.page {
  flex: 1;
  max-width: 560px;
  width: 100%;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.tool {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ---------- Tabs ---------- */
.tabs {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.tab-btn {
  appearance: none;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--sub);
  font-family: "Noto Sans JP", sans-serif;
  font-size: 13px;
  font-weight: 500;
  padding: 7px 16px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 140ms ease, border-color 140ms ease, color 140ms ease;
  white-space: nowrap;
}

.tab-btn:hover {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent-deep);
}

.tab-btn[aria-selected="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
  font-weight: 700;
}

/* ---------- Mode panes ---------- */
.mode-pane {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.mode-pane[hidden] { display: none; }

/* ---------- Date inputs ---------- */
.date-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 8px;
  align-items: end;
}

.date-col {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.date-label {
  font-family: "JetBrains Mono", monospace;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

input[type="date"] {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: "Noto Sans JP", sans-serif;
  font-size: 14px;
  background: var(--surface);
  color: var(--ink);
  transition: border-color 140ms, box-shadow 140ms;
  box-sizing: border-box;
}

input[type="date"]:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

/* ---------- Swap button ---------- */
.swap-btn {
  appearance: none;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  width: 36px;
  height: 42px;
  font-size: 18px;
  color: var(--sub);
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: background 140ms, border-color 140ms, color 140ms;
  flex-shrink: 0;
}

.swap-btn:hover {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
}

/* ---------- Result area ---------- */
.result-area {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.result-row {
  display: flex;
  align-items: center;
  padding: 14px 18px;
  gap: 12px;
}

.result-row + .result-row { border-top: 1px solid var(--border); }

.result-row--accent { background: var(--accent-soft); }

.result-label {
  font-size: 12px;
  color: var(--muted);
  white-space: nowrap;
  min-width: 52px;
}

.result-val {
  flex: 1;
  font-family: "JetBrains Mono", monospace;
  font-size: 18px;
  font-weight: 600;
  color: var(--ink);
  text-align: right;
  letter-spacing: -0.01em;
}

.result-row--accent .result-val {
  color: var(--accent-deep);
  font-size: 17px;
}

.result-note {
  padding: 10px 18px;
  font-size: 12px;
  color: var(--muted);
  border-top: 1px solid var(--border);
  background: var(--bg);
}

/* ---------- Copy button ---------- */
.copy-btn {
  appearance: none;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--muted);
  padding: 4px;
  border-radius: 4px;
  display: grid;
  place-items: center;
  transition: color 120ms, background 120ms;
  flex-shrink: 0;
}

.copy-btn:hover { color: var(--accent); background: var(--accent-soft); }

/* ---------- Number stepper (mode B) ---------- */
.num-input-wrap {
  display: flex;
  align-items: center;
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--surface);
  transition: border-color 140ms, box-shadow 140ms;
}

.num-input-wrap:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.step-btn {
  appearance: none;
  background: var(--bg);
  border: none;
  width: 36px;
  height: 40px;
  font-size: 16px;
  color: var(--sub);
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: background 120ms, color 120ms;
  flex-shrink: 0;
}

.step-btn:hover { background: var(--accent-soft); color: var(--accent); }
.step-btn:first-child { border-right: 1px solid var(--border); }
.step-btn:last-child  { border-left:  1px solid var(--border); }

#numDays {
  flex: 1;
  border: none;
  padding: 10px 8px;
  font-family: "JetBrains Mono", monospace;
  font-size: 16px;
  font-weight: 500;
  text-align: center;
  background: transparent;
  color: var(--ink);
  -moz-appearance: textfield;
  min-width: 0;
}

#numDays:focus { outline: none; }
#numDays::-webkit-outer-spin-button,
#numDays::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }

/* ---------- Responsive ---------- */

@media (max-width: 480px) {
  .date-row         { grid-template-columns: 1fr; }
  .swap-btn         { justify-self: start; }
  .result-val       { font-size: 16px; }
}