:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-soft: #f8fafc;
  --text: #172033;
  --muted: #667085;
  --border: #d8e0ea;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-soft: #eaf1ff;
  --danger: #c62828;
  --danger-soft: #fff0f0;
  --success: #176b3a;
  --focus: rgba(37, 99, 235, 0.24);
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --radius: 16px;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-width: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.7;
  transition: background-color 0.2s ease, color 0.2s ease;
}

body.dark {
  --bg: #0f172a;
  --surface: #172033;
  --surface-soft: #111a2c;
  --text: #f3f6fb;
  --muted: #aeb9ca;
  --border: #344258;
  --primary: #6ea8ff;
  --primary-hover: #8bb9ff;
  --primary-soft: #20385f;
  --danger: #ff9a9a;
  --danger-soft: #3b1f24;
  --success: #9de1b4;
  --focus: rgba(110, 168, 255, 0.28);
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.24);
}

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

.site-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.header-inner,
.page-shell,
.site-footer {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
}

.header-inner {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  padding: 28px 0 24px;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--primary);
  font-size: 0.86rem;
  font-weight: 700;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  line-height: 1.25;
}

.lead {
  max-width: 760px;
  margin: 10px 0 0;
  color: var(--muted);
}

.theme-toggle,
.primary-button,
.secondary-button,
.ghost-button {
  min-height: 44px;
  border-radius: 10px;
  border: 1px solid transparent;
  padding: 10px 16px;
  font-weight: 700;
  transition: background-color 0.16s ease, border-color 0.16s ease, transform 0.08s ease;
}

.theme-toggle:active,
.primary-button:active,
.secondary-button:active,
.ghost-button:active {
  transform: translateY(1px);
}

.theme-toggle {
  flex: 0 0 auto;
  background: var(--surface-soft);
  color: var(--text);
  border-color: var(--border);
}

.theme-toggle:hover {
  background: var(--primary-soft);
}

.page-shell {
  padding: 28px 0 56px;
}

.tool-grid {
  display: grid;
  grid-template-columns: minmax(300px, 0.9fr) minmax(0, 1.4fr);
  gap: 24px;
  align-items: start;
}

.panel,
.content-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.panel {
  padding: 22px;
}

.panel-heading,
.result-topbar {
  margin-bottom: 18px;
}

.panel-heading h2,
.result-topbar h2,
.content-section h2 {
  margin: 0;
  line-height: 1.35;
}

.panel-heading p,
.result-count {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 0.92rem;
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.field-group {
  min-width: 0;
}

.field-group-full {
  grid-column: 1 / -1;
}

.field-group label,
.field-label {
  display: block;
  margin-bottom: 6px;
  font-weight: 700;
  font-size: 0.94rem;
}

.required {
  margin-left: 4px;
  color: var(--danger);
  font-size: 0.75rem;
}

input[type="text"],
select {
  width: 100%;
  min-width: 0;
  min-height: 44px;
  border: 1px solid var(--border);
  border-radius: 9px;
  background: var(--surface-soft);
  color: var(--text);
  padding: 10px 12px;
  outline: none;
  transition: border-color 0.16s ease, box-shadow 0.16s ease, background-color 0.16s ease;
}

input[type="text"]:focus,
select:focus,
button:focus-visible,
summary:focus-visible {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--focus);
  outline: none;
}

input[aria-invalid="true"] {
  border-color: var(--danger);
  background: var(--danger-soft);
}

input:disabled {
  opacity: 0.58;
  cursor: not-allowed;
}

.field-help,
.field-error {
  margin: 5px 0 0;
  font-size: 0.8rem;
  line-height: 1.45;
}

.field-help {
  color: var(--muted);
}

.field-error {
  min-height: 1.2em;
  color: var(--danger);
  font-weight: 600;
}

.zero-pad-group {
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
}

.switch-row {
  display: inline-flex !important;
  align-items: center;
  gap: 10px;
  width: fit-content;
  min-height: 44px;
  margin: 0 !important;
  cursor: pointer;
  user-select: none;
}

.switch-row input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.switch {
  position: relative;
  width: 48px;
  height: 26px;
  border-radius: 999px;
  background: var(--border);
  transition: background-color 0.18s ease;
}

.switch::after {
  content: "";
  position: absolute;
  top: 3px;
  left: 3px;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: #ffffff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.25);
  transition: transform 0.18s ease;
}

.switch-row input:checked + .switch {
  background: var(--primary);
}

.switch-row input:checked + .switch::after {
  transform: translateX(22px);
}

.switch-row input:focus-visible + .switch {
  box-shadow: 0 0 0 3px var(--focus);
}

.result-panel {
  min-width: 0;
}

.result-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.primary-button {
  flex: 0 0 auto;
  min-width: 128px;
  background: var(--primary);
  color: #ffffff;
}

body.dark .primary-button {
  color: #0f172a;
}

.primary-button:hover {
  background: var(--primary-hover);
}

.global-error {
  display: none;
  margin: 0 0 14px;
  padding: 10px 12px;
  border: 1px solid var(--danger);
  border-radius: 9px;
  background: var(--danger-soft);
  color: var(--danger);
  font-weight: 700;
}

.global-error.is-visible {
  display: block;
}

.result-output {
  width: 100%;
  min-height: 360px;
  margin: 0;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-soft);
  color: var(--text);
  padding: 16px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.95rem;
  line-height: 1.65;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.result-output:empty::before {
  content: attr(data-placeholder);
  color: var(--muted);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
}

.result-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 14px;
}

.secondary-button {
  background: var(--primary-soft);
  color: var(--primary);
  border-color: var(--primary);
}

.secondary-button:hover {
  filter: brightness(0.98);
}

.ghost-button {
  background: var(--surface-soft);
  color: var(--text);
  border-color: var(--border);
}

.ghost-button:hover {
  border-color: var(--primary);
}

.copy-status {
  min-height: 1.5em;
  color: var(--success);
  font-weight: 700;
  font-size: 0.9rem;
}

.copy-status.is-error {
  color: var(--danger);
}

.content-section {
  margin-top: 28px;
  padding: 26px;
}

.content-section > p {
  margin: 10px 0 0;
  color: var(--muted);
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 22px;
}

.info-grid article {
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface-soft);
  padding: 16px;
}

.info-grid h3 {
  margin: 0;
  font-size: 1rem;
}

.info-grid p {
  margin: 7px 0 0;
  color: var(--muted);
  font-size: 0.93rem;
}

.faq-section details {
  border-top: 1px solid var(--border);
  padding: 14px 0;
}

.faq-section details:first-of-type {
  margin-top: 16px;
}

.faq-section summary {
  cursor: pointer;
  font-weight: 700;
}

.faq-section details p {
  margin: 9px 0 0;
  color: var(--muted);
}

.site-footer {
  padding: 0 0 28px;
  color: var(--muted);
  text-align: center;
  font-size: 0.86rem;
}

@media (max-width: 820px) {
  .header-inner {
    align-items: stretch;
  }

  .tool-grid {
    grid-template-columns: 1fr;
  }

  .result-panel {
    display: flex;
    flex-direction: column;
  }

  .result-topbar {
    align-items: stretch;
    flex-direction: column;
  }

  .primary-button {
    width: 100%;
  }

  .result-output {
    min-height: 260px;
  }

  .result-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .copy-status {
    grid-column: 1 / -1;
  }
}

@media (max-width: 600px) {
  .header-inner,
  .page-shell,
  .site-footer {
    width: min(100% - 22px, 1180px);
  }

  .header-inner {
    flex-direction: column;
    gap: 16px;
    padding: 22px 0 20px;
  }

  .theme-toggle {
    width: 100%;
  }

  .page-shell {
    padding-top: 18px;
  }

  .panel,
  .content-section {
    padding: 18px;
    border-radius: 13px;
  }

  .form-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .field-group-full {
    grid-column: auto;
  }

  .result-actions {
    grid-template-columns: 1fr;
  }

  .copy-status {
    grid-column: auto;
  }

  .secondary-button,
  .ghost-button {
    width: 100%;
  }

  .info-grid {
    grid-template-columns: 1fr;
  }

  .result-output {
    min-height: 220px;
    padding: 14px;
    font-size: 0.9rem;
  }
}