:root { --content-width: 860px; }

body {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px 16px 56px;
}

.header-container {
  width: 100%;
  max-width: var(--content-width);
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 20px;
}
.header-container h1 { font-size: 1.6rem; margin-right: auto; }

.panel {
  width: 100%;
  max-width: var(--content-width);
  margin-bottom: 14px;
  padding: 18px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
.panel-label {
  margin-bottom: 12px;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-faint);
}

.toolbar { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.toolbar-sep { width: 1px; height: 26px; background: var(--border); }

.btn { padding: 9px 14px; font-size: 0.9rem; white-space: nowrap; touch-action: manipulation; }
.btn.help-btn { padding: 8px 14px; font-size: 0.85rem; }

.btn.apply {
  color: #0e0e11;
  background: var(--primary);
  border-color: var(--primary);
}
.btn.apply:hover { color: #0e0e11; background: color-mix(in srgb, var(--primary) 85%, white); }

.btn.lock.active { color: var(--text); border-color: var(--extreme); background: color-mix(in srgb, var(--extreme) 18%, var(--surface-2)); }
.btn.undo:disabled { opacity: 0.35; cursor: not-allowed; }

.color-pick-wrap {
  position: relative;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color var(--ease), opacity var(--ease);
  touch-action: manipulation;
}
.color-pick-wrap:hover { border-color: var(--border-strong); }
.color-pick-wrap.hidden { display: none; }
.color-pick-wrap.dimmed { opacity: 0.4; }
.color-swatch { width: 20px; height: 20px; flex-shrink: 0; border-radius: 6px; border: 1px solid var(--border-strong); }
.color-pick-wrap span { font-size: 0.85rem; color: var(--text-dim); pointer-events: none; }
.color-pick-wrap input[type=color] { position: absolute; opacity: 0; width: 1px; height: 1px; pointer-events: none; }

select {
  padding: 9px 32px 9px 12px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-dim);
  cursor: pointer;
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%236c6c78' stroke-width='2.5'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 11px center;
}
select:hover { color: var(--text); border-color: var(--border-strong); }
select option { background: var(--surface); color: var(--text); font-size: 1.05rem; padding: 8px; }

.option-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}
.option-row.hidden { display: none; }
.option-label { width: 100%; font-size: 0.72rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--text-faint); }

.check {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 0.85rem;
  color: var(--text-dim);
  cursor: pointer;
  user-select: none;
}
.check input { width: 16px; height: 16px; accent-color: var(--primary); cursor: pointer; }

.grad-bar {
  flex: 1 1 140px;
  min-width: 120px;
  height: 34px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
}

.range-wrap { display: inline-flex; align-items: center; gap: 10px; font-size: 0.85rem; color: var(--text-dim); }
.range-wrap input[type=range] { width: 120px; accent-color: var(--primary); cursor: pointer; }
.range-wrap output { min-width: 1ch; font-variant-numeric: tabular-nums; color: var(--text); }

.toolbar-apply-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}
.toolbar-apply-row .btn.apply { flex: 1 1 200px; padding: 11px 24px; font-size: 1rem; }

textarea {
  width: 100%;
  min-height: 96px;
  padding: 14px;
  font-size: 1rem;
  line-height: 1.6;
  resize: vertical;
}
textarea.locked { cursor: text; user-select: text; -webkit-user-select: text; caret-color: transparent; }

.input-panel-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; }
.input-panel-header .panel-label { margin-bottom: 0; }
.input-meta { display: flex; align-items: center; gap: 14px; }
.lock-indicator { font-size: 0.72rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--extreme); opacity: 0; transition: opacity var(--ease); }
.lock-indicator.visible { opacity: 1; }
.char-count { font-size: 0.8rem; font-variant-numeric: tabular-nums; color: var(--text-faint); }
.char-count.full { color: var(--extreme); }

.bg-switch { display: inline-flex; border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }
.bg-btn {
  padding: 5px 12px;
  font: inherit;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-faint);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: color var(--ease), background var(--ease);
}
.bg-btn + .bg-btn { border-left: 1px solid var(--border); }
.bg-btn:hover { color: var(--text); }
.bg-btn.active { color: var(--text); background: var(--surface-2); }

.preview-box {
  min-height: 60px;
  padding: 14px;
  font-size: 1.2rem;
  line-height: 2;
  word-break: break-word;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: background var(--ease), color var(--ease);
}
.preview-box[data-bg="light"] { color: #1a1a1f; background: #f1f1f5; }

.output-wrap { position: relative; }
.output-box {
  min-height: 46px;
  padding: 13px 88px 13px 14px;
  font-family: ui-monospace, 'SF Mono', Menlo, Consolas, monospace;
  font-size: 0.85rem;
  color: var(--text-dim);
  white-space: pre-wrap;
  word-break: break-all;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color var(--ease);
}
.output-box:hover { border-color: var(--border-strong); }
.copy-btn {
  position: absolute;
  right: 8px;
  top: 50%;
  transform: translateY(-50%);
  padding: 7px 13px;
  font: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--primary);
  background: transparent;
  border: 1px solid color-mix(in srgb, var(--primary) 50%, transparent);
  border-radius: 8px;
  cursor: pointer;
  transition: background var(--ease);
}
.copy-btn:hover { background: color-mix(in srgb, var(--primary) 14%, transparent); }

.toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  max-width: calc(100% - 32px);
  padding: 10px 16px;
  font-size: 0.9rem;
  color: var(--text);
  background: var(--surface-2);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  transform: translate(-50%, 12px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.18s ease, transform 0.18s ease;
  z-index: 1000;
}
.toast.visible { opacity: 1; transform: translate(-50%, 0); }

.btn:focus-visible,
.bg-btn:focus-visible,
.copy-btn:focus-visible,
.output-box:focus-visible,
.close-sidebar-btn:focus-visible,
.color-pick-wrap:focus-within,
.check input:focus-visible,
.range-wrap input:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

.sidebar-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  z-index: 998;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.sidebar-overlay.active { opacity: 1; pointer-events: auto; }

.help-sidebar {
  position: fixed;
  top: 0;
  right: -100%;
  width: 100%;
  max-width: 360px;
  height: 100%;
  padding: 28px 22px;
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border-left: 1px solid var(--border);
  z-index: 999;
  transition: right 0.25s ease;
}
.help-sidebar.active { right: 0; }
.sidebar-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; padding-bottom: 14px; border-bottom: 1px solid var(--border); }
.sidebar-title { font-size: 1.1rem; font-weight: 700; }
.close-sidebar-btn { padding: 4px; font-size: 1.5rem; line-height: 1; color: var(--text-faint); background: none; border: none; cursor: pointer; }
.close-sidebar-btn:hover { color: var(--text); }
.sidebar-content { flex: 1; overflow-y: auto; }
.step-item { margin-bottom: 18px; }
.step-num { margin-bottom: 4px; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; color: var(--primary); }
.step-text { font-size: 0.92rem; line-height: 1.5; color: var(--text-dim); }
.step-text strong { color: var(--text); font-weight: 600; }

@media (max-width: 680px) {
  body { padding: 16px 12px 40px; }
  .header-container h1 { font-size: 1.3rem; }
  .panel { padding: 14px; }
  .toolbar { gap: 6px; }
  .btn { padding: 8px 12px; font-size: 0.85rem; }
  select { padding: 8px 28px 8px 11px; font-size: 0.85rem; }
  .grad-bar { flex-basis: 100%; }
}

@keyframes lnm-rise { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }

.header-container,
.panel {
  animation: lnm-rise 0.5s ease-out backwards;
  animation-delay: calc(var(--i, 0) * 0.06s);
}

.panel { transition: border-color var(--ease); }
.panel:focus-within { border-color: color-mix(in srgb, var(--primary) 45%, var(--border)); }

.btn { transition: color var(--ease), background var(--ease), border-color var(--ease), transform 0.12s ease, box-shadow 0.18s ease; }
.btn.apply:hover { box-shadow: 0 0 16px color-mix(in srgb, var(--primary) 35%, transparent); }

.help-sidebar.active .step-item { animation: lnm-rise 0.4s ease-out backwards; }
.help-sidebar.active .step-item:nth-child(1) { animation-delay: 0.10s; }
.help-sidebar.active .step-item:nth-child(2) { animation-delay: 0.15s; }
.help-sidebar.active .step-item:nth-child(3) { animation-delay: 0.20s; }
.help-sidebar.active .step-item:nth-child(4) { animation-delay: 0.25s; }
.help-sidebar.active .step-item:nth-child(5) { animation-delay: 0.30s; }
.help-sidebar.active .step-item:nth-child(6) { animation-delay: 0.35s; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}