/* ===== Variables ===== */
:root {
  --bg: #0d1117;
  --bg-secondary: #161b22;
  --bg-tertiary: #21262d;
  --border: #30363d;
  --text: #e6edf3;
  --text-muted: #8b949e;
  --accent: #58a6ff;
  --accent-hover: #79c0ff;
  --green: #3fb950;
  --red: #f85149;
  --yellow: #d29922;
  --orange: #db6d28;
  --purple: #bc8cff;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  --font-sans: 'Inter', -apple-system, sans-serif;
  --radius: 8px;
  --shadow: 0 2px 8px rgba(0,0,0,.3);
}

[data-theme="light"] {
  --bg: #ffffff;
  --bg-secondary: #f6f8fa;
  --bg-tertiary: #e1e4e8;
  --border: #d0d7de;
  --text: #1f2328;
  --text-muted: #656d76;
  --accent: #0969da;
  --accent-hover: #0550ae;
  --green: #1a7f37;
  --red: #cf222e;
  --yellow: #9a6700;
  --shadow: 0 2px 8px rgba(0,0,0,.1);
}

/* ===== Reset ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  transition: background .2s, color .2s;
}

/* ===== Header ===== */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 24px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
  gap: 8px;
}
.header-left { display: flex; align-items: center; gap: 16px; }
.header-right { display: flex; align-items: center; gap: 16px; }
.logo {
  font-family: var(--font-mono);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--text);
}
.logo-brace { color: var(--accent); }
.tagline { color: var(--text-muted); font-size: .85rem; }

/* Tabs */
.tabs { display: flex; gap: 4px; }
.tab {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: .85rem;
  font-family: var(--font-sans);
  font-weight: 500;
  transition: all .15s;
}
.tab:hover { color: var(--text); background: var(--bg-tertiary); }
.tab.active { color: var(--accent); border-color: var(--accent); background: var(--bg-tertiary); }

/* Theme Toggle */
.theme-toggle {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text-muted);
  width: 36px; height: 36px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all .15s;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }
[data-theme="dark"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: none; }

/* ===== Status Bar ===== */
.status-bar {
  padding: 6px 24px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  font-size: .8rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}
.status-bar.error { color: var(--red); background: rgba(248,81,73,.08); }
.status-bar.success { color: var(--green); background: rgba(63,185,80,.08); }

/* ===== Toolbar ===== */
.toolbar {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.btn {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: .8rem;
  font-family: var(--font-sans);
  font-weight: 500;
  transition: all .15s;
  white-space: nowrap;
}
.btn:hover { border-color: var(--accent); color: var(--accent); }
.btn-clear { color: var(--red); }
.btn-clear:hover { border-color: var(--red); }
.separator { width: 1px; height: 24px; background: var(--border); margin: 0 4px; }
.spacer { flex: 1; }
.indent-label {
  font-size: .8rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 6px;
}
.indent-label select {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 4px 8px;
  border-radius: 4px;
  font-size: .8rem;
  font-family: var(--font-sans);
}

/* ===== Editor ===== */
.panel { display: flex; flex-direction: column; }
.panel.hidden { display: none; }

.editor-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  flex: 1;
  min-height: 60vh;
}
.editor {
  background: var(--bg);
  color: var(--text);
  border: none;
  padding: 16px 20px;
  font-family: var(--font-mono);
  font-size: .875rem;
  line-height: 1.6;
  resize: none;
  outline: none;
  overflow: auto;
  tab-size: 2;
}
.editor::placeholder { color: var(--text-muted); opacity: .6; }
.output {
  background: var(--bg-secondary);
  border-left: 1px solid var(--border);
  overflow: auto;
  position: relative;
}
.output code { white-space: pre; }
.output-wrap { position: relative; overflow: auto; background: var(--bg-secondary); border-left: 1px solid var(--border); }
.output-wrap .editor { border: none; }
.line-numbers {
  position: absolute;
  top: 0; left: 0;
  padding: 16px 0;
  text-align: right;
  color: var(--text-muted);
  font-family: var(--font-mono);
  font-size: .75rem;
  line-height: 1.6;
  user-select: none;
  opacity: .5;
  pointer-events: none;
  width: 40px;
}
.output-wrap .editor { padding-left: 50px; }

/* Syntax highlighting */
.json-key { color: var(--accent); }
.json-string { color: var(--green); }
.json-number { color: var(--orange); }
.json-bool { color: var(--purple); }
.json-null { color: var(--red); }

/* ===== Tree View ===== */
.tree-wrap {
  flex: 1;
  min-height: 60vh;
  overflow: auto;
  padding: 16px 24px;
}
.tree-info { color: var(--text-muted); font-size: .8rem; margin-left: 8px; }
.tree-view { font-family: var(--font-mono); font-size: .85rem; line-height: 1.7; }
.tree-node { padding-left: 20px; }
.tree-toggle {
  cursor: pointer;
  user-select: none;
  color: var(--text-muted);
  display: inline-block;
  width: 16px;
}
.tree-toggle:hover { color: var(--accent); }
.tree-key { color: var(--accent); }
.tree-colon { color: var(--text-muted); }
.tree-value-string { color: var(--green); }
.tree-value-number { color: var(--orange); }
.tree-value-bool { color: var(--purple); }
.tree-value-null { color: var(--red); }
.tree-bracket { color: var(--text-muted); }
.tree-children { overflow: hidden; }
.tree-children.collapsed { display: none; }
.tree-count { color: var(--text-muted); font-size: .75rem; }

/* ===== Diff ===== */
.diff-wrap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  min-height: 30vh;
}
.diff-col { display: flex; flex-direction: column; }
.diff-col + .diff-col { border-left: 1px solid var(--border); }
.diff-label {
  padding: 6px 16px;
  background: var(--bg-tertiary);
  font-size: .75rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .5px;
}
.diff-col .editor { flex: 1; }
.diff-result-wrap { border-top: 1px solid var(--border); }
.diff-output {
  min-height: 20vh;
  padding: 16px 20px;
  background: var(--bg-secondary);
  font-family: var(--font-mono);
  font-size: .85rem;
  line-height: 1.6;
  overflow: auto;
  white-space: pre;
}
.diff-info { color: var(--text-muted); font-size: .8rem; margin-left: 8px; }
.diff-add { color: var(--green); background: rgba(63,185,80,.1); display: block; }
.diff-remove { color: var(--red); background: rgba(248,81,73,.1); display: block; }
.diff-same { color: var(--text-muted); display: block; }

/* ===== Convert ===== */
#panel-convert .editor-wrap { min-height: 60vh; }
#convertMode {
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: .8rem;
  font-family: var(--font-sans);
}

/* ===== SEO Section ===== */
.seo-section {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: 48px 24px;
}
.seo-content { max-width: 1000px; margin: 0 auto; }
.seo-content h2 {
  font-size: 1.5rem;
  margin-bottom: 12px;
  color: var(--text);
}
.seo-content > p {
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 32px;
  font-size: .95rem;
}
.seo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}
.seo-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}
.seo-card h3 { font-size: .95rem; margin-bottom: 8px; }
.seo-card p { color: var(--text-muted); font-size: .85rem; line-height: 1.6; }

/* ===== Footer ===== */
.footer {
  border-top: 1px solid var(--border);
  padding: 20px 24px;
  background: var(--bg-secondary);
}
.footer-content {
  max-width: 1000px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}
.footer-tools, .footer-meta {
  font-size: .8rem;
  color: var(--text-muted);
}
.footer a {
  color: var(--accent);
  text-decoration: none;
}
.footer a:hover { text-decoration: underline; }

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .header { padding: 10px 12px; }
  .toolbar { padding: 8px 12px; }
  .editor-wrap, .diff-wrap { grid-template-columns: 1fr; }
  .output-wrap, .diff-col + .diff-col { border-left: none; border-top: 1px solid var(--border); }
  .tabs { overflow-x: auto; }
  .footer-content { flex-direction: column; text-align: center; }
}

/* ===== Drag & Drop Overlay ===== */
.drag-over::after {
  content: '📁 Drop JSON file here';
  position: fixed;
  inset: 0;
  background: rgba(88,166,255,.1);
  border: 3px dashed var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: var(--accent);
  z-index: 100;
  pointer-events: none;
  backdrop-filter: blur(4px);
}