/* ============================================================
   Reset & Base
   ============================================================ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --color-primary:   #4f46e5;
  --color-primary-d: #3730a3;
  --color-primary-l: #eef2ff;
  --color-bg:        #fafbfc;
  --color-surface:   #ffffff;
  --color-text:      #1e293b;
  --color-muted:     #64748b;
  --color-border:    #e2e8f0;
  --color-success:   #059669;
  --color-error:     #dc2626;
  --color-warning:   #d97706;

  --accent-json:     #3b82f6;
  --accent-color:    #8b5cf6;
  --accent-text:     #10b981;
  --accent-url:      #f59e0b;
  --accent-time:     #f97316;
  --accent-base64:   #14b8a6;
  --accent-calc:     #6366f1;
  --accent-english:  #059669;

  --radius:          12px;
  --radius-sm:       8px;
  --shadow:          0 2px 8px rgba(0,0,0,0.06);
  --shadow-lg:       0 8px 24px rgba(0,0,0,0.1);
  --transition:      0.2s ease;
  --font:            'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', system-ui, -apple-system, sans-serif;
  --font-mono:       'Fira Code', 'SF Mono', 'Cascadia Code', 'Consolas', monospace;
}

html { font-size: 16px; scroll-behavior: smooth; scrollbar-gutter: stable; }

body {
  font-family: var(--font);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ============================================================
   Layout
   ============================================================ */
.container {
  width: 100%;
  max-width: 1024px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

main.container { flex: 1; padding-top: 2rem; padding-bottom: 3rem; }

/* ============================================================
   Header
   ============================================================ */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

.site-header .container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  height: 60px;
  position: relative;
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--color-text);
  font-weight: 700;
  font-size: 1.05rem;
  text-decoration: none;
}

.logo-link:hover { color: var(--color-primary); text-decoration: none; }

.logo-icon {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--color-primary), #818cf8);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: 0.85rem;
  font-weight: 800;
  flex-shrink: 0;
}

/* ============================================================
   Header Back Arrow
   ============================================================ */
.header-back {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  color: var(--color-muted);
  text-decoration: none;
  transition: all var(--transition);
  flex-shrink: 0;
  position: absolute;
  left: -0.5rem;
  top: 50%;
  transform: translateY(-50%);
}

.header-back svg {
  width: 18px;
  height: 18px;
}

.header-back:hover {
  color: var(--color-primary);
  background: var(--color-primary-l);
  text-decoration: none;
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  background: linear-gradient(135deg, var(--color-primary) 0%, #7c3aed 100%);
  color: #fff;
  border-radius: var(--radius);
  padding: 3rem 2.5rem;
  margin-bottom: 2rem;
  text-align: center;
}

.hero h2 {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  letter-spacing: -0.02em;
}

.hero p {
  opacity: 0.9;
  max-width: 520px;
  margin: 0 auto;
  font-size: 1.05rem;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.6rem 1.25rem;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  font-family: var(--font);
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
}

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

.btn--primary:hover { background: var(--color-primary-d); transform: translateY(-1px); box-shadow: var(--shadow); }

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

.btn--secondary:hover { background: var(--color-border); transform: translateY(-1px); }

.btn--small {
  padding: 0.35rem 0.75rem;
  font-size: 0.8rem;
}

.btn--icon {
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: var(--radius-sm);
}

/* ============================================================
   Search & Filters
   ============================================================ */
.toolbar {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 2rem;
}

.search-wrapper {
  position: relative;
  max-width: 480px;
  width: 100%;
}

.search-wrapper input {
  width: 100%;
  padding: 0.7rem 1rem 0.7rem 2.5rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-family: var(--font);
  background: var(--color-surface);
  color: var(--color-text);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}

.search-wrapper input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-l);
}

.search-icon {
  position: absolute;
  left: 0.85rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--color-muted);
  pointer-events: none;
  font-size: 0.9rem;
}

.category-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.filter-pill {
  padding: 0.4rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  background: var(--color-surface);
  color: var(--color-muted);
  transition: all var(--transition);
  font-family: var(--font);
}

.filter-pill:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter-pill.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* ============================================================
   Card Grid (Index)
   ============================================================ */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2rem;
}

.tool-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  cursor: pointer;
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: var(--color-text);
  position: relative;
  overflow: hidden;
}

.tool-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--card-accent, var(--color-primary));
  transition: height var(--transition);
}

.tool-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--card-accent, var(--color-primary));
  text-decoration: none;
  color: var(--color-text);
}

.tool-card:hover::before { height: 5px; }

.card__icon {
  font-size: 2.25rem;
  margin-bottom: 1rem;
  line-height: 1;
}

.card__title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--color-text);
}

.card__desc {
  font-size: 0.875rem;
  color: var(--color-muted);
  line-height: 1.55;
  margin-bottom: 1rem;
  flex: 1;
}

.card__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.75rem;
}

.card__tag {
  font-size: 0.72rem;
  font-weight: 500;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  background: color-mix(in srgb, var(--card-accent, var(--color-primary)) 10%, transparent);
  color: var(--card-accent, var(--color-primary));
}

.card__cta {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--card-accent, var(--color-primary));
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

/* Card accent variants */
.tool-card--json  { --card-accent: var(--accent-json); }
.tool-card--color { --card-accent: var(--accent-color); }
.tool-card--text  { --card-accent: var(--accent-text); }
.tool-card--url   { --card-accent: var(--accent-url); }
.tool-card--time  { --card-accent: var(--accent-time); }
.tool-card--base64 { --card-accent: var(--accent-base64); }
.tool-card--calc  { --card-accent: var(--accent-calc); }
.tool-card--english { --card-accent: var(--accent-english); }

/* ============================================================
   Tool Page Shared Styles
   ============================================================ */
.tool-page {
  /* full width — same as home page content */
}

.tool-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.tool-desc {
  color: var(--color-muted);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

/* ============================================================
   Form Elements (shared by tools)
   ============================================================ */
.tool-input {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: var(--font-mono);
  background: var(--color-surface);
  color: var(--color-text);
  resize: vertical;
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
  line-height: 1.5;
}

.tool-input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-l);
}

.tool-label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.4rem;
  color: var(--color-text);
}

.tool-output {
  width: 100%;
  min-height: 120px;
  padding: 0.75rem 1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: var(--font-mono);
  background: #f8fafc;
  color: var(--color-text);
  line-height: 1.5;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.tool-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
}

@media (max-width: 640px) {
  .tool-row { grid-template-columns: 1fr; }
}

.tool-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 1rem 0;
}

.form-group {
  margin-bottom: 1.25rem;
}

/* ============================================================
   Toast / Copy feedback
   ============================================================ */
.toast {
  position: fixed;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-text);
  color: #fff;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 500;
  z-index: 999;
  box-shadow: var(--shadow-lg);
  animation: toast-in 0.25s ease, toast-out 0.25s ease 1.75s forwards;
  pointer-events: none;
}

@keyframes toast-in {
  from { opacity: 0; transform: translateX(-50%) translateY(10px); }
  to   { opacity: 1; transform: translateX(-50%) translateY(0); }
}

@keyframes toast-out {
  from { opacity: 1; transform: translateX(-50%) translateY(0); }
  to   { opacity: 0; transform: translateX(-50%) translateY(-10px); }
}

/* ============================================================
   Footer
   ============================================================ */
.site-footer {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: 1.25rem 0;
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-muted);
}

/* ============================================================
   404 Page
   ============================================================ */
.not-found-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  text-align: center;
  gap: 1rem;
}

.not-found-page .icon { font-size: 5rem; line-height: 1; }
.not-found-page h2    { font-size: 1.75rem; font-weight: 700; }
.not-found-page p     { color: var(--color-muted); max-width: 360px; }

/* ============================================================
   Offline Page
   ============================================================ */
.offline-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  text-align: center;
  gap: 1rem;
}

.offline-page .icon { font-size: 4rem; }
.offline-page h2    { font-size: 1.5rem; }
.offline-page p     { color: var(--color-muted); }

/* ============================================================
   Color Swatch (color-converter)
   ============================================================ */
.color-swatch {
  width: 100%;
  height: 120px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  transition: background 0.3s ease;
}

.color-results {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1rem;
  margin-top: 1.25rem;
}

.color-result-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 1rem;
}

.color-result-card label {
  display: block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.35rem;
}

.color-result-card code {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--color-text);
  word-break: break-all;
}

/* ============================================================
   JSON Syntax Highlighting
   ============================================================ */
.json-output { font-family: var(--font-mono); font-size: 0.85rem; line-height: 1.6; }
.json-key    { color: #0550ae; }
.json-string { color: #0a3069; }
.json-number { color: #cf222e; }
.json-bool   { color: #8250df; }
.json-null   { color: #6e7781; }
.json-error  { color: #dc2626; font-weight: 600; }

/* ============================================================
   Text Diff
   ============================================================ */
.diff-line {
  padding: 0.15rem 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  border-radius: 3px;
  white-space: pre-wrap;
  word-break: break-all;
}

.diff-added   { background: #dcfce7; color: #166534; }
.diff-removed { background: #fef2f2; color: #991b1b; }
.diff-unchanged { color: var(--color-muted); }

/* ============================================================
   Image Preview (base64)
   ============================================================ */
.image-preview {
  max-width: 100%;
  max-height: 300px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-border);
  margin-top: 1rem;
}

/* ============================================================
   Empty State
   ============================================================ */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--color-muted);
}

.empty-state .icon { font-size: 3rem; margin-bottom: 0.75rem; }
.empty-state p     { font-size: 0.95rem; }

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 640px) {
  .hero { padding: 2rem 1.25rem; }
  .hero h2 { font-size: 1.5rem; }
  .hero p { font-size: 0.95rem; }
  .tool-grid { grid-template-columns: 1fr; }
  .tool-title { font-size: 1.4rem; }
  .toolbar { gap: 0.75rem; }
  .search-wrapper { max-width: 100%; }
}

/* ============================================================
   Print
   ============================================================ */
@media print {
  .site-header, .site-footer, .btn, .toolbar { display: none !important; }
  body { background: #fff; }
  .tool-output { border: 1px solid #ccc; }
}