:root {
  color-scheme: light dark;
  --accent: #1ab8db;
  --accent-ink: #0b7f99;
  --warm: #fa874a;
  --cool: #66d185;
  --error: #eb4038;
  --bg: #eef9ff;
  --bg2: #fff0e8;
  --card: #fffdf8;
  --row: #edf5fc;
  --border: #d4dee9;
  --ink: #1a1f24;
  --muted: #59616b;
  --shadow: 0 10px 28px rgba(0, 0, 0, 0.07);
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d141f;
    --bg2: #142638;
    --card: #17202b;
    --row: #1f333f;
    --border: #33475c;
    --ink: #ebf0f5;
    --muted: #9eadb8;
    --accent-ink: #5fd3ec;
    --shadow: 0 10px 28px rgba(0, 0, 0, 0.35);
  }
}

* { box-sizing: border-box; }

html { background: var(--bg); }

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Avenir Next", "Hiragino Sans", "Noto Sans JP", system-ui, sans-serif;
  color: var(--ink);
  background: linear-gradient(135deg, var(--bg), var(--bg2)) fixed;
  line-height: 1.6;
}

a { color: var(--accent-ink); }

.wrap { max-width: 980px; margin: 0 auto; padding: 20px 16px 64px; }

.site-top {
  display: flex; justify-content: space-between; align-items: center; gap: 12px;
  font-size: 0.9rem; color: var(--muted);
}
.site-top a { text-decoration: none; }
.lang a { margin-left: 10px; }
.lang a[aria-current="page"] { font-weight: 700; color: var(--ink); }

header.hero { margin: 18px 0 8px; }
h1 { font-size: clamp(1.6rem, 4vw, 2.3rem); line-height: 1.25; margin: 0 0 8px; }
.lede { color: var(--muted); margin: 0 0 14px; }

nav.tools {
  position: sticky; top: 0; z-index: 5;
  display: flex; gap: 6px; overflow-x: auto; padding: 10px 0;
  background: linear-gradient(var(--bg), color-mix(in srgb, var(--bg) 85%, transparent));
}
nav.tools a {
  flex: none; padding: 6px 12px; border-radius: 999px; border: 1px solid var(--border);
  background: var(--card); color: var(--ink); text-decoration: none; font-size: 0.9rem;
}
nav.tools a:hover { border-color: var(--accent); }

.grid { display: grid; gap: 16px; grid-template-columns: 1fr; }
@media (min-width: 860px) { .grid.two { grid-template-columns: 1fr 1fr; } }

section.card {
  background: var(--card); border: 1px solid var(--border); border-radius: 18px;
  box-shadow: var(--shadow); padding: 16px; scroll-margin-top: 64px; min-width: 0;
}
section.card > h2 { font-size: 1.15rem; margin: 0 0 12px; }
h3 { font-size: 1rem; margin: 16px 0 8px; }

.row {
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px 10px; padding: 8px 10px; margin: 6px 0;
  background: var(--row); border: 1px solid var(--border); border-radius: 12px; min-width: 0;
}
.row label, .chip {
  flex: none; font-size: 0.78rem; color: var(--muted); padding: 2px 8px; border-radius: 999px;
  background: var(--card); white-space: nowrap;
}
.row input, .row select, .row output, .row .val {
  flex: 1 1 auto; min-width: 0; font: 1rem var(--mono); color: var(--ink);
  background: transparent; border: 0; outline: none; overflow-wrap: break-word;
}
.row input { flex-basis: 6em; }
.row input[aria-label="BIN"] { font-size: 0.85rem; }
.row input[type="range"] { font: inherit; accent-color: var(--accent); }
.row output, .row .val { text-align: right; }
.row.input:focus-within { border-color: var(--accent); box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent) 30%, transparent); }
.row .err { color: var(--error); font-size: 0.8rem; }

button.copy {
  margin-left: auto;
  flex: none; border: 1px solid var(--border); background: var(--card); color: var(--accent-ink);
  border-radius: 999px; width: 30px; height: 30px; cursor: pointer; font-size: 0.85rem;
}
button.copy.done { background: var(--accent); color: #fff; }

.seg { display: flex; gap: 4px; padding: 3px; background: var(--row); border-radius: 10px; margin: 6px 0; flex-wrap: wrap; }
.seg button {
  flex: 1; border: 0; background: transparent; color: var(--ink); padding: 6px 8px;
  border-radius: 8px; cursor: pointer; font: inherit; font-size: 0.9rem;
}
.seg button[aria-pressed="true"] { background: var(--card); box-shadow: 0 1px 3px rgba(0,0,0,.12); font-weight: 600; }

button.primary, a.primary {
  display: inline-block; border: 0; background: var(--accent); color: #fff; padding: 9px 16px;
  border-radius: 12px; cursor: pointer; font: inherit; font-weight: 600; text-decoration: none;
}
button.ghost { border: 1px solid var(--border); background: var(--card); color: var(--ink); padding: 7px 12px; border-radius: 10px; cursor: pointer; font: inherit; }

details.work { margin-top: 10px; border: 1px solid var(--border); border-radius: 14px; padding: 10px 12px; background: var(--card); }
details.work summary { cursor: pointer; font-weight: 600; }
ol.steps { list-style: none; padding: 0; margin: 10px 0 0; counter-reset: step; }
ol.steps > li { counter-increment: step; position: relative; padding-left: 32px; margin: 10px 0; }
ol.steps > li::before {
  content: counter(step); position: absolute; left: 0; top: 1px; width: 22px; height: 22px; border-radius: 50%;
  background: var(--accent); color: #fff; font-size: 0.75rem; display: grid; place-items: center;
}
.formula, pre.lines {
  font: 0.92rem var(--mono); white-space: pre; overflow-x: auto; margin: 4px 0 0;
  background: var(--row); border-radius: 10px; padding: 8px 10px;
}
.formula { white-space: pre-wrap; overflow-wrap: anywhere; background: none; padding: 0; }
pre.lines .hl { color: var(--accent-ink); font-weight: 700; }

.bitgrid { display: grid; grid-template-columns: repeat(8, 1fr); gap: 5px; margin: 8px 0; }
.bitgrid button {
  border: 1px solid var(--border); border-radius: 8px; background: var(--row); color: var(--ink);
  padding: 3px 0; cursor: pointer; font: 0.95rem var(--mono); line-height: 1.1;
}
.bitgrid button small { display: block; font-size: 0.6rem; color: var(--muted); }
.bitgrid button.on { background: color-mix(in srgb, var(--accent) 40%, var(--row)); }

textarea {
  width: 100%; min-height: 90px; font: 0.95rem var(--mono); color: var(--ink); background: var(--row);
  border: 1px solid var(--border); border-radius: 12px; padding: 10px; resize: vertical;
}

table.sheet { width: 100%; border-collapse: collapse; font: 0.9rem var(--mono); }
table.sheet th { text-align: left; font: 0.75rem system-ui, sans-serif; color: var(--muted); border-bottom: 1px solid var(--border); padding: 6px; background: var(--card); }
table.sheet td { padding: 5px 6px; border-bottom: 1px solid color-mix(in srgb, var(--border) 50%, transparent); }
table.sheet tr.ctl td { color: var(--muted); }
table.sheet tr:hover td { background: var(--row); }
.table-scroll { overflow-x: auto; }

.promo {
  display: grid; gap: 12px; grid-template-columns: 1fr; align-items: center;
  background: linear-gradient(135deg, color-mix(in srgb, var(--accent) 18%, var(--card)), var(--card));
}
@media (min-width: 720px) { .promo { grid-template-columns: 1fr auto; } }
.promo ul { margin: 6px 0 0; padding-left: 1.2em; }
.store-badge {
  display: inline-flex; align-items: center; gap: 8px; background: #000; color: #fff; text-decoration: none;
  padding: 10px 16px; border-radius: 12px; font-weight: 600; white-space: nowrap;
}

.prose p, .prose li { color: var(--ink); }
.prose { max-width: 70ch; }
footer { margin-top: 32px; color: var(--muted); font-size: 0.85rem; }
.muted { color: var(--muted); font-size: 0.85rem; }