:root {
  color-scheme: light;
  --page-bg:
    radial-gradient(circle at top, rgba(126, 92, 255, 0.18), transparent 36%),
    linear-gradient(180deg, #f5f7ff 0%, #eef2ff 44%, #f8f6ff 100%);
  --surface: rgba(255, 255, 255, 0.76);
  --surface-strong: rgba(255, 255, 255, 0.92);
  --surface-border: rgba(99, 102, 241, 0.14);
  --text-main: #111827;
  --text-subtle: #5b6474;
  --accent: #5b5bd6;
  --accent-strong: #4747bf;
  --accent-soft: rgba(91, 91, 214, 0.12);
  --shadow-lg: 0 24px 64px rgba(38, 45, 86, 0.12);
  --shadow-sm: 0 10px 24px rgba(20, 25, 48, 0.08);
  --pill-bg: rgba(255, 255, 255, 0.66);
  --pill-border: rgba(91, 91, 214, 0.14);
  --theme-toggle-bg: rgba(255, 255, 255, 0.78);
  --theme-toggle-border: rgba(91, 91, 214, 0.16);
  --theme-button-bg: transparent;
  --theme-button-text: #5b6474;
  --theme-button-active-bg: rgba(91, 91, 214, 0.16);
  --theme-button-active-text: #4747bf;
  --mode-button-bg: #f4f6ff;
  --mode-button-text: #5b6474;
  --button-neutral-bg: #ffffff;
  --button-neutral-border: rgba(91, 91, 214, 0.14);
  --input-bg: #ffffff;
  --input-border: rgba(91, 91, 214, 0.16);
  --textarea-bg: rgba(255, 255, 255, 0.92);
  --icon-button-bg: rgba(255, 255, 255, 0.92);
  --icon-button-border: rgba(91, 91, 214, 0.14);
  --focus-ring: rgba(91, 91, 214, 0.16);
  --focus-border: rgba(91, 91, 214, 0.32);
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --mono-font:
    "BIZ UD Gothic", "Noto Sans Mono CJK JP", "SFMono-Regular", "Consolas",
    "Liberation Mono", monospace;
  --ui-font:
    "Inter", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", "Meiryo",
    system-ui, sans-serif;
}

:root[data-theme="light"] {
  color-scheme: light;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --page-bg:
    radial-gradient(circle at top, rgba(124, 92, 255, 0.24), transparent 32%),
    linear-gradient(180deg, #0b1020 0%, #11182e 48%, #0d1226 100%);
  --surface: rgba(12, 18, 36, 0.78);
  --surface-strong: rgba(18, 26, 48, 0.92);
  --surface-border: rgba(148, 163, 184, 0.16);
  --text-main: #e5ecff;
  --text-subtle: #a9b5d1;
  --accent: #a78bfa;
  --accent-strong: #d9ceff;
  --accent-soft: rgba(167, 139, 250, 0.18);
  --shadow-lg: 0 24px 64px rgba(2, 6, 23, 0.45);
  --shadow-sm: 0 12px 28px rgba(2, 6, 23, 0.32);
  --pill-bg: rgba(15, 23, 42, 0.56);
  --pill-border: rgba(167, 139, 250, 0.18);
  --theme-toggle-bg: rgba(15, 23, 42, 0.78);
  --theme-toggle-border: rgba(167, 139, 250, 0.18);
  --theme-button-bg: transparent;
  --theme-button-text: #c8d3ed;
  --theme-button-active-bg: rgba(167, 139, 250, 0.22);
  --theme-button-active-text: #f3efff;
  --mode-button-bg: rgba(15, 23, 42, 0.88);
  --mode-button-text: #c8d3ed;
  --button-neutral-bg: rgba(15, 23, 42, 0.92);
  --button-neutral-border: rgba(148, 163, 184, 0.18);
  --input-bg: rgba(8, 14, 29, 0.92);
  --input-border: rgba(148, 163, 184, 0.18);
  --textarea-bg: rgba(8, 14, 29, 0.92);
  --icon-button-bg: rgba(15, 23, 42, 0.92);
  --icon-button-border: rgba(148, 163, 184, 0.18);
  --focus-ring: rgba(167, 139, 250, 0.22);
  --focus-border: rgba(167, 139, 250, 0.34);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --page-bg:
      radial-gradient(circle at top, rgba(124, 92, 255, 0.24), transparent 32%),
      linear-gradient(180deg, #0b1020 0%, #11182e 48%, #0d1226 100%);
    --surface: rgba(12, 18, 36, 0.78);
    --surface-strong: rgba(18, 26, 48, 0.92);
    --surface-border: rgba(148, 163, 184, 0.16);
    --text-main: #e5ecff;
    --text-subtle: #a9b5d1;
    --accent: #a78bfa;
    --accent-strong: #d9ceff;
    --accent-soft: rgba(167, 139, 250, 0.18);
    --shadow-lg: 0 24px 64px rgba(2, 6, 23, 0.45);
    --shadow-sm: 0 12px 28px rgba(2, 6, 23, 0.32);
    --pill-bg: rgba(15, 23, 42, 0.56);
    --pill-border: rgba(167, 139, 250, 0.18);
    --theme-toggle-bg: rgba(15, 23, 42, 0.78);
    --theme-toggle-border: rgba(167, 139, 250, 0.18);
    --theme-button-bg: transparent;
    --theme-button-text: #c8d3ed;
    --theme-button-active-bg: rgba(167, 139, 250, 0.22);
    --theme-button-active-text: #f3efff;
    --mode-button-bg: rgba(15, 23, 42, 0.88);
    --mode-button-text: #c8d3ed;
    --button-neutral-bg: rgba(15, 23, 42, 0.92);
    --button-neutral-border: rgba(148, 163, 184, 0.18);
    --input-bg: rgba(8, 14, 29, 0.92);
    --input-border: rgba(148, 163, 184, 0.18);
    --textarea-bg: rgba(8, 14, 29, 0.92);
    --icon-button-bg: rgba(15, 23, 42, 0.92);
    --icon-button-border: rgba(148, 163, 184, 0.18);
    --focus-ring: rgba(167, 139, 250, 0.22);
    --focus-border: rgba(167, 139, 250, 0.34);
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  background: var(--page-bg);
  color: var(--text-main);
  font-family: var(--ui-font);
  transition:
    background 0.25s ease,
    color 0.25s ease;
}

button,
input,
textarea {
  font: inherit;
}

.page-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  padding: 56px 0 72px;
}

.hero {
  margin-bottom: 28px;
}

.hero-topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 10px;
}

.eyebrow,
.panel-kicker {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.75rem);
  line-height: 1.04;
  letter-spacing: -0.04em;
}

.hero-copy {
  width: min(720px, 100%);
  margin: 16px 0 0;
  color: var(--text-subtle);
  font-size: 1.05rem;
  line-height: 1.7;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.hero-meta span {
  padding: 10px 14px;
  border: 1px solid var(--pill-border);
  border-radius: 999px;
  background: var(--pill-bg);
  color: var(--text-subtle);
  font-size: 0.95rem;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px;
  border: 1px solid var(--theme-toggle-border);
  border-radius: 999px;
  background: var(--theme-toggle-bg);
  box-shadow: var(--shadow-sm);
}

.theme-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  cursor: pointer;
  border: none;
  border-radius: 999px;
  background: var(--theme-button-bg);
  color: var(--theme-button-text);
  transition:
    transform 0.18s ease,
    background-color 0.18s ease,
    color 0.18s ease,
    box-shadow 0.18s ease;
}

.theme-button:hover {
  transform: translateY(-1px);
}

.theme-button.is-active {
  background: var(--theme-button-active-bg);
  color: var(--theme-button-active-text);
  box-shadow: var(--shadow-sm);
}

.theme-icon {
  display: block;
}

.layout {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  grid-template-areas:
    "controls controls"
    "status status"
    "input output";
}

.panel {
  border: 1px solid var(--surface-border);
  border-radius: var(--radius-xl);
  background: var(--surface);
  box-shadow: var(--shadow-lg);
  backdrop-filter: blur(18px);
}

.controls-panel {
  grid-area: controls;
  padding: 26px;
}

.status-panel {
  grid-area: status;
  padding: 22px 26px;
}

.editor-panel {
  padding: 22px;
}

.editor-panel:first-of-type {
  grid-area: input;
}

.editor-panel:last-of-type {
  grid-area: output;
}

.panel-heading {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: flex-start;
  margin-bottom: 18px;
}

.compact-heading {
  margin-bottom: 14px;
}

.panel-heading h2 {
  margin: 0;
  font-size: 1.3rem;
}

.output-panel-heading {
  align-items: center;
}

.panel-description {
  max-width: 28rem;
  margin: 0;
  color: var(--text-subtle);
  line-height: 1.6;
}

.controls-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 18px;
}

.control-block {
  padding: 18px;
  border-radius: var(--radius-lg);
  background: var(--surface-strong);
  box-shadow: var(--shadow-sm);
}

.control-label {
  display: inline-block;
  margin-bottom: 12px;
  font-size: 0.95rem;
  font-weight: 700;
}

.segmented-control {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.segmented-control--two {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.mode-button,
.secondary-button,
.primary-button {
  cursor: pointer;
  border: 1px solid transparent;
  border-radius: 14px;
  padding: 12px 14px;
  font-weight: 700;
  transition:
    transform 0.18s ease,
    background-color 0.18s ease,
    border-color 0.18s ease,
    box-shadow 0.18s ease;
}

.mode-button {
  background: var(--mode-button-bg);
  color: var(--mode-button-text);
}

.mode-button:hover,
.secondary-button:hover,
.primary-button:hover {
  transform: translateY(-1px);
}

.mode-button.is-active {
  border-color: rgba(91, 91, 214, 0.25);
  background: linear-gradient(180deg, rgba(91, 91, 214, 0.18), rgba(91, 91, 214, 0.1));
  color: var(--accent-strong);
  box-shadow: 0 12px 28px rgba(91, 91, 214, 0.12);
}

.filler-input-wrap {
  display: flex;
  align-items: center;
  gap: 12px;
}

#filler-input {
  width: 100%;
  min-width: 0;
  border: 1px solid var(--input-border);
  border-radius: 14px;
  padding: 12px 14px;
  background: var(--input-bg);
  color: var(--text-main);
}

.theme-button:focus-visible,
.mode-button:focus-visible,
.secondary-button:focus-visible,
.primary-button:focus-visible,
.icon-button:focus-visible,
#filler-input:focus,
textarea:focus {
  outline: 3px solid var(--focus-ring);
  border-color: var(--focus-border);
}

.filler-preview {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 46px;
  height: 46px;
  border-radius: 14px;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-weight: 700;
  font-size: 1.25rem;
}

.actions-block {
  display: flex;
  flex-direction: column;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.secondary-button {
  border-color: var(--button-neutral-border);
  background: var(--button-neutral-bg);
  color: var(--text-main);
}

.primary-button {
  background: linear-gradient(180deg, #5b5bd6 0%, #4444b8 100%);
  color: #fff;
  box-shadow: 0 16px 34px rgba(69, 69, 184, 0.24);
}

.primary-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
  transform: none;
}

.icon-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 46px;
  height: 46px;
  flex-shrink: 0;
  cursor: pointer;
  border: 1px solid var(--icon-button-border);
  border-radius: 14px;
  background: var(--icon-button-bg);
  color: var(--accent-strong);
  box-shadow: var(--shadow-sm);
  transition:
    transform 0.18s ease,
    background-color 0.18s ease,
    border-color 0.18s ease,
    box-shadow 0.18s ease,
    opacity 0.18s ease;
}

.icon-button:hover {
  transform: translateY(-1px);
  border-color: var(--focus-border);
  background: var(--button-neutral-bg);
}

.icon-button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
  transform: none;
  box-shadow: none;
}

.icon-copy {
  display: block;
}

.status-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  margin: 0;
}

.status-item {
  padding: 16px;
  border-radius: var(--radius-lg);
  background: var(--surface-strong);
}

.status-item dt {
  margin-bottom: 8px;
  color: var(--text-subtle);
  font-size: 0.9rem;
}

.status-item dd {
  margin: 0;
  font-size: 1rem;
  font-weight: 700;
}

.helper-text {
  margin: 10px 0 0;
  color: var(--text-subtle);
  font-size: 0.92rem;
  line-height: 1.6;
}

textarea {
  width: 100%;
  min-height: 360px;
  resize: vertical;
  border: 1px solid var(--input-border);
  border-radius: 18px;
  padding: 18px;
  background: var(--textarea-bg);
  color: var(--text-main);
  line-height: 1.8;
  font-family: var(--mono-font);
  font-size: 1rem;
}

.live-region {
  min-height: 1.5em;
  margin: 12px 0 0;
  color: var(--accent-strong);
  font-size: 0.95rem;
  font-weight: 700;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
    grid-template-areas:
      "controls"
      "status"
      "input"
      "output";
  }

  .controls-grid,
  .status-grid {
    grid-template-columns: 1fr;
  }

  textarea {
    min-height: 280px;
  }
}

@media (max-width: 640px) {
  .page-shell {
    width: min(100% - 20px, 1180px);
    padding: 28px 0 40px;
  }

  .hero-topbar {
    align-items: flex-start;
  }

  .controls-panel,
  .status-panel,
  .editor-panel {
    padding: 18px;
  }

  .panel-heading {
    flex-direction: column;
  }

  .output-panel-heading {
    flex-direction: row;
    align-items: center;
  }

  .theme-toggle {
    align-self: flex-end;
  }

  .segmented-control {
    grid-template-columns: 1fr;
  }

  .action-row {
    flex-direction: column;
  }

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