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

[data-theme="dark"] {
  --bg-0: #08080c; --bg-1: #0e0e14; --bg-2: #14141e; --bg-3: #1a1a28; --bg-4: #222234;
  --border-1: #1e1e30; --border-2: #2c2c44; --border-3: #3a3a55;
  --text-1: #eaeaf2; --text-2: #a0a0b8; --text-3: #8a8aa6; --text-4: #8585a2;
  --shadow-soft: rgba(0,0,0,0.35); --grid-line: rgba(255,255,255,0.013);
  --glow-mult: 1; --toggle-knob: #f0c040;
  --toggle-icon-sun: 0; --toggle-icon-moon: 1; --btn-text: #08080c;
}
[data-theme="light"] {
  --bg-0: #f4f4f8; --bg-1: #eaeaef; --bg-2: #e0e0e8; --bg-3: #d5d5e0; --bg-4: #c8c8d5;
  --border-1: #d0d0dc; --border-2: #bbbbc8; --border-3: #a5a5b5;
  --text-1: #1a1a2e; --text-2: #44445a; --text-3: #70708a; --text-4: #9090a5;
  --shadow-soft: rgba(0,0,0,0.06); --grid-line: rgba(0,0,0,0.03);
  --glow-mult: 0.5; --toggle-knob: #5568ee;
  --toggle-icon-sun: 1; --toggle-icon-moon: 0; --btn-text: #ffffff;
}
:root {
  --green: #00c78e; --green-dim: rgba(0,199,142,0.12); --green-glow: rgba(0,199,142,0.18);
  --purple: #7c4dff; --purple-dim: rgba(124,77,255,0.12); --purple-glow: rgba(124,77,255,0.18);
  --coral: #ff5c8a; --coral-dim: rgba(255,92,138,0.12); --coral-glow: rgba(255,92,138,0.18);
  --accent: var(--green); --accent-dim: var(--green-dim); --accent-glow: var(--green-glow);
  --radius: 14px; --radius-sm: 10px; --radius-xs: 6px;
  --mono: 'JetBrains Mono', monospace; --sans: 'DM Sans', system-ui, sans-serif;
}
[data-theme="light"] {
  --green-dim: rgba(0,199,142,0.1); --green-glow: rgba(0,199,142,0.12);
  --purple-dim: rgba(124,77,255,0.1); --purple-glow: rgba(124,77,255,0.12);
  --coral-dim: rgba(255,92,138,0.1); --coral-glow: rgba(255,92,138,0.12);
}

html { background: var(--bg-0); transition: background 0.4s ease; }
[data-theme="dark"] { color-scheme: dark; }
[data-theme="light"] { color-scheme: light; }
body {
  font-family: var(--sans); color: var(--text-1); background: var(--bg-0);
  min-height: 100vh; line-height: 1.5; transition: background 0.4s ease, color 0.4s ease;
}
body::before {
  content: ''; position: fixed; inset: 0;
  background: radial-gradient(ellipse 80% 60% at 20% 10%, var(--accent-dim) 0%, transparent 60%),
              radial-gradient(ellipse 60% 50% at 80% 90%, var(--purple-dim) 0%, transparent 60%);
  pointer-events: none; z-index: 0; transition: background 0.6s ease; opacity: var(--glow-mult);
}
body::after {
  content: ''; position: fixed; inset: 0;
  background-image: linear-gradient(var(--grid-line) 1px, transparent 1px),
                    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 50px 50px; pointer-events: none; z-index: 0;
}
.app { position: relative; z-index: 1; max-width: 1200px; margin: 0 auto; padding: 44px 24px 100px; }

.site-header {
  background: var(--bg-1);
  border-bottom: 1px solid var(--border-1);
  padding: 0 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}
.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.site-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-1);
}
.brand-icon {
  width: 36px; height: 36px;
  background: linear-gradient(135deg, var(--green), var(--purple));
  border-radius: var(--radius-xs);
  display: flex; align-items: center; justify-content: center;
  font-size: 18px; flex-shrink: 0;
}
.brand-name {
  font-family: var(--mono);
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 3px;
  background: linear-gradient(135deg, var(--green), var(--purple), var(--coral));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.brand-sub {
  display: block;
  font-size: 11px;
  color: var(--text-3);
  font-weight: 400;
  letter-spacing: 0.02em;
  margin-top: 1px;
  -webkit-text-fill-color: var(--text-3);
  background: none;
}
.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}
.privacy-badge {
  display: flex; align-items: center; gap: 6px; padding: 6px 12px;
  background: rgba(0, 199, 142, 0.1); color: var(--green); border-radius: 100px;
  font-size: 12px; font-weight: 500; letter-spacing: 0.01em;
}
.privacy-dot {
  width: 6px; height: 6px; border-radius: 50%; background: var(--green);
  animation: pulse-privacy 2s ease infinite;
}
@keyframes pulse-privacy { 0%, 100% { opacity: 1; } 50% { opacity: 0.4; } }

.theme-toggle {
  width: 56px; height: 30px;
  background: var(--bg-3); border: 1px solid var(--border-2); border-radius: 20px;
  cursor: pointer; transition: all 0.35s ease; display: flex; align-items: center;
  padding: 3px;
}
.theme-toggle:hover { border-color: var(--border-3); box-shadow: 0 2px 12px var(--shadow-soft); }
.theme-toggle-knob {
  width: 22px; height: 22px; border-radius: 50%; background: var(--toggle-knob);
  transition: all 0.35s cubic-bezier(0.4,0,0.2,1); display: flex; align-items: center;
  justify-content: center; box-shadow: 0 2px 8px var(--shadow-soft); position: relative;
}
[data-theme="dark"] .theme-toggle-knob { transform: translateX(0); }
[data-theme="light"] .theme-toggle-knob { transform: translateX(26px); }
.theme-toggle-knob svg { width: 14px; height: 14px; position: absolute; }
.toggle-sun { opacity: var(--toggle-icon-sun); transition: opacity 0.3s; color: #fff; }
.toggle-moon { opacity: var(--toggle-icon-moon); transition: opacity 0.3s; color: #1a1a2e; }

@keyframes logoIn { from { opacity: 0; filter: blur(8px); letter-spacing: 26px; } }
@keyframes slideUp { from { opacity: 0; transform: translateY(12px); } }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes pulse { 0%,100%{opacity:1}50%{opacity:0.5} }

.hero-banner {
  text-align: center;
  margin-bottom: 36px;
  animation: slideUp 0.7s ease backwards;
}
.hero-logo {
  font-family: var(--mono);
  font-size: 50px;
  font-weight: 700;
  letter-spacing: 14px;
  background: linear-gradient(135deg, var(--green), var(--purple), var(--coral));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  animation: logoIn 0.9s ease backwards;
}
.hero-tagline {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--text-4);
  letter-spacing: 5px;
  text-transform: uppercase;
  animation: slideUp 0.7s 0.15s ease backwards;
}
.hero-note {
  font-size: 12px;
  color: var(--text-3);
  margin-top: 10px;
  animation: slideUp 0.7s 0.25s ease backwards;
}

.tabs {
  display: flex; gap: 6px; background: var(--bg-1); border: 1px solid var(--border-1);
  border-radius: 18px; padding: 6px; margin-bottom: 36px; animation: slideUp 0.7s 0.3s ease backwards;
  transition: background 0.4s, border-color 0.4s;
}
.tab {
  flex: 1; padding: 14px 16px; border: none; border-radius: 13px; background: transparent;
  color: var(--text-3); font-family: var(--sans); font-size: 14px; font-weight: 500;
  cursor: pointer; transition: all 0.25s ease;
  display: flex; align-items: center; justify-content: center; gap: 10px;
}
.tab:hover { color: var(--text-2); background: var(--bg-2); }
.tab.active { background: var(--bg-3); color: var(--text-1); box-shadow: 0 0 24px var(--accent-dim); }
.tab-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.tab[data-tab="audio"] .tab-dot { background: var(--green); }
.tab[data-tab="video"] .tab-dot { background: var(--purple); }
.tab[data-tab="image"] .tab-dot { background: var(--coral); }

.panel { display: none; animation: fadeIn 0.3s ease; }
.panel.active { display: block; }

.dropzone {
  border: 2px dashed var(--border-2); border-radius: var(--radius); padding: 56px 32px;
  text-align: center; cursor: pointer; transition: all 0.3s ease; background: var(--bg-1);
}
.dropzone:hover, .dropzone.dragover { border-color: var(--accent); background: var(--bg-2); box-shadow: inset 0 0 60px var(--accent-dim), 0 0 0 3px var(--accent-dim); }
.drop-icon { font-size: 42px; margin-bottom: 14px; display: block; opacity: 0.85; }
.drop-label { font-size: 15px; color: var(--text-2); margin-bottom: 8px; font-weight: 500; }
.drop-hint { font-size: 11px; color: var(--text-4); font-family: var(--mono); letter-spacing: 0.3px; line-height: 1.7; }
.dropzone input[type="file"] { display: none; }

.file-bar {
  display: none; align-items: center; gap: 14px; background: var(--bg-2);
  border: 1px solid var(--border-1); border-radius: var(--radius-sm);
  padding: 16px 20px; margin-top: 16px; transition: background 0.4s, border-color 0.4s;
}
.file-bar.show { display: flex; }
.file-bar-icon {
  width: 44px; height: 44px; border-radius: var(--radius-xs); background: var(--accent-dim);
  display: flex; align-items: center; justify-content: center; font-size: 20px; flex-shrink: 0;
}
.file-bar-meta { flex: 1; min-width: 0; }
.file-bar-name { font-weight: 600; font-size: 13px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-bar-size { font-size: 11px; color: var(--text-3); margin-top: 2px; font-family: var(--mono); }
.file-bar-x {
  width: 32px; height: 32px; border: 1px solid var(--border-2); border-radius: var(--radius-xs);
  background: none; color: var(--text-3); font-size: 16px; cursor: pointer;
  display: flex; align-items: center; justify-content: center; transition: all 0.2s; flex-shrink: 0;
}
.file-bar-x:hover { border-color: var(--coral); color: var(--coral); background: var(--coral-dim); }

.fmt-section { display: none; margin-top: 22px; }
.fmt-section.show { display: block; }
.fmt-label { font-family: var(--mono); font-size: 10px; text-transform: uppercase; letter-spacing: 4px; color: var(--text-4); margin-bottom: 12px; font-weight: 600; }
.fmt-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(100px, 1fr)); gap: 8px; }
.fmt-btn {
  padding: 13px 8px 11px; border: 1px solid var(--border-1); border-radius: var(--radius-sm);
  background: var(--bg-1); color: var(--text-3); cursor: pointer; transition: all 0.2s ease; text-align: center;
}
.fmt-btn:hover { border-color: var(--border-3); color: var(--text-2); background: var(--bg-2); }
.fmt-btn.picked { border-color: var(--accent); background: var(--accent-dim); color: var(--accent); box-shadow: 0 0 20px var(--accent-dim); }
.fmt-ext { font-family: var(--mono); font-size: 13px; font-weight: 700; letter-spacing: 1px; text-transform: uppercase; display: block; }
.fmt-desc { font-family: var(--sans); font-size: 9px; color: var(--text-4); margin-top: 3px; display: block; }
.fmt-btn.picked .fmt-desc { color: var(--accent); opacity: 0.6; }

.options-row {
  display: none; margin-top: 18px; gap: 16px; flex-wrap: wrap; background: var(--bg-2);
  border: 1px solid var(--border-1); border-radius: var(--radius-sm); padding: 18px 20px;
  transition: background 0.4s, border-color 0.4s;
}
.options-row.show { display: flex; }
.opt-group { display: flex; flex-direction: column; gap: 6px; flex: 1; min-width: 140px; }
.opt-label { font-family: var(--mono); font-size: 10px; color: var(--text-4); letter-spacing: 2px; text-transform: uppercase; }
.opt-range-row { display: flex; align-items: center; gap: 10px; }
.opt-range { flex: 1; height: 4px; -webkit-appearance: none; appearance: none; background: var(--bg-4); border-radius: 2px; outline: none; }
.opt-range::-webkit-slider-thumb { -webkit-appearance: none; width: 16px; height: 16px; border-radius: 50%; background: var(--accent); cursor: pointer; border: 2px solid var(--bg-0); }
.opt-range::-moz-range-thumb { width: 16px; height: 16px; border-radius: 50%; background: var(--accent); cursor: pointer; border: 2px solid var(--bg-0); }
.opt-range:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 2px; }
.opt-val { font-family: var(--mono); font-size: 13px; color: var(--accent); min-width: 40px; text-align: right; }

.go-btn {
  display: none; width: 100%; margin-top: 24px; padding: 20px; border: none;
  border-radius: var(--radius); font-family: var(--mono); font-size: 14px;
  font-weight: 700; letter-spacing: 5px; text-transform: uppercase; cursor: pointer;
  background: var(--accent); color: var(--btn-text); transition: all 0.25s ease;
}
.go-btn.show { display: block; }
.go-btn:hover { transform: translateY(-2px); box-shadow: 0 8px 36px var(--accent-glow); filter: brightness(1.1); }
.go-btn:active { transform: translateY(0); }
.go-btn:disabled { opacity: 0.4; cursor: wait; transform: none; filter: none; }

.prog { display: none; margin-top: 22px; }
.prog.show { display: block; }
.prog-track { height: 5px; background: var(--bg-3); border-radius: 3px; overflow: hidden; margin-bottom: 10px; }
.prog-fill { height: 100%; background: var(--accent); border-radius: 3px; width: 0%; transition: width 0.3s ease; }
.prog-label { font-family: var(--mono); font-size: 11px; color: var(--text-3); text-align: center; }

.result { display: none; margin-top: 24px; }
.result.show { display: block; animation: fadeIn 0.4s ease; }
.result-card {
  background: var(--bg-2); border: 1px solid var(--accent); border-radius: var(--radius);
  padding: 28px; text-align: center; box-shadow: 0 0 40px var(--accent-dim); transition: background 0.4s, border-color 0.4s;
}
.result-check { font-size: 36px; margin-bottom: 10px; display: block; }
.result-msg { font-size: 14px; color: var(--text-2); margin-bottom: 6px; }
.result-detail { font-family: var(--mono); font-size: 11px; color: var(--text-4); margin-bottom: 20px; }
.preview-box { margin-top: 14px; margin-bottom: 18px; }
.preview-box img { max-width: 100%; max-height: 260px; border-radius: var(--radius-sm); border: 1px solid var(--border-2); display: block; margin: 0 auto; }
.preview-box audio, .preview-box video { width: 100%; max-width: 520px; border-radius: var(--radius-sm); outline: none; display: block; margin: 0 auto; }
.dl-btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 14px 40px; border: none;
  border-radius: var(--radius-sm); background: var(--accent); font-family: var(--mono);
  font-size: 12px; font-weight: 700; letter-spacing: 3px; text-transform: uppercase;
  cursor: pointer; text-decoration: none; transition: all 0.2s; color: var(--btn-text);
}
.dl-btn:hover { transform: translateY(-1px); box-shadow: 0 4px 24px var(--accent-glow); }

/* ===== BATCH RESULT LIST ===== */
.batch-result { display: none; margin-top: 24px; }
.batch-result.show { display: block; animation: fadeIn 0.4s ease; }
.batch-result-header { text-align: center; margin-bottom: 16px; }
.batch-result-header .result-check { font-size: 36px; margin-bottom: 6px; display: block; }
.batch-result-summary { font-family: var(--mono); font-size: 13px; color: var(--text-2); }
.batch-result-items { display: flex; flex-direction: column; gap: 8px; }
.batch-result-item {
  display: flex; align-items: center; gap: 12px;
  background: var(--bg-2); border: 1px solid var(--border-1);
  border-radius: var(--radius-sm); padding: 14px 16px;
  transition: background 0.4s, border-color 0.4s;
}
.batch-result-item.success { border-color: var(--accent); }
.batch-result-item.failed { border-color: #dc2626; }
.batch-result-item-num {
  font-family: var(--mono); font-size: 11px; color: var(--text-4);
  width: 20px; text-align: center; flex-shrink: 0;
}
.batch-result-item-icon { font-size: 16px; flex-shrink: 0; }
.batch-result-item-meta { flex: 1; min-width: 0; }
.batch-result-item-name {
  font-weight: 600; font-size: 12px; white-space: nowrap;
  overflow: hidden; text-overflow: ellipsis;
}
.batch-result-item-detail {
  font-size: 10px; color: var(--text-3); font-family: var(--mono); margin-top: 2px;
}
.batch-result-item-detail.error-detail { color: #f87171; }
.batch-result-item .dl-btn {
  padding: 8px 16px; font-size: 10px; letter-spacing: 2px; flex-shrink: 0;
}
.batch-result-item-thumb {
  width: 48px; height: 48px; border-radius: var(--radius-xs, 6px);
  object-fit: cover; border: 1px solid var(--border-2); flex-shrink: 0;
}

/* ===== MERGE INFO BANNER ===== */
.merge-info {
  display: none; margin-top: 22px; padding: 16px 20px;
  background: var(--bg-2); border: 1px solid var(--border-1);
  border-radius: var(--radius-sm); text-align: center;
  font-family: var(--mono); font-size: 12px; color: var(--text-3);
  letter-spacing: 1px; transition: background 0.4s, border-color 0.4s;
}
.merge-info.show { display: block; }

.status-banner {
  display: none; margin-top: 16px; padding: 14px 20px; border-radius: var(--radius-sm);
  font-size: 13px; line-height: 1.6; border: 1px solid var(--border-2); background: var(--bg-2); color: var(--text-2);
}
.status-banner.show { display: block; }
.status-banner.error { border-color: #dc2626; background: rgba(220,38,38,0.08); color: #f87171; }
.status-banner.info { border-color: var(--accent); background: var(--accent-dim); }

.toast {
  position: fixed; bottom: 28px; left: 50%; transform: translateX(-50%) translateY(80px);
  padding: 13px 28px; background: #dc2626; color: #fff; border-radius: var(--radius-sm);
  font-size: 13px; font-weight: 500; z-index: 600; transition: transform 0.35s cubic-bezier(0.4,0,0.2,1);
  pointer-events: none; max-width: 90vw; text-align: center;
}
.toast.show { transform: translateX(-50%) translateY(0); }

.engine-status {
  display: none; align-items: center; gap: 8px; margin-bottom: 20px;
  padding: 12px 18px; background: var(--bg-2); border: 1px solid var(--border-1);
  border-radius: var(--radius-sm); font-size: 12px; color: var(--text-3); transition: background 0.4s, border-color 0.4s;
}
.engine-status.show { display: flex; }
.engine-dot { width: 8px; height: 8px; border-radius: 50%; flex-shrink: 0; }
.engine-dot.loading { background: #f59e0b; animation: pulse 1.2s infinite; }
.engine-dot.ready { background: var(--green); }
.engine-dot.failed { background: #dc2626; }

/* ===== MODE TOGGLE ===== */
.mode-toggle {
  display: flex; gap: 4px; background: var(--bg-1); border: 1px solid var(--border-1);
  border-radius: var(--radius-sm); padding: 4px; margin-bottom: 18px;
  transition: background 0.4s, border-color 0.4s;
}
.mode-btn {
  flex: 1; padding: 10px 14px; border: none; border-radius: var(--radius-xs, 6px);
  background: transparent; color: var(--text-3); font-family: var(--mono);
  font-size: 11px; font-weight: 600; letter-spacing: 1.5px; text-transform: uppercase;
  cursor: pointer; transition: all 0.2s ease;
}
.mode-btn:hover { color: var(--text-2); background: var(--bg-2); }
.mode-btn.active {
  background: var(--accent-dim); color: var(--text-1);
  box-shadow: 0 0 16px var(--accent-dim);
}

/* ===== MERGE FILE LIST ===== */
.merge-list { display: none; margin-top: 16px; }
.merge-list.show { display: block; }
.merge-list-label {
  font-family: var(--mono); font-size: 10px; text-transform: uppercase;
  letter-spacing: 3px; color: var(--text-4); margin-bottom: 10px; font-weight: 600;
}
.merge-items { display: flex; flex-direction: column; gap: 6px; }
.merge-item {
  display: flex; align-items: center; gap: 10px;
  background: var(--bg-2); border: 1px solid var(--border-1);
  border-radius: var(--radius-xs, 6px); padding: 10px 14px;
  transition: background 0.4s, border-color 0.4s;
}
.merge-item-num {
  font-family: var(--mono); font-size: 11px; color: var(--text-4);
  width: 20px; text-align: center; flex-shrink: 0;
}
.merge-item-icon { font-size: 16px; flex-shrink: 0; }
.merge-item-meta { flex: 1; min-width: 0; }
.merge-item-name {
  font-weight: 600; font-size: 12px; white-space: nowrap;
  overflow: hidden; text-overflow: ellipsis;
}
.merge-item-size {
  font-size: 10px; color: var(--text-3); font-family: var(--mono);
}
.merge-item-arrows {
  display: flex; flex-direction: column; gap: 2px; flex-shrink: 0;
}
.merge-item-arrows button {
  width: 22px; height: 18px; border: 1px solid var(--border-2);
  border-radius: 3px; background: none; color: var(--text-3);
  font-size: 10px; cursor: pointer; display: flex;
  align-items: center; justify-content: center; transition: all 0.15s;
}
.merge-item-arrows button:hover {
  border-color: var(--accent); color: var(--accent); background: var(--accent-dim);
}
.merge-item-arrows button:disabled { opacity: 0.2; cursor: default; }
.merge-item-arrows button:disabled:hover { border-color: var(--border-2); color: var(--text-3); background: none; }
.merge-item-x {
  width: 26px; height: 26px; border: 1px solid var(--border-2);
  border-radius: var(--radius-xs, 6px); background: none; color: var(--text-3);
  font-size: 14px; cursor: pointer; display: flex;
  align-items: center; justify-content: center; transition: all 0.2s; flex-shrink: 0;
}
.merge-item-x:hover { border-color: var(--coral); color: var(--coral); background: var(--coral-dim); }
.merge-add-btn {
  display: none; width: 100%; margin-top: 8px; padding: 10px;
  border: 1px dashed var(--border-2); border-radius: var(--radius-xs, 6px);
  background: none; color: var(--text-3); font-family: var(--mono);
  font-size: 11px; cursor: pointer; transition: all 0.2s;
}
.merge-add-btn.show { display: block; }
.merge-add-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-dim); }

.info-footer {
  margin-top: 52px; padding: 20px 24px; background: var(--bg-1);
  border: 1px solid var(--border-1); border-radius: var(--radius); transition: background 0.4s, border-color 0.4s;
}
.info-footer summary {
  font-family: var(--mono); font-size: 10px; color: var(--text-4); letter-spacing: 3px;
  text-transform: uppercase; cursor: pointer; list-style: none;
  display: flex; align-items: center; gap: 8px; user-select: none;
}
.info-footer summary::-webkit-details-marker { display: none; }
.info-footer summary::after { content: '\25B8'; transition: transform 0.2s; font-size: 10px; }
.info-footer[open] summary::after { transform: rotate(90deg); }
.info-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; margin-top: 18px; }
.info-grid h2 { font-size: 11px; color: var(--text-2); margin-bottom: 8px; font-weight: 600; }
.info-grid p { font-family: var(--mono); font-size: 10px; color: var(--text-4); line-height: 2; }

@media (max-width: 640px) {
  .header-inner { height: 56px; }
  .brand-name { font-size: 18px; letter-spacing: 2px; }
  .brand-sub { display: none; }
  .privacy-badge span:not(.privacy-dot) { display: none; }
  .privacy-badge { padding: 8px; }
  .tabs { flex-direction: column; gap: 4px; }
  .fmt-grid { grid-template-columns: repeat(auto-fill, minmax(82px, 1fr)); }
  .app { padding: 24px 14px 70px; }
  .dropzone { padding: 40px 18px; }
  .info-grid { grid-template-columns: 1fr; }
  .theme-toggle { }
  .mode-toggle { margin-bottom: 14px; }
  .mode-btn { padding: 8px 10px; font-size: 10px; letter-spacing: 1px; }
  .merge-item { padding: 8px 10px; gap: 8px; }
  .merge-item-name { font-size: 11px; }
  .batch-result-item { padding: 10px 12px; gap: 8px; }
  .batch-result-item-name { font-size: 11px; }
  .batch-result-item .dl-btn { padding: 6px 12px; font-size: 9px; }
  .batch-result-item-thumb { width: 36px; height: 36px; }
}

/* ===== SITE FOOTER ===== */
.site-footer{
  margin-top:60px;padding:48px 28px 36px;
  border-top:1px solid var(--border-1);
  background:var(--bg-0);color:var(--text-2);
  font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;
  font-size:14px;line-height:1.6;
}
.site-footer .footer-inner{max-width:1200px;margin:0 auto}
.site-footer .footer-grid{
  display:grid;grid-template-columns:2fr 1fr 1fr 1fr;
  gap:40px;margin-bottom:40px;
}
.site-footer .footer-brand{display:flex;align-items:center;gap:10px;margin-bottom:16px}
.site-footer .footer-brand svg{width:32px;height:32px;color:#a855f7;flex-shrink:0}
.site-footer .footer-brand-name{
  font-size:20px;font-weight:700;
  background:linear-gradient(90deg,#8B5CF6,#EC4899,#3B82F6);
  -webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text;
}
.site-footer .footer-desc{color:var(--text-3);margin-bottom:16px;max-width:360px}
.site-footer .footer-copy{font-size:12px;color:var(--text-3);opacity:.7}
.site-footer h2{font-weight:700;margin-bottom:16px;color:var(--text-1);font-size:15px}
.site-footer ul{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:10px}
.site-footer a{color:var(--text-2);text-decoration:none;transition:color .2s}
.site-footer a:hover{color:#a855f7}
.site-footer .footer-bottom{
  border-top:1px solid var(--border-1);
  padding-top:20px;text-align:center;
}
.site-footer .footer-bottom p{color:var(--text-3);font-size:13px;opacity:.7}
.site-footer .footer-bottom span{color:#a855f7}

@media(max-width:768px){
  .site-footer .footer-grid{grid-template-columns:1fr;gap:32px}
  .site-footer{padding:36px 16px 28px}
}

/* ===== SKIP LINK ===== */
.skip-link {
  position: absolute; top: -100%; left: 50%; transform: translateX(-50%);
  padding: 10px 20px; background: var(--accent); color: var(--btn-text);
  font-family: var(--mono); font-size: 13px; font-weight: 700;
  border-radius: var(--radius-sm); z-index: 1000; text-decoration: none;
  transition: top 0.2s;
}
.skip-link:focus { top: 12px; }

/* ===== FOCUS INDICATORS ===== */
.tab:focus-visible,
.mode-btn:focus-visible,
.fmt-btn:focus-visible,
.go-btn:focus-visible,
.dl-btn:focus-visible,
.back-link:focus-visible,
.merge-add-btn:focus-visible,
.file-bar-x:focus-visible,
.merge-item-x:focus-visible,
.theme-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.site-footer a:focus-visible {
  outline: 2px solid #a855f7;
  outline-offset: 2px;
}

/* ===== REDUCED MOTION ===== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ===== PRINT STYLES ===== */
@media print {
  body::before, body::after { display: none; }
  .app { padding: 20px 0; }
  .theme-toggle, .skip-link, .toast,
  .dropzone, .file-bar, .mode-toggle,
  .fmt-section, .options-row, .go-btn,
  .prog, .status-banner, .merge-list,
  .merge-info, .batch-result, .engine-status,
  .back-link { display: none !important; }
  .tabs { display: none; }
  .panel { display: block !important; }
  .panel .result { display: block !important; }
  .panel .result .dl-btn { display: none; }
  .info-footer { break-inside: avoid; border: 1px solid #ccc; }
  .site-footer { border-top: 1px solid #ccc; }
  .site-footer a { color: inherit; }
  .logo { -webkit-text-fill-color: #333; background: none; }
  * { color: #000 !important; background: #fff !important; box-shadow: none !important; border-color: #ccc !important; }
}