.logo-atom { width: 40px; height: 40px; }
h1 { margin: 0; font-size: 2rem; letter-spacing: .14em; }
.tagline { color: var(--ink-soft); margin: 8px 0 0; }
.tagline code { background: var(--card); border: 1px solid var(--line);
  border-radius: 5px; padding: 1px 5px; }

main { flex: 1; width: min(1080px, 94vw); margin: 22px auto 40px; }

/* ---------- upload ---------- */
#drop-card { max-width: 640px; margin: 0 auto; }
#dropzone {
  background: var(--card);
  border: 2px dashed var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 44px 24px;
  text-align: center;
  cursor: pointer;
  transition: border-color .15s, transform .15s;
}
#dropzone:hover, #dropzone:focus-visible, #dropzone.dragover {
  border-color: var(--accent);
  outline: none;
}
#dropzone.dragover { transform: scale(1.015); }
#dropzone.busy { pointer-events: none; opacity: .75; }
#dropzone.busy .dz-busy { display: block; }
.dz-art { display: flex; justify-content: center; align-items: flex-end;
  gap: 10px; margin-bottom: 18px; }
.dz-art img { animation: bob 2.6s ease-in-out infinite; }
.dz-art img:nth-child(2) { animation-delay: .4s; }
.dz-art img:nth-child(3) { animation-delay: .8s; }
.dz-art img:nth-child(4) { animation-delay: 1.2s; }
@keyframes bob { 0%,100% { transform: translateY(0) } 50% { transform: translateY(-7px) } }
.dz-main { font-size: 1.15rem; margin: 0 0 6px; }
.dz-sub { color: var(--ink-soft); margin: 0; }
.dz-busy { color: var(--accent); font-weight: 600; margin: 14px 0 0; }

.demo-row { display: flex; gap: 10px; align-items: center; justify-content: center;
  margin-top: 16px; color: var(--ink-soft); flex-wrap: wrap; }

#error-box {
  margin-top: 16px; padding: 12px 16px;
  background: var(--danger-bg); color: var(--danger);
  border: 1px solid color-mix(in srgb, var(--danger) 35%, transparent);
  border-radius: 10px; white-space: pre-wrap;
}

/* ---------- buttons ---------- */
.btn {
  font: inherit; font-size: .88rem;
  background: var(--accent); color: var(--accent-ink);
  border: 1px solid transparent; border-radius: 9px;
  padding: 7px 13px; cursor: pointer;
}
.btn:hover { filter: brightness(1.1); }
.btn.ghost {
  background: transparent; color: var(--accent);
  border-color: color-mix(in srgb, var(--accent) 45%, transparent);
}

/* ---------- result layout ---------- */
#result { display: grid; grid-template-columns: 1fr 320px; gap: 18px;
  align-items: start; }
#result[hidden] { display: none; }
@media (max-width: 880px) { #result { grid-template-columns: 1fr; } }

.viewer-card, .charges-card {
  background: var(--card); border-radius: var(--radius);
  box-shadow: var(--shadow); overflow: hidden;
}
.toolbar {
  display: flex; justify-content: space-between; align-items: center;
  gap: 10px; flex-wrap: wrap;
  padding: 12px 16px; border-bottom: 1px solid var(--line);
}
.mol-id { display: flex; align-items: baseline; gap: 10px; }
#mol-name { font-weight: 650; }
.formula { color: var(--ink-soft); }
.formula sub { font-size: .72em; }
.toolbar-actions { display: flex; gap: 8px; align-items: center; flex-wrap: wrap; }
.toggle { display: flex; gap: 5px; align-items: center; font-size: .88rem;
  color: var(--ink-soft); cursor: pointer; user-select: none; }
.tgl-group { display: flex; gap: 7px; align-items: center; font-size: .88rem;
  color: var(--ink); padding: 3px 8px; border: 1px solid var(--line);
  border-radius: 9px; }

#canvas-wrap { width: 100%; aspect-ratio: 4 / 3; touch-action: none; }
#canvas-wrap svg { display: block; width: 100%; height: 100%;
  cursor: grab; }
#canvas-wrap svg:active { cursor: grabbing; }
.hint { text-align: center; color: var(--ink-soft); font-size: .8rem;
  margin: 0; padding: 8px 0 12px; }

/* ---------- charges table ---------- */
#ml-note { margin: 0; padding: 10px 14px; font-size: .82rem;
  color: var(--ink-soft);
  background: color-mix(in srgb, #f5a623 12%, transparent);
  border-bottom: 1px solid var(--line); }
#ml-warning { margin: 0; padding: 10px 14px; font-size: .82rem;
  font-weight: 550; color: var(--danger);
  background: var(--danger-bg);
  border-bottom: 1px solid color-mix(in srgb, var(--danger) 35%, var(--line)); }
#ml-warning::before { content: "⚠ "; }
.totals { display: grid; grid-template-columns: repeat(4, 1fr);
  border-bottom: 1px solid var(--line); }
.totals > div { padding: 12px 8px; text-align: center; }
.totals .k { display: block; font-size: .72rem; text-transform: none;
  letter-spacing: .07em; color: var(--ink-soft); }
.totals .v { font-weight: 650; font-variant-numeric: tabular-nums; }

.table-scroll { max-height: 480px; overflow-y: auto; }
table { width: 100%; border-collapse: collapse; font-size: .9rem; }
th, td { padding: 6px 12px; text-align: left; }
thead th { position: sticky; top: 0; background: var(--card);
  color: var(--ink-soft); font-weight: 550; font-size: .78rem;
  border-bottom: 1px solid var(--line); }
tbody tr { cursor: default; }
tbody tr:hover { background: color-mix(in srgb, var(--accent) 9%, transparent); }
td.q { font-variant-numeric: tabular-nums; }
.el-dot { display: inline-block; width: 11px; height: 11px; border-radius: 50%;
  margin-right: 7px; vertical-align: -1px; border: 1.5px solid rgba(0,0,0,.45); }
.soon { color: var(--ink-soft); opacity: .55; }

footer { text-align: center; color: var(--ink-soft); font-size: .78rem;
  padding: 18px 16px 26px; }