/* Gas Fill Planner — sleek minimal shell, dark by default. */
:root {
  --bg: #0b0e13;
  --panel: #12161d;
  --panel-2: #171c25;
  --line: #232a35;
  --line-soft: #1b212b;
  --text: #e6eaf2;
  --muted: #8b97ab;
  --accent: #38bdf8;
  --accent-dim: #0e7490;
  --ok: #34d399;
  --warn: #fbbf24;
  --danger: #f87171;
  --shadow: 0 1px 2px rgba(0,0,0,.4), 0 8px 24px -12px rgba(0,0,0,.6);
  --r: 12px;
}
html[data-theme="light"] {
  --bg: #f6f7f9;
  --panel: #ffffff;
  --panel-2: #f2f4f7;
  --line: #e2e6ec;
  --line-soft: #edf0f4;
  --text: #131720;
  --muted: #5c6675;
  --accent: #0284c7;
  --accent-dim: #7dd3fc;
  --ok: #059669;
  --warn: #b45309;
  --danger: #dc2626;
  --shadow: 0 1px 2px rgba(16,24,40,.06), 0 10px 24px -16px rgba(16,24,40,.25);
}

* { box-sizing: border-box; }
html, body { margin: 0; }
body {
  background: var(--bg);
  color: var(--text);
  font: 14px/1.5 ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  padding-bottom: 3rem;
}
h1, h2, h3 { margin: 0; font-weight: 600; letter-spacing: -0.01em; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .92em; }

/* ---------- top bar ---------- */
.topbar {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  flex-wrap: wrap;
  max-width: 1180px; margin: 0 auto; padding: 22px 20px 6px;
}
.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark { width: 30px; height: 30px; fill: var(--accent); flex: none; }
.topbar h1 { font-size: 1.05rem; }
.tagline { margin: 1px 0 0; color: var(--muted); font-size: .8rem; }
.topbar-actions { display: flex; gap: 8px; }

button { font: inherit; cursor: pointer; }
.ghost, .add {
  background: var(--panel); color: var(--text);
  border: 1px solid var(--line); border-radius: 8px;
  padding: 6px 11px; font-size: .8rem;
  transition: border-color .15s, color .15s, background .15s;
}
.ghost:hover, .add:hover { border-color: var(--accent); color: var(--accent); }
.add { background: transparent; }

main { max-width: 1180px; margin: 0 auto; padding: 14px 20px 0; }

.card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--r);
  box-shadow: var(--shadow);
  padding: 16px;
  margin-bottom: 16px;
}
.card-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-bottom: 12px; }
.card-head h2 { font-size: .95rem; }
.hint { color: var(--muted); font-size: .78rem; text-align: right; }

/* ---------- method + switch ---------- */
.controls { display: flex; align-items: center; justify-content: space-between; gap: 18px; flex-wrap: wrap; }
.seg { display: flex; gap: 6px; background: var(--panel-2); border: 1px solid var(--line-soft); border-radius: 10px; padding: 4px; flex-wrap: wrap; }
.seg-btn {
  background: transparent; border: 1px solid transparent; border-radius: 8px;
  color: var(--muted); text-align: left; padding: 7px 12px; display: block;
  transition: background .15s, color .15s, border-color .15s;
}
.seg-btn:hover { color: var(--text); }
.seg-btn.is-active { background: var(--panel); border-color: var(--line); color: var(--text); }
.seg-btn.is-active .seg-title { color: var(--accent); }
.seg-title { display: block; font-size: .85rem; font-weight: 600; }
.seg-sub { display: block; font-size: .72rem; color: var(--muted); margin-top: 1px; }

.switch { display: inline-flex; align-items: center; gap: 9px; user-select: none; cursor: pointer; }
.switch input { position: absolute; opacity: 0; width: 0; height: 0; }
.switch-track {
  width: 38px; height: 21px; border-radius: 999px;
  background: var(--panel-2); border: 1px solid var(--line);
  display: inline-flex; align-items: center; padding: 2px;
  transition: background .18s, border-color .18s;
}
.switch-knob { width: 15px; height: 15px; border-radius: 50%; background: var(--muted); transition: transform .18s, background .18s; }
.switch input:checked + .switch-track { background: color-mix(in srgb, var(--danger) 26%, transparent); border-color: var(--danger); }
.switch input:checked + .switch-track .switch-knob { transform: translateX(17px); background: var(--danger); }
.switch input:focus-visible + .switch-track { outline: 2px solid var(--accent); outline-offset: 2px; }
.switch-label { font-size: .82rem; color: var(--muted); }
.switch input:checked ~ .switch-label { color: var(--danger); }

/* ---------- bottle editor rows ---------- */
.columns { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; align-items: start; }
.bottle-list { display: flex; flex-direction: column; gap: 10px; }
.brow {
  display: grid; grid-template-columns: 52px 1fr auto; gap: 12px;
  align-items: center;
  background: var(--panel-2); border: 1px solid var(--line-soft);
  border-radius: 10px; padding: 10px 12px;
}
.brow.is-invalid { border-color: var(--danger); }
.brow-fields { display: grid; gap: 8px; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.brow-name { grid-column: 1 / -1; }
.field { display: flex; flex-direction: column; gap: 3px; min-width: 0; }
.field > span { font-size: .68rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.combo { display: flex; }
input[type="text"], input[type="number"], select {
  font: inherit; color: var(--text); background: var(--panel);
  border: 1px solid var(--line); border-radius: 7px;
  padding: 6px 8px; min-width: 0; width: 100%;
  appearance: none;
}
input[type="number"] { font-variant-numeric: tabular-nums; }
.combo input { border-radius: 7px 0 0 7px; border-right: none; }
.combo select { border-radius: 0 7px 7px 0; width: auto; min-width: 62px; color: var(--muted); background: var(--panel-2); padding-right: 6px; }
input:focus, select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent) 22%, transparent); }
.combo input:focus { border-right: none; }
.brow-del {
  background: transparent; border: 1px solid transparent; color: var(--muted);
  border-radius: 7px; width: 26px; height: 26px; line-height: 1; font-size: 15px;
}
.brow-del:hover { color: var(--danger); border-color: var(--danger); }

/* ---------- bottle graphics ---------- */
.bottle { display: block; overflow: visible; }
.bottle .shell { fill: var(--panel); stroke: var(--line); stroke-width: 1.4; }
.bottle .valve { fill: var(--muted); }
.bottle .level { fill: var(--accent); opacity: .85; }
.bottle .level.warnlevel { fill: var(--warn); }
.bottle .level.dangerlevel { fill: var(--danger); }
.bottle .tick { stroke: var(--muted); stroke-width: 1; stroke-dasharray: 2 2; }
.bottle .tick.max { stroke: var(--danger); }
.bottle .tick.target { stroke: var(--accent); stroke-dasharray: 3 2; }
.bottle-cap { text-align: center; font-size: .66rem; color: var(--muted); font-variant-numeric: tabular-nums; margin-top: 2px; }

.bottle-strip { display: flex; flex-wrap: wrap; gap: 14px; }
.bottle-strip .unit { width: 78px; }
.bottle-strip .name { text-align: center; font-size: .72rem; color: var(--text); margin-bottom: 2px;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

/* ---------- plan ---------- */
.issues { display: flex; flex-direction: column; gap: 6px; margin-bottom: 12px; }
.issue { font-size: .8rem; border-radius: 8px; padding: 7px 10px; border: 1px solid; }
.issue.warn { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 45%, transparent); background: color-mix(in srgb, var(--warn) 10%, transparent); }
.issue.error { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 45%, transparent); background: color-mix(in srgb, var(--danger) 10%, transparent); }

.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(132px, 1fr)); gap: 10px; }
.stat { background: var(--panel-2); border: 1px solid var(--line-soft); border-radius: 10px; padding: 10px 12px; }
.stat-v { font-size: 1.35rem; font-weight: 600; font-variant-numeric: tabular-nums; letter-spacing: -0.02em; }
.stat-l { font-size: .7rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin-top: 2px; }
.stat.accent .stat-v { color: var(--accent); }

.compare { margin: 14px 0 2px; }
.cmp { width: 100%; border-collapse: collapse; font-size: .8rem; font-variant-numeric: tabular-nums; }
.cmp th, .cmp td { text-align: right; padding: 7px 10px; border-bottom: 1px solid var(--line-soft); }
.cmp thead th {
  font-weight: 500; font-size: .68rem; text-transform: uppercase; letter-spacing: .05em;
  color: var(--muted); border-bottom-color: var(--line); white-space: nowrap;
}
.cmp th[scope="row"] { text-align: left; font-weight: 600; white-space: nowrap; }
.cmp tbody tr.is-active { background: color-mix(in srgb, var(--accent) 8%, transparent); }
.cmp tbody tr.is-active th[scope="row"] { color: var(--accent); }
.cmp tbody tr:not(.is-active) { color: var(--muted); }
.cmp-now { font-size: .62rem; text-transform: uppercase; letter-spacing: .06em; font-weight: 500;
  border: 1px solid color-mix(in srgb, var(--accent) 45%, transparent); border-radius: 999px;
  padding: 1px 6px; margin-left: 4px; }
.cmp-note { font-size: .8rem; color: var(--muted); margin: 10px 0 0; }
.cmp-note b { color: var(--text); font-weight: 600; }

.timeline { list-style: none; margin: 14px 0 0; padding: 0; display: flex; flex-direction: column; gap: 8px; }
.fill {
  border: 1px solid var(--line-soft); border-radius: 10px; background: var(--panel-2);
  overflow: hidden;
}
.fill.short { border-color: color-mix(in srgb, var(--warn) 40%, transparent); }
.fill.unsafe { border-color: color-mix(in srgb, var(--danger) 45%, transparent); }
.fill-head {
  display: flex; align-items: center; gap: 12px; padding: 9px 12px;
  border-bottom: 1px solid var(--line-soft); flex-wrap: wrap;
}
.fill-no { font-size: .7rem; color: var(--muted); font-variant-numeric: tabular-nums; min-width: 42px; }
.fill-title { font-size: .86rem; font-weight: 600; }
.fill-title .to { color: var(--accent); }
.fill-bar { flex: 1 1 120px; height: 6px; min-width: 90px; border-radius: 999px; background: var(--panel); overflow: hidden; position: relative; border: 1px solid var(--line-soft); }
.fill-bar i { position: absolute; inset: 0 auto 0 0; background: var(--accent); opacity: .35; }
.fill-bar b { position: absolute; inset: 0 auto 0 0; background: var(--accent); }
.tag { font-size: .68rem; padding: 2px 7px; border-radius: 999px; border: 1px solid var(--line); color: var(--muted); white-space: nowrap; }
.tag.full { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 45%, transparent); }
.tag.usable { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 45%, transparent); }
.tag.short { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 45%, transparent); }
.tag.danger { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 50%, transparent); background: color-mix(in srgb, var(--danger) 10%, transparent); }

.steps { list-style: none; margin: 0; padding: 4px 6px; display: flex; flex-direction: column; }
.step { display: grid; grid-template-columns: 20px minmax(0,1fr) 22px minmax(0,1fr) auto; gap: 8px; align-items: center;
  padding: 5px 6px; border-radius: 7px; font-size: .8rem; }
.step:hover { background: var(--panel); }
.step-n { color: var(--muted); font-size: .7rem; font-variant-numeric: tabular-nums; }
.step-arrow { color: var(--accent); text-align: center; }
.leg { display: flex; align-items: baseline; gap: 6px; min-width: 0; }
.leg .who { color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.leg .num { font-variant-numeric: tabular-nums; white-space: nowrap; }
.leg .num .after { font-weight: 600; }
.step .drop .after { color: var(--muted); }
.step .gain .after { color: var(--accent); }

.residual { margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--line-soft); }
.residual h3 { font-size: .78rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); margin-bottom: 10px; }
.empty { color: var(--muted); font-size: .85rem; padding: 6px 0; }

/* ---------- notes ---------- */
.notes h2 { font-size: .95rem; margin-bottom: 10px; }
.notes ul { margin: 0; padding-left: 18px; color: var(--muted); font-size: .82rem; }
.notes li { margin-bottom: 6px; }
.notes strong { color: var(--text); font-weight: 600; }
.disclaimer { color: var(--muted); font-size: .76rem; margin: 12px 0 0; padding-top: 10px; border-top: 1px solid var(--line-soft); }
footer { max-width: 1180px; margin: 0 auto; padding: 0 20px; color: var(--muted); font-size: .74rem; }

@media (max-width: 900px) {
  .columns { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .brow { grid-template-columns: 44px 1fr auto; padding: 9px; gap: 9px; }
  .brow-fields { grid-template-columns: 1fr; }
  .step { grid-template-columns: 1fr; gap: 2px; }
  .step-arrow { display: none; }
  .controls { align-items: flex-start; }
  .seg { width: 100%; }
  .seg-btn { flex: 1 1 140px; }
}

.fill-bar u { position: absolute; top: -2px; bottom: -2px; width: 0; border-left: 1px dashed var(--muted); text-decoration: none; }
.stat.small .stat-v { font-size: .95rem; padding: .25rem 0; }

@media (max-width: 620px) {
  /* The comparison table keeps its columns; it scrolls rather than squashing. */
  .compare { overflow-x: auto; }
  .cmp { min-width: 460px; }
}