/* ============================================================
   crisp-links · web companion stylesheet
   2026 minimalism + optimism
   ============================================================ */

/* -------------------------------------------------
   1. Design tokens
   ------------------------------------------------- */
:root {
  /* brand colors */
  --brand-coral:   #FF6B6B;
  --brand-amber:   #FFA500;
  --brand-yellow:  #FFD700;
  --brand-emerald: #10B981;
  --brand-cyan:    #06B6D4;
  --brand-indigo:  #4F46E5;
  --brand-violet:  #A855F7;
  --brand-claude:  #D97757;

  /* rainbow gradient — the signature motif */
  --grad-rainbow: linear-gradient(
    90deg,
    var(--brand-coral) 0%,
    var(--brand-amber) 16%,
    var(--brand-yellow) 33%,
    var(--brand-emerald) 50%,
    var(--brand-cyan) 66%,
    var(--brand-indigo) 83%,
    var(--brand-violet) 100%
  );

  --grad-warm: linear-gradient(135deg, var(--brand-coral), var(--brand-amber), var(--brand-violet));
  --grad-cool: linear-gradient(135deg, var(--brand-cyan), var(--brand-indigo), var(--brand-violet));

  /* spacing scale (4px grid) */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --space-9: 80px;
  --space-10: 96px;

  /* radii */
  --radius-xs: 6px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 28px;
  --radius-full: 999px;

  /* type */
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  /* motion */
  --ease-soft: cubic-bezier(0.32, 0.72, 0, 1);
  --transition-theme: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

/* light theme (default) */
body[data-app-theme="light"] {
  --bg: #fafbfc;
  --bg-elevated: #ffffff;
  --surface: #ffffff;
  --surface-2: #f6f8fa;
  --surface-3: #eef1f4;
  --border: #e1e4e8;
  --border-strong: #d0d7de;
  --fg: #1f2328;
  --fg-muted: #59636e;
  --fg-subtle: #818b97;
  --accent: #0969da;
  --accent-soft: color-mix(in oklab, #0969da 12%, transparent);
  --accent-ring: color-mix(in oklab, #0969da 28%, transparent);

  --shadow-sm: 0 1px 2px rgba(20, 27, 37, 0.04);
  --shadow-md: 0 4px 14px -2px rgba(20, 27, 37, 0.08), 0 1px 2px rgba(20, 27, 37, 0.04);
  --shadow-lg: 0 24px 60px -24px rgba(20, 27, 37, 0.18), 0 2px 6px rgba(20, 27, 37, 0.05);
  --shadow-card: 0 1px 2px rgba(20, 27, 37, 0.04), 0 28px 64px -32px rgba(20, 27, 37, 0.18);

  --header-bg: color-mix(in oklab, #ffffff 78%, transparent);
  --header-border: color-mix(in oklab, #1f2328 8%, transparent);

  --aurora-opacity: 0.55;
}

/* dark theme */
body[data-app-theme="dark"] {
  --bg: #0d1117;
  --bg-elevated: #161b22;
  --surface: #161b22;
  --surface-2: #1c232c;
  --surface-3: #232b36;
  --border: #30363d;
  --border-strong: #3d444d;
  --fg: #e6edf3;
  --fg-muted: #c9d1d9;
  --fg-subtle: #7d8590;
  --accent: #58a6ff;
  --accent-soft: color-mix(in oklab, #58a6ff 16%, transparent);
  --accent-ring: color-mix(in oklab, #58a6ff 36%, transparent);

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 14px -2px rgba(0, 0, 0, 0.4), 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 24px 60px -20px rgba(0, 0, 0, 0.6), 0 2px 6px rgba(0, 0, 0, 0.4);
  --shadow-card: 0 1px 2px rgba(0, 0, 0, 0.3), 0 28px 64px -32px rgba(0, 0, 0, 0.6);

  --header-bg: color-mix(in oklab, #0d1117 72%, transparent);
  --header-border: color-mix(in oklab, #e6edf3 10%, transparent);

  --aurora-opacity: 0.4;
}

/* -------------------------------------------------
   2. Base
   ------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-feature-settings: "cv11", "ss01", "ss03";
  font-size: 16px;
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  overflow-x: hidden;
  transition: var(--transition-theme);
}

button {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

input, textarea, select {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.15s var(--ease-soft), opacity 0.15s var(--ease-soft);
}
a:hover { opacity: 0.82; }

code {
  font-family: var(--font-mono);
  font-size: 0.875em;
  background: var(--surface-3);
  padding: 0.15em 0.45em;
  border-radius: var(--radius-xs);
  border: 1px solid var(--border);
  color: var(--fg);
}

.mono { font-family: var(--font-mono); font-feature-settings: "calt", "ss02"; }
.muted { color: var(--fg-subtle); font-weight: 400; }
.hidden { display: none !important; }

::selection {
  background: color-mix(in oklab, var(--accent) 28%, transparent);
  color: var(--fg);
}

/* focus rings */
:focus-visible {
  outline: 2px solid var(--accent-ring);
  outline-offset: 2px;
  border-radius: var(--radius-xs);
}

/* scrollbar (subtle) */
::-webkit-scrollbar { width: 12px; height: 12px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb {
  background: color-mix(in oklab, var(--fg-subtle) 26%, transparent);
  border-radius: var(--radius-full);
  border: 3px solid var(--bg);
}
::-webkit-scrollbar-thumb:hover {
  background: color-mix(in oklab, var(--fg-subtle) 44%, transparent);
}

/* -------------------------------------------------
   3. Aurora background
   ------------------------------------------------- */
.bg-aurora {
  position: fixed;
  inset: -10vh -10vw;
  z-index: -1;
  pointer-events: none;
  opacity: var(--aurora-opacity);
  filter: blur(80px) saturate(120%);
  background:
    radial-gradient(circle at 12% 14%, var(--brand-coral) 0%, transparent 32%),
    radial-gradient(circle at 84% 8%,  var(--brand-amber) 0%, transparent 30%),
    radial-gradient(circle at 92% 38%, var(--brand-yellow) 0%, transparent 28%),
    radial-gradient(circle at 76% 78%, var(--brand-emerald) 0%, transparent 32%),
    radial-gradient(circle at 18% 86%, var(--brand-cyan) 0%, transparent 34%),
    radial-gradient(circle at 6% 54%,  var(--brand-indigo) 0%, transparent 30%),
    radial-gradient(circle at 50% 50%, var(--brand-violet) 0%, transparent 28%);
  animation: aurora-drift 28s ease-in-out infinite alternate;
  transition: opacity 0.3s ease;
}

@keyframes aurora-drift {
  0%   { transform: translate3d(0, 0, 0) rotate(0deg) scale(1); }
  50%  { transform: translate3d(2%, -1%, 0) rotate(2deg) scale(1.04); }
  100% { transform: translate3d(-1%, 2%, 0) rotate(-1deg) scale(1.02); }
}

/* -------------------------------------------------
   4. Site header
   ------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  padding: var(--space-3) clamp(var(--space-5), 5vw, var(--space-9));
  background: var(--header-bg);
  backdrop-filter: saturate(160%) blur(18px);
  -webkit-backdrop-filter: saturate(160%) blur(18px);
  border-bottom: 1px solid var(--header-border);
  transition: var(--transition-theme);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--fg);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.brand:hover { opacity: 1; }

.brand-mark {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: var(--grad-rainbow);
  box-shadow:
    0 1px 2px rgba(0, 0, 0, 0.12),
    inset 0 0 0 1px rgba(255, 255, 255, 0.18);
  transform-origin: center;
  transition: transform 0.4s var(--ease-soft);
}
.brand:hover .brand-mark { transform: rotate(-8deg) scale(1.06); }

.brand-text {
  font-family: var(--font-mono);
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.site-nav {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
}

.nav-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--fg-muted);
  border: 1px solid transparent;
  transition: color 0.15s var(--ease-soft), background-color 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft);
}
.nav-link:hover {
  color: var(--fg);
  background: var(--surface-2);
  border-color: var(--border);
  opacity: 1;
}

.theme-switch {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface);
  position: relative;
  overflow: hidden;
  transition: var(--transition-theme), transform 0.15s var(--ease-soft);
}
.theme-switch:hover {
  border-color: var(--border-strong);
  transform: translateY(-1px);
}
.theme-switch-icon {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 18px;
  height: 18px;
  margin: -9px 0 0 -9px;
  color: var(--fg);
  transition: opacity 0.25s var(--ease-soft), transform 0.25s var(--ease-soft);
}
body[data-app-theme="light"] .theme-switch-icon[data-icon="light"] {
  opacity: 1; transform: translateY(0) rotate(0);
}
body[data-app-theme="light"] .theme-switch-icon[data-icon="dark"] {
  opacity: 0; transform: translateY(-80%) rotate(-30deg);
}
body[data-app-theme="dark"] .theme-switch-icon[data-icon="light"] {
  opacity: 0; transform: translateY(80%) rotate(30deg);
}
body[data-app-theme="dark"] .theme-switch-icon[data-icon="dark"] {
  opacity: 1; transform: translateY(0) rotate(0);
}

/* -------------------------------------------------
   5. App / hero
   ------------------------------------------------- */
.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: clamp(var(--space-6), 6vw, var(--space-10)) clamp(var(--space-4), 5vw, var(--space-9)) var(--space-10);
}

.hero {
  text-align: center;
  margin: clamp(var(--space-6), 5vw, var(--space-9)) auto var(--space-9);
  max-width: 880px;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--fg-subtle);
  margin: 0 0 var(--space-4);
}

.hero-title {
  font-size: clamp(2rem, 6vw, 4.5rem);
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: 1.04;
  margin: 0 0 var(--space-5);
  color: var(--fg);
  overflow-wrap: break-word;
}

.hero-grad {
  background: var(--grad-rainbow);
  background-size: 200% 100%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
  animation: gradient-shift 14s linear infinite;
  padding-right: 0.05em;
}

@keyframes gradient-shift {
  0%   { background-position: 0% 50%; }
  100% { background-position: 200% 50%; }
}

.hero-sub {
  font-size: clamp(1.0625rem, 1.6vw, 1.25rem);
  line-height: 1.55;
  color: var(--fg-muted);
  margin: 0 auto;
  max-width: 620px;
}

/* -------------------------------------------------
   6. Workspace (two-column)
   ------------------------------------------------- */
.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  gap: var(--space-5);
  align-items: start;
}

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--shadow-card);
  transition: var(--transition-theme);
  position: relative;
}

.panel-controls {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
  position: sticky;
  top: 80px;
}

.panel-output {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}

/* -------------------------------------------------
   7. Form fields
   ------------------------------------------------- */
.field {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.field-label {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-subtle);
}
.field-label.small {
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
}

.field-inline {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-3);
  align-items: center;
  padding-top: var(--space-2);
}

.text-input {
  width: 100%;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px var(--space-3);
  font-size: 0.9375rem;
  color: var(--fg);
  transition: border-color 0.15s var(--ease-soft), background-color 0.15s var(--ease-soft), box-shadow 0.15s var(--ease-soft);
}
.text-input:hover { border-color: var(--border-strong); }
.text-input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
  background: var(--surface);
}
.text-input::placeholder { color: var(--fg-subtle); }

input[type="number"].text-input {
  -moz-appearance: textfield;
  appearance: textfield;
}
input[type="number"].text-input::-webkit-outer-spin-button,
input[type="number"].text-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

/* range slider */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 24px;
  background: transparent;
  cursor: pointer;
}
input[type="range"]::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--surface-3);
  border: 1px solid var(--border);
}
input[type="range"]::-moz-range-track {
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--surface-3);
  border: 1px solid var(--border);
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 18px;
  height: 18px;
  border-radius: var(--radius-full);
  background: var(--surface);
  border: 2px solid var(--accent);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.18);
  margin-top: -7px;
  transition: transform 0.15s var(--ease-soft), box-shadow 0.15s var(--ease-soft);
}
input[type="range"]::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border-radius: var(--radius-full);
  background: var(--surface);
  border: 2px solid var(--accent);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.18);
  transition: transform 0.15s var(--ease-soft);
}
input[type="range"]:hover::-webkit-slider-thumb { transform: scale(1.1); }
input[type="range"]:hover::-moz-range-thumb { transform: scale(1.1); }
input[type="range"]:focus::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--accent-soft); }

.angle-val {
  font-size: 0.8125rem;
  color: var(--fg-muted);
  min-width: 3.25em;
  text-align: right;
}

/* -------------------------------------------------
   8. Segmented tabs (mode switcher)
   ------------------------------------------------- */
.seg-tabs {
  display: inline-flex;
  padding: 4px;
  gap: 2px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  width: 100%;
  overflow-x: auto;
  -ms-overflow-style: none;
  scrollbar-width: none;
}
.seg-tabs::-webkit-scrollbar { display: none; }

.seg-tab {
  flex: 1;
  white-space: nowrap;
  padding: var(--space-2) var(--space-4);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--fg-muted);
  border-radius: var(--radius-full);
  transition: color 0.15s var(--ease-soft), background-color 0.2s var(--ease-soft), box-shadow 0.2s var(--ease-soft);
}
.seg-tab:hover { color: var(--fg); }
.seg-tab.active {
  color: var(--fg);
  background: var(--surface);
  box-shadow: var(--shadow-sm), inset 0 0 0 1px var(--border);
  font-weight: 600;
}

/* -------------------------------------------------
   9. Solid color mode
   ------------------------------------------------- */
.color-row {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-3);
  align-items: center;
}

.color-swatch {
  position: relative;
  display: inline-block;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  cursor: pointer;
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  transition: transform 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft);
}
.color-swatch:hover {
  transform: translateY(-1px);
  border-color: var(--border-strong);
}
.color-swatch input[type="color"] {
  position: absolute;
  inset: -4px;
  width: calc(100% + 8px);
  height: calc(100% + 8px);
  opacity: 0;
  cursor: pointer;
  border: none;
  padding: 0;
}
.color-swatch-preview {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.18), inset 0 -10px 16px rgba(0, 0, 0, 0.08);
}

.quick-colors {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.quick-color {
  position: relative;
  width: 100%;
  aspect-ratio: 1;
  border-radius: var(--radius-full);
  border: 2px solid var(--surface);
  box-shadow:
    0 0 0 1px var(--border),
    inset 0 0 0 1px rgba(255, 255, 255, 0.2),
    var(--shadow-sm);
  cursor: pointer;
  transition: transform 0.15s var(--ease-soft), box-shadow 0.2s var(--ease-soft);
}
.quick-color:hover {
  transform: translateY(-2px) scale(1.05);
  box-shadow:
    0 0 0 1px var(--border-strong),
    inset 0 0 0 1px rgba(255, 255, 255, 0.25),
    var(--shadow-md);
}
.quick-color.selected {
  box-shadow:
    0 0 0 2px var(--surface),
    0 0 0 4px var(--accent),
    inset 0 0 0 1px rgba(255, 255, 255, 0.25);
  transform: translateY(-1px);
}

/* -------------------------------------------------
   10. Preset gradient grid
   ------------------------------------------------- */
.preset-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}
@container (min-width: 520px) {
  .preset-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}
@media (min-width: 1200px) {
  .preset-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

.preset-card {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: var(--space-2);
  padding: var(--space-3);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  text-align: left;
  transition: transform 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft), box-shadow 0.2s var(--ease-soft), background-color 0.15s var(--ease-soft);
}
.preset-card:hover {
  transform: translateY(-2px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
  background: var(--surface);
}
.preset-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft), var(--shadow-md);
  background: var(--surface);
}

.preset-swatch {
  display: block;
  height: 36px;
  border-radius: var(--radius-sm);
  box-shadow:
    inset 0 0 0 1px rgba(255, 255, 255, 0.15),
    inset 0 -6px 10px rgba(0, 0, 0, 0.06);
}

.preset-name {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--fg);
  letter-spacing: -0.005em;
  padding: 0 var(--space-1);
}

/* -------------------------------------------------
   11. Custom gradient stops
   ------------------------------------------------- */
.stops-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.stop-row {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-2);
  align-items: center;
  padding: var(--space-2);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  transition: var(--transition-theme);
}

.stop-row .color-swatch {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-xs);
}

.stop-row .text-input {
  padding: 6px var(--space-2);
  font-size: 0.875rem;
}

.stop-remove {
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-xs);
  color: var(--fg-subtle);
  background: transparent;
  font-size: 18px;
  line-height: 1;
  transition: background-color 0.15s var(--ease-soft), color 0.15s var(--ease-soft);
}
.stop-remove:hover {
  background: color-mix(in oklab, var(--brand-coral) 12%, transparent);
  color: var(--brand-coral);
}

.btn-ghost {
  align-self: flex-start;
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  margin-top: var(--space-2);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--fg-muted);
  background: transparent;
  border: 1px dashed var(--border-strong);
  border-radius: var(--radius-sm);
  transition: color 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft), background-color 0.15s var(--ease-soft);
}
.btn-ghost:hover {
  color: var(--accent);
  border-color: var(--accent);
  border-style: solid;
  background: var(--accent-soft);
}

/* -------------------------------------------------
   12. Advanced details disclosure
   ------------------------------------------------- */
.advanced {
  border-top: 1px solid var(--border);
  padding-top: var(--space-4);
  margin-top: var(--space-1);
}

.advanced summary {
  list-style: none;
  cursor: pointer;
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-subtle);
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  transition: color 0.15s var(--ease-soft);
}
.advanced summary::-webkit-details-marker { display: none; }
.advanced summary::before {
  content: "";
  width: 10px;
  height: 10px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(-45deg);
  transition: transform 0.2s var(--ease-soft);
  margin-bottom: 2px;
}
.advanced[open] summary::before { transform: rotate(45deg); margin-bottom: 0; margin-top: 2px; }
.advanced summary:hover { color: var(--fg); }

.advanced-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(96px, 1fr));
  gap: var(--space-3);
  margin-top: var(--space-4);
}

/* -------------------------------------------------
   13. Preview shell (output panel top)
   ------------------------------------------------- */
.preview-shell {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.preview-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.preview-label,
.output-label {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--fg-subtle);
}

.theme-pills {
  display: inline-flex;
  padding: 3px;
  gap: 2px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
}

.theme-pill {
  padding: 4px var(--space-3);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--fg-muted);
  border-radius: var(--radius-full);
  transition: color 0.15s var(--ease-soft), background-color 0.2s var(--ease-soft), box-shadow 0.2s var(--ease-soft);
}
.theme-pill:hover { color: var(--fg); }
.theme-pill.active {
  color: var(--fg);
  background: var(--surface);
  box-shadow: var(--shadow-sm), inset 0 0 0 1px var(--border);
  font-weight: 600;
}

/* Preview canvas — INDEPENDENT theme via [data-theme] */
.preview-canvas {
  position: relative;
  border-radius: var(--radius-md);
  border: 1px solid;
  padding: var(--space-5) var(--space-5) var(--space-6);
  min-height: 140px;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

.preview-canvas[data-theme="light"] {
  background: #ffffff;
  border-color: #e1e4e8;
  color: #1f2328;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6), 0 1px 2px rgba(20, 27, 37, 0.04);
}

.preview-canvas[data-theme="dark"] {
  background: #0d1117;
  border-color: #30363d;
  color: #e6edf3;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.04), 0 1px 2px rgba(0, 0, 0, 0.3);
}

.preview-filename {
  margin: 0 0 var(--space-4);
  font-size: 0.8125rem;
  color: inherit;
  opacity: 0.55;
  letter-spacing: -0.005em;
}

.preview-row {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-height: 40px;
  flex-wrap: wrap;
}

.preview-icon {
  font-size: 22px;
  line-height: 1;
  flex-shrink: 0;
  width: 26px;
  text-align: center;
}

.preview-link {
  display: inline-flex;
  text-decoration: none;
  border: 0;
  flex-shrink: 0;
}
.preview-link img {
  display: block;
  max-width: 100%;
  height: auto;
}

.preview-desc {
  font-size: 0.9375rem;
  opacity: 0.7;
  flex: 1;
  min-width: 200px;
  letter-spacing: -0.005em;
}

.preview-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.meta-pill {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 4px var(--space-2);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  color: var(--fg-muted);
}

/* -------------------------------------------------
   14. Output blocks (markdown + svg)
   ------------------------------------------------- */
.output-block {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.output-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.code-block {
  margin: 0;
  padding: var(--space-4);
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.04);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.55;
  color: var(--fg);
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
  max-height: 240px;
  transition: var(--transition-theme);
}
.code-block code {
  background: transparent;
  border: 0;
  padding: 0;
  font-size: inherit;
  color: inherit;
}

/* -------------------------------------------------
   15. Buttons (copy / download / primary)
   ------------------------------------------------- */
.btn-copy {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 6px var(--space-3);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--fg-muted);
  transition: color 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft), background-color 0.15s var(--ease-soft), transform 0.15s var(--ease-soft);
}
.btn-copy svg { flex-shrink: 0; opacity: 0.85; }
.btn-copy:hover {
  color: var(--fg);
  border-color: var(--border-strong);
  background: var(--surface-2);
  transform: translateY(-1px);
}
.btn-copy:active { transform: translateY(0); }
.btn-copy.copied {
  color: var(--brand-emerald);
  border-color: color-mix(in oklab, var(--brand-emerald) 40%, var(--border));
  background: color-mix(in oklab, var(--brand-emerald) 8%, var(--surface));
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  margin-top: var(--space-3);
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: -0.005em;
  color: #ffffff;
  background: var(--grad-rainbow);
  background-size: 200% 100%;
  background-position: 0% 50%;
  border-radius: var(--radius-md);
  border: 0;
  box-shadow:
    0 1px 2px rgba(0, 0, 0, 0.12),
    0 8px 24px -8px color-mix(in oklab, var(--brand-violet) 60%, transparent),
    inset 0 1px 0 rgba(255, 255, 255, 0.25);
  cursor: pointer;
  transition: background-position 0.6s var(--ease-soft), transform 0.15s var(--ease-soft), box-shadow 0.2s var(--ease-soft);
}
.btn-primary:hover {
  background-position: 100% 50%;
  transform: translateY(-2px);
  box-shadow:
    0 1px 2px rgba(0, 0, 0, 0.14),
    0 16px 32px -10px color-mix(in oklab, var(--brand-violet) 70%, transparent),
    inset 0 1px 0 rgba(255, 255, 255, 0.3);
}
.btn-primary:active { transform: translateY(0); }

/* -------------------------------------------------
   16. "How to use" section
   ------------------------------------------------- */
.how {
  margin-top: var(--space-10);
}

.how-title,
.batch-head h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.15;
  margin: 0 0 var(--space-5);
  color: var(--fg);
}

.how-steps {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-4);
}

.how-steps li {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  gap: var(--space-4);
  align-items: flex-start;
  box-shadow: var(--shadow-sm);
  transition: var(--transition-theme), transform 0.15s var(--ease-soft);
}
.how-steps li:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.how-steps li > div { flex: 1; min-width: 0; }

.how-steps strong {
  display: block;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--fg);
  margin-bottom: var(--space-1);
}

.how-steps p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.55;
  color: var(--fg-muted);
}

.how-steps code {
  font-size: 0.8125rem;
}

.step-num {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  font-weight: 600;
  color: #ffffff;
  background: var(--grad-rainbow);
  background-size: 200% 100%;
  border-radius: var(--radius-sm);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.25), 0 1px 2px rgba(0, 0, 0, 0.12);
}

.how-steps li:nth-child(1) .step-num { background-position: 0% 50%; }
.how-steps li:nth-child(2) .step-num { background-position: 50% 50%; }
.how-steps li:nth-child(3) .step-num { background-position: 100% 50%; }

/* -------------------------------------------------
   17. Batch section
   ------------------------------------------------- */
.batch-section {
  margin-top: var(--space-10);
}

.batch-head {
  margin-bottom: var(--space-5);
}

.batch-head p {
  margin: 0;
  font-size: 1rem;
  color: var(--fg-muted);
  max-width: 64ch;
}

.batch-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: var(--space-5);
  align-items: start;
}

.batch-grid > div {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.batch-textarea {
  width: 100%;
  min-height: 200px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--fg);
  resize: vertical;
  transition: border-color 0.15s var(--ease-soft), box-shadow 0.15s var(--ease-soft);
}
.batch-textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.batch-results {
  min-height: 200px;
  max-height: 480px;
  overflow-y: auto;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-4);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.batch-placeholder {
  margin: auto;
  color: var(--fg-subtle);
  font-size: 0.875rem;
  text-align: center;
}

.batch-result-item {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: var(--space-3);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.batch-result-item .batch-preview {
  display: flex;
  align-items: center;
  min-height: 28px;
}
.batch-result-item .batch-preview img {
  max-width: 100%;
  height: auto;
  display: block;
}
.batch-result-item .batch-md {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--fg-muted);
  word-break: break-all;
  padding: var(--space-2);
  background: var(--surface-2);
  border-radius: var(--radius-xs);
  border: 1px solid var(--border);
}

/* -------------------------------------------------
   18. Footer
   ------------------------------------------------- */
.site-footer {
  margin-top: var(--space-10);
  padding: var(--space-7) clamp(var(--space-4), 5vw, var(--space-9));
  border-top: 1px solid var(--border);
  background: color-mix(in oklab, var(--surface) 60%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  text-align: center;
}

.footer-text {
  margin: 0;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--fg-subtle);
}

.footer-text a {
  color: var(--fg-muted);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in oklab, var(--fg-subtle) 40%, transparent);
  padding-bottom: 1px;
  transition: color 0.15s var(--ease-soft), border-color 0.15s var(--ease-soft);
}
.footer-text a:hover {
  color: var(--fg);
  border-bottom-color: var(--fg);
  opacity: 1;
}

.footer-grad {
  background: var(--grad-rainbow);
  background-size: 200% 100%;
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
  font-weight: 700;
  animation: gradient-shift 14s linear infinite;
}

/* -------------------------------------------------
   19. Toast
   ------------------------------------------------- */
.toast {
  position: fixed;
  right: var(--space-5);
  bottom: var(--space-5);
  z-index: 100;
  padding: var(--space-3) var(--space-5);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  color: var(--fg);
  font-size: 0.875rem;
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  transform: translateY(8px);
  pointer-events: none;
  transition: opacity 0.2s var(--ease-soft), transform 0.25s var(--ease-soft);
}
.toast.visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.toast::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: var(--radius-full);
  background: var(--brand-emerald);
  margin-right: var(--space-2);
  vertical-align: middle;
  box-shadow: 0 0 0 3px color-mix(in oklab, var(--brand-emerald) 22%, transparent);
}

/* -------------------------------------------------
   20. Responsive
   ------------------------------------------------- */
@media (max-width: 1024px) {
  .panel-controls { position: static; }
}

@media (max-width: 900px) {
  .workspace {
    grid-template-columns: minmax(0, 1fr);
  }
  .batch-grid {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (max-width: 720px) {
  .site-header {
    padding: var(--space-3) var(--space-4);
  }
  .nav-link span { display: none; }
  .nav-link { padding: var(--space-2); }

  .app {
    padding: var(--space-5) var(--space-4) var(--space-8);
  }

  .panel {
    padding: var(--space-4);
    border-radius: var(--radius-lg);
  }

  .hero {
    margin: var(--space-6) auto var(--space-7);
  }

  .quick-colors {
    grid-template-columns: repeat(8, 1fr);
    gap: 6px;
  }

  .preset-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .how, .batch-section {
    margin-top: var(--space-8);
  }

  .toast {
    left: var(--space-4);
    right: var(--space-4);
    bottom: var(--space-4);
    text-align: center;
  }
}

@media (max-width: 480px) {
  .seg-tabs {
    font-size: 0.75rem;
  }
  .seg-tab {
    padding: 6px var(--space-3);
  }
  .quick-colors {
    grid-template-columns: repeat(4, 1fr);
  }
  .preview-desc {
    min-width: 0;
    width: 100%;
  }
}

/* -------------------------------------------------
   21. Accessibility — reduced motion
   ------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  .bg-aurora { animation: none; }
  .hero-grad { animation: none; }
}

/* -------------------------------------------------
   22. Print
   ------------------------------------------------- */
@media print {
  .bg-aurora,
  .site-header,
  .site-footer,
  .toast,
  .btn-primary,
  .btn-copy { display: none; }
  body { background: #ffffff; color: #000000; }
  .panel { box-shadow: none; border-color: #ccc; }
}