:root[data-theme="light"] {
  --bg: #f3f3ee;
  --panel: #ffffff;
  --card: #ffffff;
  --border: #e5e5e5;
  --text: #1a1a1a;
  --text-muted: #6b6b6b;
  --success: #10a37f;
  --danger: #e5484d;
  --accent: #da7756;
}
:root[data-theme="dark"] {
  --bg: #1a1a1a;
  --panel: #252525;
  --card: #2a2a2a;
  --border: #3a3a3a;
  --text: #e5e5e5;
  --text-muted: #9a9a9a;
  --success: #10b981;
  --danger: #ef4444;
  --accent: #da7756;
}
* { box-sizing: border-box; }
body {
  background-color: var(--bg);
  color: var(--text);
  font-family: 'Inter', -apple-system, sans-serif;
  -webkit-font-smoothing: antialiased;
  margin: 0;
  display: flex;
  height: 100vh;
  overflow: hidden;
  transition: background-color 0.2s, color 0.2s;
}
.hero-section {
  height: 100vh;
  width: 100vw;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  position: relative;
  text-align: center;
  padding: 0 24px;
}
.hero-bg-mark {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 35vw;
  font-weight: 800;
  color: var(--text);
  opacity: 0.04;
  z-index: 1;
  user-select: none;
  letter-spacing: -0.05em;
  pointer-events: none;
}
.hero-content { z-index: 10; display: flex; flex-direction: column; align-items: center; }
.badge {
  color: var(--text-muted);
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 0.7rem;
  margin-bottom: 24px;
  border: 1px solid var(--border);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  font-weight: 500;
}
.hero-title { font-size: 4rem; font-weight: 600; line-height: 1.05; margin-bottom: 24px; letter-spacing: -0.04em; }
.hero-subtitle { font-size: 1.1rem; color: var(--text-muted); max-width: 600px; margin-bottom: 40px; line-height: 1.6; }
.btn-primary {
  background: var(--text); color: var(--bg); border: none; padding: 12px 24px;
  font-size: 0.95rem; border-radius: 6px; cursor: pointer; transition: transform 0.2s; font-weight: 500;
}
.btn-primary:hover { transform: scale(1.02); }
.developer-footer { position: absolute; bottom: 24px; font-size: 0.75rem; color: var(--text-muted); letter-spacing: 0.5px; }
.developer-footer strong { color: var(--text); font-weight: 500; }

.app-shell { display: grid; grid-template-columns: 260px 1fr; width: 100vw; height: 100vh; }
#sidebar-root { height: 100vh; display: flex; flex-direction: column; }
.sidebar {
  background: var(--panel); border-right: 1px solid var(--border); padding: 24px 20px;
  box-sizing: border-box; height: 100%; width: 100%; overflow: hidden; display: flex; flex-direction: column; gap: 16px;
}
.sidebar-brand { font-weight: 600; font-size: 1.05rem; letter-spacing: -0.02em; display: flex; align-items: center; gap: 8px; text-decoration: none; color: var(--text); flex-shrink: 0; }
.sidebar-brand .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--accent); }
.sidebar-nav-row { display: flex; gap: 8px; flex-shrink: 0; }
.sidebar-nav-row .icon-btn { flex: 1; text-decoration: none; }
.sidebar-scroll { flex: 1; overflow-y: auto; overflow-x: hidden; margin: 0 -20px; padding: 0 20px 12px 20px; }
.sidebar-controls { display: flex; gap: 8px; flex-shrink: 0; }
.lang-switch { display: flex; gap: 6px; }
.icon-btn, .lang-switch button {
  background: transparent; color: var(--text-muted); border: 1px solid var(--border); padding: 6px 10px;
  border-radius: 6px; cursor: pointer; font-size: 0.75rem; font-weight: 500; display: flex; align-items: center;
  justify-content: center; transition: color 0.2s, border-color 0.2s;
}
.lang-btn.active { color: var(--text); border-color: var(--text-muted); }
.icon-btn:hover, .lang-switch button:hover { color: var(--text); border-color: var(--text-muted); }
.input-field, .code-area {
  width: 100%; padding: 10px 14px; border: 1px solid var(--border); background: var(--bg); color: var(--text);
  border-radius: 6px; font-family: inherit; font-size: 0.9rem; box-sizing: border-box; transition: border-color 0.2s, box-shadow 0.2s;
}
.input-field:focus, .code-area:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 1px var(--accent); }
.input-label { font-size: 0.8rem; color: var(--text-muted); margin-bottom: 8px; display: block; font-weight: 500; }

.sidebar-category { font-size: 0.7rem; text-transform: uppercase; letter-spacing: 1.2px; color: var(--text-muted); font-weight: 600; }
.sidebar-cat-group { margin-bottom: 4px; }
.sidebar-category-toggle {
  width: 100%; display: flex; align-items: center; justify-content: space-between;
  background: none; border: none; cursor: pointer; padding: 8px 12px 4px 12px; margin: 0;
}
.sidebar-category-toggle:hover .sidebar-category { color: var(--text); }
.cat-chevron { color: var(--text-muted); transition: transform 0.25s ease; flex-shrink: 0; }
.cat-chevron.collapsed { transform: rotate(-90deg); }
.tool-list-rows { display: grid; grid-template-rows: 1fr; transition: grid-template-rows 0.28s cubic-bezier(0.4, 0, 0.2, 1); }
.tool-list-rows.collapsed { grid-template-rows: 0fr; }
.tool-list-clip { overflow: hidden; min-height: 0; }
.tool-list { display: flex; flex-direction: column; gap: 2px; padding-top: 2px; }
.tool-list a {
  display: flex; align-items: center; gap: 10px; color: var(--text-muted); text-decoration: none;
  padding: 8px 12px; font-size: 0.85rem; border-radius: 6px; transition: background 0.2s, color 0.2s;
}
.tool-list a:hover, .tool-list a.active { background: var(--border); color: var(--text); }
.tool-list svg { flex-shrink: 0; }

.workspace { background: var(--bg); padding: 48px 64px; overflow-y: auto; height: 100vh; box-sizing: border-box; }
.category-block { margin-bottom: 40px; }
.category-heading { font-size: 0.75rem; text-transform: uppercase; letter-spacing: 1.5px; color: var(--accent); font-weight: 600; margin-bottom: 16px; }
.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 20px; }
.tool-card {
  border: 1px solid var(--border); border-radius: 10px; padding: 24px; cursor: pointer;
  background: var(--card); transition: all 0.2s ease; text-decoration: none; color: inherit; display: block;
}
.tool-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.tool-icon { width: 40px; height: 40px; color: var(--text); display: flex; align-items: center; margin-bottom: 16px; }
.tool-card h3 { font-size: 0.95rem; font-weight: 500; margin: 0; letter-spacing: -0.01em; }
.tool-card p { font-size: 0.78rem; color: var(--text-muted); margin: 6px 0 0 0; line-height: 1.4; }

.back-btn {
  background: none; border: none; color: var(--text-muted); cursor: pointer; margin-bottom: 32px;
  font-size: 0.85rem; display: flex; align-items: center; gap: 8px; padding: 0; transition: color 0.2s;
}
.back-btn:hover { color: var(--text); }
.result-card {
  background: var(--card); padding: 32px; border-radius: 12px; border: 1px solid var(--border);
  display: flex; flex-direction: column; justify-content: center;
}
.result-label { color: var(--text-muted); font-size: 0.75rem; font-weight: 500; text-transform: uppercase; letter-spacing: 1.5px; margin: 0 0 8px 0; }
.result-value { font-size: 2.5rem; font-weight: 500; letter-spacing: -0.04em; margin: 0; }
.success-text { color: var(--success); }
.danger-text { color: var(--danger); }
.status-badge { font-size: 0.75rem; font-weight: 500; padding: 4px 12px; border-radius: 20px; background: var(--bg); border: 1px solid var(--border); color: var(--text-muted); }
.success-badge { color: var(--success); border-color: rgba(16, 163, 127, 0.3); background: rgba(16, 163, 127, 0.05); }
.danger-badge { color: var(--danger); border-color: rgba(229, 72, 77, 0.3); background: rgba(229, 72, 77, 0.05); }
.error-box { background: rgba(229, 72, 77, 0.1); color: var(--danger); padding: 12px 16px; border-radius: 6px; font-size: 0.85rem; margin-top: 16px; display: none; font-family: monospace; }
.info-box { background: rgba(0,150,150,0.08); color: var(--accent); padding: 12px 16px; border-radius: 6px; font-size: 0.8rem; margin-top: 16px; line-height: 1.5; }
.tool-article { margin-top: 48px; padding-top: 32px; border-top: 1px solid var(--border); color: var(--text-muted); font-size: 0.9rem; line-height: 1.7; max-width: 720px; }
.tool-article h2 { color: var(--text); font-size: 1.1rem; font-weight: 600; margin-bottom: 8px; }
.tool-article h2:not(:first-child) { margin-top: 24px; }
.tool-faq { margin-top: 24px; }
.faq-item { margin-bottom: 16px; }
.faq-question { color: var(--text); font-size: 0.95rem; font-weight: 600; margin: 0 0 4px 0; }
.faq-answer { margin: 0; }

::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 10px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }
* { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }

@media (max-width: 860px) {
  .app-shell { grid-template-columns: 1fr; }
  #sidebar-root { display: none; }
  .workspace { padding: 24px; }
  .hero-bg-mark { font-size: 50vw; }
}