:root {
    --bg-0: #0a0c16; --bg-1: #101324;
    --panel: rgba(22, 26, 48, 0.72); --panel-solid: #161a30; --panel2: #1c2140;
    --border: #2a2f56; --border-soft: rgba(120, 130, 200, 0.18);
    --text: #eef0fb; --muted: #8891b8;
    --moon: #c9d3ff; --moon-dim: #8f9ad6; --cyan: #8fe3ff;
    --danger: #ff8f8f; --ok: #9be3b0; --warn: #ffcf7a;
    --radius-lg: 18px; --radius-md: 12px; --radius-sm: 8px;
    --ease: cubic-bezier(0.22, 1, 0.36, 1);
    box-sizing: border-box;
  }
  @media (prefers-color-scheme: light) {
    :root:not([data-theme="dark"]) {
      --bg-0: #eef0f8; --bg-1: #e3e7f4; --panel: rgba(255,255,255,0.75); --panel-solid: #ffffff;
      --panel2: #eef0fa; --border: #d7dcf0; --border-soft: rgba(80,90,160,0.16);
      --text: #14162a; --muted: #5a6088; --moon: #4a4fb8; --moon-dim: #6d72c4;
      --cyan: #0891b2; --danger: #c8384a; --ok: #147a4a; --warn: #b8730a;
    }
  }
  * { box-sizing: border-box; }
  html, body { height: 100%; margin: 0; }
  html { scroll-padding-top: env(safe-area-inset-top, 0px); -webkit-text-size-adjust: 100%; }
  body {
    background:
      radial-gradient(900px 500px at 12% -8%, rgba(143, 227, 255, 0.10), transparent 60%),
      radial-gradient(700px 500px at 100% 0%, rgba(201, 211, 255, 0.10), transparent 55%),
      linear-gradient(180deg, var(--bg-0), var(--bg-1));
    background-attachment: fixed;
    color: var(--text);
    font-family: 'Space Grotesk', -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    -webkit-font-smoothing: antialiased;
    min-height: 100%;
    padding-top: env(safe-area-inset-top, 0px);
    padding-bottom: env(safe-area-inset-bottom, 0px);
    overscroll-behavior-y: none;
  }
  /* Perf: on small/low-power devices, backdrop-filter blur is one of the
     heaviest paint costs on scroll. Drop it below 700px and let the solid
     fallback color (already in --panel's alpha) carry the look — this is
     the single biggest "less lag while scrolling on phones" win here. */
  @media (max-width: 700px), (prefers-reduced-motion: reduce) {
    .card, .panel { backdrop-filter: none; -webkit-backdrop-filter: none; background: var(--panel-solid); }
  }
  @media (max-width: 700px) {
    :root { --panel-solid: #14172c; }
  }
  @media (max-width: 700px) and (prefers-color-scheme: light) {
    :root:not([data-theme="dark"]) { --panel-solid: #f5f6fc; }
  }
  .mono { font-family: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

  .wrap { max-width: 1180px; margin: 0 auto; padding: clamp(16px, 4vw, 36px) clamp(14px, 4vw, 28px) 48px; animation: riseIn 0.5s var(--ease) both; }
  @keyframes riseIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
  @media (prefers-reduced-motion: reduce) { .wrap, * { animation: none !important; transition: none !important; } }

  header { display: flex; align-items: center; gap: 14px; margin-bottom: clamp(18px, 3vw, 28px); flex-wrap: wrap; }
  .moon-badge { position: relative; flex: none; width: 42px; height: 42px; border-radius: 50%; background: radial-gradient(circle at 32% 30%, #f4f6ff, var(--moon) 55%, #6a72c9 100%); box-shadow: 0 0 22px rgba(201, 211, 255, 0.35), inset -8px -6px 0 rgba(10, 12, 26, 0.55); }
  .moon-badge::after { content: ""; position: absolute; inset: -6px; border-radius: 50%; border: 1px solid var(--border-soft); animation: pulseRing 3.4s ease-in-out infinite; will-change: transform, opacity; }
  @keyframes pulseRing { 0%, 100% { opacity: 0.35; transform: scale(1); } 50% { opacity: 0.85; transform: scale(1.09); } }
  .title-row { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
  .title-block h1 { font-size: clamp(19px, 3.2vw, 24px); margin: 0; letter-spacing: -0.01em; font-weight: 700; }
  .brand-pill { font-size: 11px; padding: 3px 10px; border-radius: 999px; border: 1px solid var(--border); color: var(--moon-dim); background: var(--panel2); white-space: nowrap; }
  .sub { color: var(--muted); font-size: 13px; line-height: 1.55; max-width: 62ch; margin-top: 6px; }

  .card { background: var(--panel); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); border: 1px solid var(--border-soft); border-radius: var(--radius-lg); contain: layout style paint; }
  /* The "how it works" body is long and usually collapsed — skip rendering
     it until opened/scrolled to, so it doesn't cost anything up front. */
  .note-details .note-body { content-visibility: auto; contain-intrinsic-size: 0 420px; }

  .options { padding: 4px 0; margin-bottom: 14px; }
  .opt-group { padding: 14px 16px; }
  .opt-group + .opt-group { border-top: 1px solid var(--border-soft); }
  .opt-group-label { font-size: 11.5px; color: var(--muted); margin-bottom: 10px; font-weight: 600; }
  .opt-row { display: flex; flex-wrap: wrap; gap: 8px; }
  .opt { position: relative; display: flex; align-items: center; gap: 8px; background: var(--panel2); border: 1px solid var(--border); border-radius: 999px; padding: 8px 14px 8px 10px; font-size: 12.5px; font-weight: 500; cursor: pointer; user-select: none; min-height: 36px; touch-action: manipulation; transition: border-color 0.2s var(--ease), background 0.2s var(--ease), transform 0.15s var(--ease); }
  .opt:hover { transform: translateY(-1px); border-color: var(--border-soft); }
  .opt input { position: absolute; opacity: 0; width: 0; height: 0; }
  .switch { flex: none; width: 30px; height: 17px; border-radius: 999px; background: var(--border); position: relative; transition: background 0.25s var(--ease); }
  .switch::after { content: ""; position: absolute; top: 2px; left: 2px; width: 13px; height: 13px; border-radius: 50%; background: #cfd4ee; transition: transform 0.25s var(--ease), background 0.25s var(--ease); }
  .opt:has(input:checked) { border-color: var(--moon-dim); background: linear-gradient(180deg, rgba(143,227,255,0.10), rgba(201,211,255,0.06)); }
  .opt:has(input:checked) .switch { background: linear-gradient(90deg, var(--cyan), var(--moon)); }
  .opt:has(input:checked) .switch::after { transform: translateX(13px); background: #0b0d1a; }
  .opt.strong:has(input:checked) { border-color: var(--cyan); }
  .opt.warn:has(input:checked) { border-color: var(--warn); }
  .opt.warn:has(input:checked) .switch { background: linear-gradient(90deg, var(--warn), #ffb454); }
  .opt:focus-within { outline: 2px solid var(--cyan); outline-offset: 2px; }

  /* Custom dropdown (replaces native <select> chrome entirely) */
  .cdrop { position: relative; display: inline-flex; align-items: center; }
  .cdrop-btn { display: inline-flex; align-items: center; gap: 10px; background: var(--panel2); border: 1px solid var(--border); border-radius: 999px; padding: 8px 12px 8px 14px; font-family: 'Space Grotesk', sans-serif; font-size: 12.5px; font-weight: 600; color: var(--text); cursor: pointer; min-height: 36px; touch-action: manipulation; transition: border-color 0.2s var(--ease), background 0.2s var(--ease), transform 0.15s var(--ease); }
  .cdrop-btn:hover { transform: translateY(-1px); border-color: var(--moon-dim); }
  .cdrop-btn:focus-visible { outline: 2px solid var(--cyan); outline-offset: 2px; }
  .cdrop.open .cdrop-btn { border-color: var(--cyan); background: linear-gradient(180deg, rgba(143,227,255,0.10), rgba(201,211,255,0.06)); }
  .cdrop-label { white-space: nowrap; }
  .cdrop-arrow { flex: none; width: 8px; height: 8px; border-right: 2px solid var(--moon-dim); border-bottom: 2px solid var(--moon-dim); transform: rotate(45deg); margin-top: -4px; transition: transform 0.22s var(--ease), border-color 0.2s var(--ease), margin 0.22s var(--ease); }
  .cdrop.open .cdrop-arrow { transform: rotate(225deg); margin-top: 2px; border-color: var(--cyan); }
  .cdrop-list { position: fixed; min-width: 168px; z-index: 200; background: var(--panel-solid); border: 1px solid var(--border-soft); border-radius: var(--radius-md); box-shadow: 0 16px 36px rgba(4, 6, 16, 0.5); padding: 6px; max-height: min(280px, calc(100vh - 24px)); overflow-y: auto; -webkit-overflow-scrolling: touch; overscroll-behavior: contain; opacity: 0; visibility: hidden; pointer-events: none; transform: translateY(-6px) scale(0.98); transform-origin: top left; transition: opacity 0.16s var(--ease), transform 0.16s var(--ease), visibility 0.16s; }
  .cdrop-list.open { opacity: 1; visibility: visible; pointer-events: auto; transform: translateY(0) scale(1); }
  .cdrop-list, #logBody { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }
  .cdrop-list::-webkit-scrollbar { width: 8px; }
  .cdrop-list::-webkit-scrollbar-thumb { background: var(--border); border-radius: 8px; }
  .cdrop-opt { padding: 8px 10px; border-radius: 8px; font-size: 12.5px; font-family: 'Space Grotesk', sans-serif; color: var(--text); cursor: pointer; display: flex; align-items: center; justify-content: space-between; gap: 14px; white-space: nowrap; transition: background 0.15s var(--ease), color 0.15s var(--ease); }
  .cdrop-opt:hover, .cdrop-opt.active { background: var(--panel2); }
  .cdrop-opt:focus-visible { outline: 2px solid var(--cyan); outline-offset: -2px; }
  .cdrop-opt.selected { color: var(--cyan); font-weight: 600; }
  .cdrop-opt.selected::after { content: "\2713"; font-size: 11px; opacity: 0.9; }
  .cdrop-native { position: absolute; width: 0; height: 0; opacity: 0; pointer-events: none; border: 0; padding: 0; margin: 0; }
  .opt-inline-label { font-family: 'Space Grotesk', sans-serif; font-size: 12.5px; font-weight: 600; color: var(--text); }

  .grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
  @media (max-width: 780px) { .grid { grid-template-columns: 1fr; } }

  .panel { background: var(--panel); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); border: 1px solid var(--border-soft); border-radius: var(--radius-lg); overflow: hidden; display: flex; flex-direction: column; contain: layout style; transition: border-color 0.15s var(--ease), box-shadow 0.15s var(--ease); }
  .panel.dragover { border-color: var(--cyan); box-shadow: 0 0 0 2px rgba(143, 227, 255, 0.25) inset; }
  .panel-head { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 10px 14px; border-bottom: 1px solid var(--border-soft); font-size: 11.5px; color: var(--muted); text-transform: uppercase; letter-spacing: 0.08em; flex-wrap: wrap; }
  .head-actions { display: flex; align-items: center; gap: 10px; }
  .chip-btn { font-family: 'Space Grotesk', sans-serif; font-size: 11.5px; font-weight: 600; padding: 6px 12px; border-radius: 999px; cursor: pointer; border: 1px solid var(--border); background: var(--panel2); color: var(--text); transition: border-color 0.2s var(--ease), transform 0.15s var(--ease); text-transform: none; letter-spacing: 0; }
  .chip-btn:hover { transform: translateY(-1px); border-color: var(--moon-dim); }

  textarea { width: 100%; min-height: clamp(200px, 38vh, 360px); resize: vertical; background: transparent; color: var(--text); border: none; outline: none; padding: 14px; font-family: 'IBM Plex Mono', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; line-height: 1.55; }
  textarea::placeholder { color: var(--muted); opacity: 0.7; }
  textarea:focus { background: rgba(143, 227, 255, 0.03); }
  textarea, #logBody { scrollbar-width: thin; scrollbar-color: var(--border) transparent; }
  textarea::-webkit-scrollbar, #logBody::-webkit-scrollbar { width: 8px; }
  textarea::-webkit-scrollbar-thumb, #logBody::-webkit-scrollbar-thumb { background: var(--border); border-radius: 8px; }

  .btnrow { display: flex; gap: 9px; margin: 16px 0 6px; flex-wrap: wrap; align-items: center; }
  button { font-family: 'Space Grotesk', sans-serif; font-size: 13px; font-weight: 600; border: none; border-radius: 11px; padding: 12px 18px; cursor: pointer; min-height: 44px; touch-action: manipulation; transition: transform 0.15s var(--ease), box-shadow 0.2s var(--ease), opacity 0.15s var(--ease); }
  button:active { transform: scale(0.97); }
  .primary { background: linear-gradient(135deg, var(--cyan), var(--moon)); color: #0a0c16; box-shadow: 0 6px 22px rgba(143, 227, 255, 0.18); }
  .primary:hover { box-shadow: 0 8px 26px rgba(143, 227, 255, 0.28); transform: translateY(-1px); }
  .ghost { background: var(--panel2); color: var(--text); border: 1px solid var(--border); }
  .ghost:hover { border-color: var(--moon-dim); transform: translateY(-1px); }
  button:focus-visible { outline: 2px solid var(--cyan); outline-offset: 2px; }

  .status { font-size: 12.5px; padding: 10px 14px; border-radius: var(--radius-sm); margin: 4px 0 8px; display: none; border: 1px solid transparent; animation: slideFade 0.25s var(--ease); }
  @keyframes slideFade { from { opacity: 0; transform: translateY(-4px); } to { opacity: 1; transform: translateY(0); } }
  .status.ok { display: block; background: rgba(155, 227, 176, 0.10); color: var(--ok); border-color: rgba(155, 227, 176, 0.28); }
  .status.err { display: block; background: rgba(255, 143, 143, 0.10); color: var(--danger); border-color: rgba(255, 143, 143, 0.28); }

  .strength { display: flex; flex-direction: column; gap: 9px; padding: 14px 16px; margin: 4px 0 14px; font-size: 12.5px; color: var(--muted); }
  .strength-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; flex-wrap: wrap; }
  .strength-track { height: 6px; border-radius: 999px; background: var(--panel2); overflow: hidden; }
  .strength-fill { height: 100%; width: 0%; border-radius: 999px; background: linear-gradient(90deg, var(--cyan), var(--moon)); transition: width 0.35s var(--ease); }
  .strength .phases { font-size: 14px; letter-spacing: 3px; opacity: 0.85; }
  .strength b { color: var(--text); }

  .note-details { margin-top: 14px; }
  .note-details summary { list-style: none; cursor: pointer; padding: 14px 18px; font-size: 13px; font-weight: 600; display: flex; align-items: center; justify-content: space-between; gap: 10px; color: var(--text); }
  .note-details summary::-webkit-details-marker { display: none; }
  .note-details summary .chev { color: var(--muted); font-weight: 400; transition: transform 0.2s var(--ease); flex: none; }
  .note-details[open] summary .chev { transform: rotate(45deg); }
  .note-body { padding: 0 18px 18px; font-size: 12.5px; color: var(--muted); line-height: 1.65; }
  .note-body section + section { margin-top: 14px; padding-top: 14px; border-top: 1px solid var(--border-soft); }
  .note-body b { color: var(--text); }
  .note-body code { background: var(--panel2); border: 1px solid var(--border); border-radius: 4px; padding: 1px 5px; font-family: 'IBM Plex Mono', monospace; font-size: 11.5px; }

  .file-name-row { font-size: 12px; color: var(--muted); margin: -6px 0 10px; display: none; }
  .copied { color: var(--ok); font-size: 12px; }

  /* ---- Device-width scale (px), small phone → desktop ---- */

  /* Tablet / small laptop: tighten the two-column grid gap a touch */
  @media (max-width: 1024px) {
    .grid { gap: 10px; }
  }

  /* Large phones landscape / small tablets portrait (iPad mini portrait ~744px etc.) */
  @media (max-width: 780px) {
    .wrap { padding-bottom: 32px; }
  }

  /* Standard phones portrait (iPhone 14/15 ~390px, Pixel ~412px, Galaxy S ~360-412px) */
  @media (max-width: 600px) {
    .moon-badge { width: 36px; height: 36px; }
    header { gap: 11px; margin-bottom: 18px; }
    .panel-head { padding: 9px 12px; }
    .btnrow button { flex: 1 1 calc(50% - 5px); min-width: 0; }
    .opt-group { padding: 12px 14px; }
    .opt { flex: 1 1 auto; justify-content: center; }
    textarea { padding: 12px; font-size: 13.5px; min-height: clamp(160px, 32vh, 320px); }
  }

  /* Small phones (iPhone SE 375px, older Android 360px and below) */
  @media (max-width: 400px) {
    .wrap { padding-left: 12px; padding-right: 12px; }
    .moon-badge { width: 32px; height: 32px; }
    .title-block h1 { font-size: 18px; }
    .brand-pill { font-size: 10px; padding: 2px 8px; }
    .btnrow { gap: 7px; }
    .btnrow button { flex: 1 1 100%; padding: 11px 14px; }
    .opt-row { gap: 6px; }
    .opt { padding: 7px 12px 7px 9px; font-size: 12px; min-height: 34px; }
    .strength-top { font-size: 11.5px; }
    .strength .phases { font-size: 12px; letter-spacing: 2px; }
    .note-body { padding: 0 14px 14px; }
  }

  /* Very narrow devices (folded foldables, ~320px) */
  @media (max-width: 340px) {
    .wrap { padding-left: 10px; padding-right: 10px; }
    header { gap: 8px; }
    .title-row { gap: 6px; }
    .switch { width: 26px; height: 15px; }
    .switch::after { width: 11px; height: 11px; }
    .opt:has(input:checked) .switch::after { transform: translateX(11px); }
  }

  /* Short viewports (landscape phones, small windows): keep the input/output
     panels from forcing the page taller than the screen */
  @media (max-height: 480px) and (max-width: 900px) {
    textarea { min-height: clamp(120px, 30vh, 220px); }
    header { margin-bottom: 12px; }
  }

  /* Large desktop: cap line-length growth on the options row so pills don't
     stretch awkwardly on ultra-wide monitors */
  @media (min-width: 1400px) {
    .wrap { max-width: 1280px; }
  }