:root {
  --bg-primary: #fafafa;
  --bg-secondary: #ffffff;
  --bg-upload: #f5f5f5;
  --text-primary: #1a1a1a;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #eff6ff;
  --border: #e5e7eb;
  --border-hover: #cbd5e1;
  --border-focus: #2563eb;
  --success: #16a34a;
  --error: #dc2626;
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  color-scheme: light;
}

body {
  margin: 0;
  background: var(--bg-primary);
  color: var(--text-primary);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

a {
  color: inherit;
  text-decoration: none;
}

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

button,
input,
select {
  font: inherit;
}

button {
  cursor: pointer;
}

svg {
  display: block;
  width: 20px;
  height: 20px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 2;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  max-width: 1040px;
  margin: 0 auto;
  padding: 18px 24px;
  border-bottom: 1px solid var(--border);
}

.logo {
  flex: 0 0 auto;
  color: var(--text-primary);
  font-weight: 700;
  letter-spacing: 0;
}

.nav,
.site-footer nav {
  display: flex;
  align-items: center;
  gap: 18px;
  color: var(--text-secondary);
  font-size: 14px;
}

.nav a[aria-current="page"] {
  color: var(--accent);
  font-weight: 600;
}

main {
  max-width: 960px;
  margin: 0 auto;
  padding: 42px 24px 56px;
}

.hero {
  max-width: 720px;
  margin-bottom: 32px;
}

.hero h1 {
  margin: 0 0 12px;
  font-size: 28px;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0;
}

.hero p {
  margin: 0;
  color: var(--text-secondary);
  font-size: 16px;
  line-height: 1.6;
}

.tool {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 336px;
  gap: 24px;
  align-items: start;
  margin-bottom: 44px;
}

.preview-card,
.controls {
  min-width: 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.preview-card {
  padding: 16px;
}

.upload-zone {
  display: flex;
  min-height: 360px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 8px;
  padding: 24px;
  background: var(--bg-upload);
  border: 2px dashed var(--border-hover);
  border-radius: var(--radius-lg);
  color: var(--text-secondary);
  text-align: center;
  transition: background-color 160ms ease, border-color 160ms ease;
}

.upload-zone:hover,
.upload-zone.is-dragover {
  background: var(--accent-light);
  border-color: var(--accent);
}

.upload-zone input {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
}

.upload-icon {
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  color: var(--accent);
}

.upload-icon svg {
  width: 32px;
  height: 32px;
}

.upload-title {
  color: var(--text-primary);
  font-weight: 600;
}

.upload-note,
.message {
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1.5;
}

.canvas-wrap {
  display: grid;
  max-height: 70vh;
  place-items: center;
  overflow: auto;
  background: var(--bg-upload);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
}

#gridCanvas {
  display: block;
  max-width: 100%;
  height: auto;
}

.message {
  min-height: 22px;
  margin: 10px 0 0;
}

.message.is-error {
  color: var(--error);
}

.message.is-success {
  color: var(--success);
}

.controls {
  padding: 18px;
}

.segmented-field {
  display: grid;
  gap: 8px;
  margin: 0 0 16px;
  padding: 0;
  border: 0;
}

.segmented-field legend {
  margin: 0;
  padding: 0;
  color: var(--text-secondary);
  font-size: 14px;
  line-height: 1.5;
}

.segmented-control {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4px;
  padding: 4px;
  border-radius: var(--radius-sm);
  background: #f3f4f6;
}

.segmented-option {
  min-height: 36px;
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-primary);
  font-weight: 500;
}

.segmented-option.is-active {
  background: var(--accent);
  color: #ffffff;
}

.segmented-option:focus-visible {
  outline: 2px solid var(--border-focus);
  outline-offset: 2px;
}

.control-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.field {
  display: grid;
  gap: 6px;
  color: var(--text-secondary);
  font-size: 14px;
  line-height: 1.5;
}

.field span {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.field small {
  display: block;
  margin: -2px 0 2px;
  color: var(--text-muted);
  font-size: 12px;
  font-weight: 400;
  line-height: 1.4;
}

.field-wide {
  grid-column: 1 / -1;
}

.field input,
.field select {
  min-height: 44px;
  width: 100%;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.field input[type="number"] {
  width: 80px;
  padding: 8px;
  text-align: center;
}

.field input[type="color"] {
  width: 80px;
  padding: 4px;
}

.field select {
  padding: 8px 10px;
}

.field input[type="range"] {
  min-height: 24px;
  accent-color: var(--accent);
}

.field input:focus-visible,
.field select:focus-visible,
.checks input:focus-visible,
.button:focus-visible,
.upload-zone:focus-within {
  outline: 2px solid var(--border-focus);
  outline-offset: 2px;
}

output {
  color: var(--text-primary);
  font-size: 12px;
}

.control-divider {
  height: 1px;
  margin: 18px 0;
  background: var(--border);
}

.checks {
  display: grid;
  gap: 10px;
  color: var(--text-primary);
  font-size: 14px;
}

.checks label {
  display: flex;
  min-height: 32px;
  align-items: center;
  gap: 8px;
}

.checks input {
  width: 16px;
  height: 16px;
  margin: 0;
  accent-color: var(--accent);
}

.paper-format {
  display: grid;
  gap: 14px;
}

.custom-paper-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}

.printing-guide {
  margin-top: 14px;
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: #f9fafb;
  color: var(--text-secondary);
  font-size: 13px;
  line-height: 1.5;
}

.printing-guide h3 {
  margin: 0 0 8px;
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 600;
  line-height: 1.4;
}

.printing-guide p {
  margin: 0 0 8px;
}

.printing-guide ul {
  display: grid;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.printing-guide li::before {
  content: "• ";
}

.change-image-btn {
  display: inline-flex;
  min-height: 36px;
  padding: 8px 16px;
  margin-top: 10px;
  border: 1px solid var(--border-hover);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  gap: 6px;
  transition: background-color 160ms ease, border-color 160ms ease;
}

.change-image-btn:hover {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
}

.change-image-btn svg {
  width: 16px;
  height: 16px;
}

.actions {
  display: grid;
  gap: 10px;
  margin-top: 20px;
}

.button {
  display: inline-flex;
  min-height: 46px;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-weight: 500;
  transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease;
}

.button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.primary {
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #ffffff;
}

.primary:hover:not(:disabled) {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
}

.secondary {
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-primary);
}

.secondary:hover {
  background: #f5f5f5;
  border-color: var(--border-hover);
}

.content-section {
  margin-top: 36px;
  padding-top: 34px;
  border-top: 1px solid var(--border);
}

.content-section h2 {
  margin: 0 0 12px;
  font-size: 22px;
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: 0;
}

.content-section p {
  max-width: 760px;
  margin: 0;
  color: var(--text-secondary);
}

.faq {
  display: grid;
  gap: 10px;
}

.faq h2 {
  margin-bottom: 4px;
}

.faq details {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
}

.faq summary {
  cursor: pointer;
  padding: 14px 16px;
  font-weight: 600;
  line-height: 1.4;
}

.faq details p {
  padding: 0 16px 16px;
}

.site-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  max-width: 1040px;
  margin: 0 auto;
  padding: 24px;
  border-top: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 14px;
}

@media (max-width: 800px) {
  .site-header,
  .site-footer {
    align-items: flex-start;
    flex-direction: column;
  }

  .nav,
  .site-footer nav {
    flex-wrap: wrap;
    row-gap: 8px;
  }

  main {
    padding: 32px 16px 44px;
  }

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

  .upload-zone {
    min-height: 280px;
  }

  .controls {
    padding: 16px;
  }

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

@media (max-width: 520px) {
  body {
    font-size: 15px;
  }

  .site-header,
  .site-footer {
    padding: 16px;
  }

  .hero h1 {
    font-size: 26px;
  }

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

  .custom-paper-grid {
    grid-template-columns: 1fr;
  }

  .field input[type="number"],
  .field input[type="color"] {
    width: 100%;
  }

  .preview-card {
    padding: 12px;
  }

  .upload-zone {
    min-height: 240px;
    padding: 18px;
  }
}