:root {
  --bg: #ffffff;
  --surface: #ffffff;
  --border: #d0d4da;
  --text: #1f2329;
  --muted: #5b6470;
  --slate: #3d4d5c;
  --slate-dark: #2c3744;
  --green: #15b415;
  --accent: #dc2626;
  --radius: 8px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Yu Gothic", Meiryo, sans-serif;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--text); font-family: var(--font);
  font-size: 16px; line-height: 1.55; min-height: 100vh;
  display: flex; flex-direction: column;
  -webkit-text-size-adjust: 100%;
}

/* header */
.app-header { background: var(--slate); color: #fff; position: sticky; top: 0; z-index: 10; }
.app-header-inner {
  max-width: 900px; margin: 0 auto;
  padding: 12px 16px calc(12px + env(safe-area-inset-bottom, 0)) 16px;
  padding-top: calc(12px + env(safe-area-inset-top, 0));
  display: flex; align-items: center; gap: 10px;
}
.app-header h1 { margin: 0; font-size: 1.05rem; font-weight: 700; letter-spacing: 0.01em; }
.app-header .tag {
  margin-left: auto; font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.06em;
  background: rgba(255,255,255,0.15); padding: 3px 8px; border-radius: 999px;
}

/* layout */
.container { flex: 1; width: 100%; max-width: 900px; margin: 0 auto; padding: 16px; }
.muted { color: var(--muted); }

/* toolbar */
.toolbar { display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; }
.toolbar input[type="search"] { flex: 2 1 220px; }
.toolbar select { flex: 1 1 160px; }
input[type="search"], input[type="number"], select {
  width: 100%; padding: 9px 10px; font-size: 1rem; font-family: inherit;
  background: var(--surface); color: var(--text);
  border: 1px solid var(--border); border-radius: 6px;
}
input:focus, select:focus { outline: none; border-color: var(--slate); box-shadow: 0 0 0 2px rgba(61,77,92,0.18); }

/* calc list */
.calc-list { display: flex; flex-direction: column; }
.cat-head {
  margin: 18px 0 6px; font-size: 0.72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.06em; color: var(--muted); border-bottom: 1px solid var(--border); padding-bottom: 4px;
}
.calc-row {
  display: block; padding: 11px 12px; text-decoration: none; color: var(--text);
  border: 1px solid var(--border); border-radius: 6px; margin: 4px 0; background: var(--surface);
  transition: border-color .12s, transform .04s;
}
.calc-row:hover { border-color: var(--slate); }
.calc-row:active { transform: translateY(1px); }

/* detail */
.back { display: inline-block; margin: 4px 0 10px; color: var(--slate); text-decoration: none; font-weight: 600; }
.back:hover { text-decoration: underline; }
.cat-tag { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); }
.calc-title { margin: 2px 0 16px; font-size: 1.35rem; }
.calc-form { margin-bottom: 8px; }
.field { display: flex; flex-direction: column; gap: 5px; margin-bottom: 13px; }
.field label { font-weight: 600; font-size: 0.82rem; color: var(--slate-dark); }
.btn-row { display: flex; gap: 8px; margin-top: 6px; flex-wrap: wrap; }
.btn {
  padding: 10px 18px; font-size: 0.95rem; font-weight: 600; font-family: inherit;
  color: var(--text); background: #eef0f2; border: 1px solid var(--border);
  border-radius: 6px; cursor: pointer;
}
.btn:hover { background: #e2e6ea; }
.btn.primary { background: var(--slate); color: #fff; border-color: var(--slate); }
.btn.primary:hover { background: var(--slate-dark); }
.btn.small { padding: 6px 12px; font-size: 0.85rem; margin-top: 10px; }

/* result */
.result-box { margin-top: 18px; }
.result-head {
  display: flex; align-items: baseline; gap: 10px; flex-wrap: wrap;
  padding: 12px 14px; border-radius: 8px; background: #f3f6f4; border: 1px solid #cfe3d2;
}
.result-head.err { background: #fdf0f0; border-color: #f0c9c9; }
.result-label { font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.06em; color: var(--muted); }
.result-value { font-family: var(--mono); font-size: 1.5rem; font-weight: 700; color: var(--slate-dark); }
.result-head.err .result-value { color: var(--accent); font-size: 1.1rem; }
.result-body {
  margin: 10px 0 0; padding: 12px 14px; white-space: pre-wrap; word-break: break-word;
  font-family: var(--mono); font-size: 0.9rem; line-height: 1.5;
  background: var(--surface); border: 1px solid var(--border); border-radius: 8px; color: var(--text);
}

/* footer + fatal */
.app-footer {
  margin-top: auto; padding: 16px; text-align: center; font-size: 0.78rem; color: var(--muted);
  border-top: 1px solid var(--border);
}
.fatal { max-width: 640px; margin: 60px auto; padding: 24px; text-align: center; color: var(--muted); line-height: 1.7; }
.fatal code { background: #f0f0f0; padding: 1px 5px; border-radius: 4px; font-family: var(--mono); }

@media (max-width: 600px) {
  .calc-title { font-size: 1.2rem; }
  .btn { flex: 1 1 auto; }
}