/* ============================
   CSS Grid Builder — style.css
   ============================ */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-primary: #4f46e5;
  --color-primary-dark: #3730a3;
  --color-primary-light: #818cf8;
  --color-bg: #f1f5f9;
  --color-surface: #ffffff;
  --color-border: #e2e8f0;
  --color-text: #1e293b;
  --color-text-secondary: #64748b;
  --color-accent: #10b981;
  --color-accent-dark: #059669;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.10);
  --touch-min: 44px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Noto Sans JP", "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
}

/* ---- Header ---- */
.site-header {
  background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
  color: #fff;
  padding: 1.25rem 1rem;
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
}

.back-link {
  display: inline-block;
  color: rgba(255,255,255,0.8);
  text-decoration: none;
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
  min-height: var(--touch-min);
  line-height: var(--touch-min);
  padding: 0 0.25rem;
}

.back-link:hover {
  color: #fff;
}

.site-header h1 {
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.3;
}

.subtitle {
  font-size: 0.875rem;
  opacity: 0.85;
  margin-top: 0.25rem;
}

/* ---- Main ---- */
main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 1rem;
}

/* ---- Ad Units ---- */
.ad-unit {
  margin: 1.25rem 0;
}

/* ---- Mode Tabs ---- */
.mode-tabs {
  display: flex;
  gap: 0.5rem;
  margin: 1rem 0 0.75rem;
}

.tab-btn {
  flex: 1;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  font-weight: 600;
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.2s;
  min-height: var(--touch-min);
}

.tab-btn:hover {
  border-color: var(--color-primary-light);
  color: var(--color-primary);
}

.tab-btn.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* ---- Tool Panel ---- */
.tool-panel {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  box-shadow: var(--shadow-sm);
}

.tool-panel.hidden {
  display: none;
}

/* ---- Preset Bar ---- */
.preset-bar {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
}

.preset-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  white-space: nowrap;
  padding-top: 0.6rem;
}

.preset-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.preset-btn {
  padding: 0.5rem 0.875rem;
  font-size: 0.8125rem;
  font-weight: 500;
  background: #eef2ff;
  color: var(--color-primary);
  border: 1px solid #c7d2fe;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s;
  min-height: var(--touch-min);
  white-space: nowrap;
}

.preset-btn:hover {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* ---- Controls Grid ---- */
.controls-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.875rem 1.25rem;
  margin-bottom: 1.5rem;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
}

.control-group label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-text-secondary);
}

.control-group input[type="text"],
.control-group select {
  padding: 0.5rem 0.75rem;
  font-size: 0.9375rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: var(--touch-min);
  -webkit-appearance: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%2364748b' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2.25rem;
  cursor: pointer;
}

.control-group input[type="text"] {
  background-image: none;
  padding-right: 0.75rem;
}

.control-group select:focus,
.control-group input[type="text"]:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 1px;
  border-color: transparent;
}

/* ---- Number Control ---- */
.number-control {
  display: flex;
  align-items: center;
  gap: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  height: var(--touch-min);
}

.number-control input[type="number"] {
  flex: 1;
  border: none;
  text-align: center;
  font-size: 1rem;
  font-weight: 600;
  background: var(--color-bg);
  color: var(--color-text);
  min-width: 0;
  height: 100%;
  padding: 0;
  -moz-appearance: textfield;
}

.number-control input[type="number"]::-webkit-outer-spin-button,
.number-control input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none;
}

.number-control input[type="number"]:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 0;
}

.num-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 100%;
  background: var(--color-surface);
  border: none;
  cursor: pointer;
  font-size: 1.25rem;
  color: var(--color-primary);
  transition: background 0.15s;
  flex-shrink: 0;
}

.num-btn:hover {
  background: #eef2ff;
}

.num-btn:active {
  background: #c7d2fe;
}

/* ---- Gap Control ---- */
.gap-control {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  min-height: var(--touch-min);
}

.gap-control input[type="range"] {
  flex: 1;
  height: 6px;
  accent-color: var(--color-primary);
  cursor: pointer;
}

.gap-value {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-primary);
  min-width: 3rem;
  text-align: right;
}

/* ---- Color input ---- */
input[type="color"] {
  width: 100%;
  height: var(--touch-min);
  padding: 0.25rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-bg);
  cursor: pointer;
}

/* ---- Preview Wrapper ---- */
.preview-wrapper {
  margin: 1.25rem 0;
}

.preview-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.section-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
}

.hint-text {
  font-size: 0.8125rem;
  color: var(--color-text-secondary);
}

/* ---- Grid Preview ---- */
.grid-preview-scroll {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 0.5rem;
}

.grid-preview {
  display: grid;
  min-width: 320px;
  min-height: 200px;
  background: #f8fafc;
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  padding: 12px;
}

.grid-cell {
  background: #c7d2fe;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  font-weight: 600;
  color: #3730a3;
  cursor: pointer;
  transition: all 0.15s;
  min-height: 60px;
  border: 2px solid transparent;
  user-select: none;
  word-break: break-all;
  padding: 0.25rem;
  text-align: center;
}

.grid-cell:hover {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.2);
}

.grid-cell.selected {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(79,70,229,0.35);
  outline: none;
}

/* ---- Span Panel ---- */
.span-panel {
  background: #f8fafc;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1rem;
  margin: 0.75rem 0 1.25rem;
}

.span-panel-title {
  font-size: 0.9375rem;
  font-weight: 600;
  margin-bottom: 0.875rem;
  color: var(--color-text);
}

.span-controls {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem 1rem;
  margin-bottom: 0.875rem;
}

.secondary-btn {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  min-height: var(--touch-min);
}

.secondary-btn:hover {
  background: #fee2e2;
  border-color: #fca5a5;
  color: #dc2626;
}

/* ---- Flex Preview ---- */
.flex-preview-scroll {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 0.5rem;
}

.flex-preview {
  display: flex;
  min-width: 320px;
  min-height: 140px;
  background: #f8fafc;
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-md);
  padding: 12px;
}

.flex-item {
  background: #a7f3d0;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8125rem;
  font-weight: 600;
  color: #065f46;
  min-width: 60px;
  min-height: 60px;
  border: 2px solid transparent;
}

/* ---- Code Output ---- */
.code-output-section {
  margin-top: 1.25rem;
}

.code-tabs {
  display: flex;
  gap: 0.375rem;
  margin-bottom: 0.5rem;
}

.code-tab {
  padding: 0.4rem 1rem;
  font-size: 0.875rem;
  font-weight: 600;
  background: var(--color-bg);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  min-height: var(--touch-min);
}

.code-tab:hover {
  border-color: var(--color-primary-light);
  color: var(--color-primary);
}

.code-tab.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.code-block-wrapper {
  position: relative;
}

.code-block {
  display: block;
  background: #0f172a;
  color: #e2e8f0;
  border-radius: var(--radius-md);
  padding: 1rem 1rem 1rem 1.25rem;
  font-family: "Fira Code", "Cascadia Code", "Consolas", monospace;
  font-size: 0.8125rem;
  line-height: 1.7;
  white-space: pre;
  overflow-x: auto;
  min-height: 80px;
  -webkit-overflow-scrolling: touch;
}

.copy-btn {
  position: absolute;
  top: 0.625rem;
  right: 0.625rem;
  padding: 0.35rem 0.875rem;
  font-size: 0.8125rem;
  font-weight: 600;
  background: var(--color-accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background 0.2s;
  min-height: var(--touch-min);
}

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

.copy-btn.copied {
  background: #6366f1;
}

/* ---- Howto Section ---- */
.howto-section {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  margin-top: 1.5rem;
}

.howto-section h2 {
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 0.75rem;
  margin-top: 1.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
}

.howto-section h2:first-of-type {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.howto-section ol,
.howto-section p {
  font-size: 0.9375rem;
  color: #475569;
  line-height: 1.75;
}

.howto-section ol {
  padding-left: 1.5rem;
}

.howto-section li {
  margin-bottom: 0.625rem;
}

.howto-section code {
  background: #f1f5f9;
  border-radius: 4px;
  padding: 0.1em 0.4em;
  font-family: "Fira Code", "Consolas", monospace;
  font-size: 0.875em;
  color: var(--color-primary);
}

.howto-section p + p {
  margin-top: 0.875rem;
}

/* ---- Footer ---- */
.site-footer {
  text-align: center;
  padding: 2rem 1rem;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-top: 2rem;
}

.site-footer a {
  color: var(--color-text-secondary);
  text-decoration: underline;
}

.site-footer p + p {
  margin-top: 0.25rem;
}

/* ============================
   Responsive
   ============================ */
@media (min-width: 640px) {
  .site-header h1 {
    font-size: 1.625rem;
  }

  main {
    padding: 1.5rem 2rem;
  }

  .controls-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .span-controls {
    grid-template-columns: repeat(4, 1fr);
  }

  .mode-tabs {
    max-width: 360px;
  }
}

@media (min-width: 900px) {
  .controls-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}