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

/* ── Light tokens ───────────────────────────────────────────────────────────── */
:root {
  --bg:           #F5F5F7;
  --surface:      #FFFFFF;
  --border:       #E8E8ED;
  --border-light: #F0F0F5;
  --text:         #1D1D1F;
  --text-2:       #3D3D3F;
  --muted:        #6E6E73;
  --faint:        #AEAEB2;
  --accent:       #0071E3;
  --accent-bg:    rgba(0,113,227,.08);
  --accent-border:rgba(0,113,227,.25);
  --accent-side:  rgba(0,113,227,.10);
  --nav-bg:       rgba(255,255,255,.88);
  --code-bg:      #F5F5F7;
  --shadow:       rgba(0,0,0,.06);
  --radius-s:     6px;
  --radius-m:     10px;
  --radius-l:     12px;
  --nav-h:        52px;
  --sidebar-w:    240px;
  --font:         -apple-system, BlinkMacSystemFont, 'Inter', 'Helvetica Neue', sans-serif;
  --font-mono:    'SF Mono', 'Fira Code', 'Cascadia Code', monospace;
}

/* ── Dark tokens ────────────────────────────────────────────────────────────── */
[data-theme="dark"] {
  --bg:           #000000;
  --surface:      #1C1C1E;
  --border:       #38383A;
  --border-light: #2C2C2E;
  --text:         #F2F2F7;
  --text-2:       #D1D1D6;
  --muted:        #8E8E93;
  --faint:        #48484A;
  --accent:       #0A84FF;
  --accent-bg:    rgba(10,132,255,.12);
  --accent-border:rgba(10,132,255,.30);
  --accent-side:  rgba(10,132,255,.15);
  --nav-bg:       rgba(28,28,30,.90);
  --code-bg:      #2C2C2E;
  --shadow:       rgba(0,0,0,.30);
}

/* Auto dark via OS preference (unless user explicitly set light) */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg:           #000000;
    --surface:      #1C1C1E;
    --border:       #38383A;
    --border-light: #2C2C2E;
    --text:         #F2F2F7;
    --text-2:       #D1D1D6;
    --muted:        #8E8E93;
    --faint:        #48484A;
    --accent:       #0A84FF;
    --accent-bg:    rgba(10,132,255,.12);
    --accent-border:rgba(10,132,255,.30);
    --accent-side:  rgba(10,132,255,.15);
    --nav-bg:       rgba(28,28,30,.90);
    --code-bg:      #2C2C2E;
    --shadow:       rgba(0,0,0,.30);
  }
}

/* ── Base ───────────────────────────────────────────────────────────────────── */
html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  color-scheme: light dark;
}
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  transition: background .2s, color .2s;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 3px; }

/* ── Navbar ─────────────────────────────────────────────────────────────────── */
.nav {
  position: sticky; top: 0; z-index: 100;
  height: var(--nav-h);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 40px;
  background: var(--nav-bg);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border);
}

.nav-logo {
  display: flex; align-items: center; gap: 8px;
  font-size: 15px; font-weight: 600; color: var(--text);
  text-decoration: none; flex-shrink: 0;
}
.nav-logo:hover { text-decoration: none; }
.nav-logo svg { width: 20px; height: 20px; flex-shrink: 0; }

.nav-links {
  display: flex; align-items: center; gap: 28px;
  list-style: none;
}
.nav-links a {
  font-size: 14px; color: var(--text); text-decoration: none;
  transition: color .15s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--accent); }
.nav-links a:hover { text-decoration: none; }

.nav-right {
  display: flex; align-items: center; gap: 8px;
}

.nav-search {
  display: flex; align-items: center; gap: 6px;
  padding: 6px 12px;
  background: var(--border);
  border-radius: var(--radius-s);
  font-size: 13px; color: var(--muted);
  cursor: pointer; border: none; outline: none;
  font-family: var(--font);
  transition: background .15s;
}
.nav-search:hover { background: var(--faint); }
.nav-search svg { width: 14px; height: 14px; flex-shrink: 0; }

/* Theme toggle button */
.theme-toggle {
  width: 34px; height: 34px;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--border);
  border-radius: var(--radius-s);
  background: transparent;
  cursor: pointer; color: var(--muted);
  transition: background .15s, color .15s;
  flex-shrink: 0;
}
.theme-toggle:hover { background: var(--border); color: var(--text); }
.theme-toggle svg { width: 16px; height: 16px; }
.theme-toggle .icon-sun  { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun  { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .icon-sun  { display: block; }
  :root:not([data-theme="light"]) .theme-toggle .icon-moon { display: none; }
}

/* ── Layout ─────────────────────────────────────────────────────────────────── */
.shell {
  display: flex;
  min-height: calc(100vh - var(--nav-h));
}

.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  padding: 28px 16px;
  background: var(--surface);
  border-right: 1px solid var(--border);
  position: sticky;
  top: var(--nav-h);
  height: calc(100vh - var(--nav-h));
  overflow-y: auto;
}

.sidebar-label {
  font-size: 11px; font-weight: 600;
  letter-spacing: 0.8px; text-transform: uppercase;
  color: var(--faint);
  padding: 0 8px; margin-bottom: 6px;
}

.sidebar-item {
  display: flex; align-items: center; gap: 8px;
  padding: 7px 12px;
  border-radius: var(--radius-s);
  font-size: 13px; color: var(--muted);
  text-decoration: none;
  transition: background .12s, color .12s;
}
.sidebar-item svg { width: 15px; height: 15px; flex-shrink: 0; color: currentColor; opacity: .7; }
.sidebar-item:hover { background: var(--bg); color: var(--text); text-decoration: none; }
.sidebar-item.active {
  background: var(--accent-side);
  color: var(--accent);
  font-weight: 500;
}
.sidebar-item.active svg { opacity: 1; }
.sidebar-divider { height: 1px; background: var(--border); margin: 10px 0; }

/* ── Main ───────────────────────────────────────────────────────────────────── */
.main {
  flex: 1; min-width: 0;
  background: var(--surface);
  padding: 36px 56px;
}

/* ── Breadcrumb ─────────────────────────────────────────────────────────────── */
.breadcrumb {
  display: flex; align-items: center; gap: 6px; flex-wrap: wrap;
  font-size: 13px; margin-bottom: 20px;
}
.breadcrumb a { color: var(--accent); }
.breadcrumb .sep { color: var(--faint); }
.breadcrumb .current { color: var(--muted); }

/* ── Page header ────────────────────────────────────────────────────────────── */
.page-header { margin-bottom: 20px; }
.page-title {
  font-size: 28px; font-weight: 700;
  line-height: 1.2; letter-spacing: -0.4px; margin-bottom: 8px;
}
.page-subtitle { font-size: 15px; color: var(--muted); line-height: 1.5; }
.page-divider  { height: 1px; background: var(--border); margin: 20px 0; }

/* ── Article meta ───────────────────────────────────────────────────────────── */
.art-meta {
  display: flex; align-items: center; gap: 10px;
  font-size: 12px; color: var(--faint); flex-wrap: wrap;
  margin-bottom: 20px;
}
.art-meta .sep { color: var(--faint); }
.art-tag {
  display: inline-block; padding: 2px 8px;
  border-radius: 4px;
  background: var(--accent-bg); color: var(--accent);
  font-size: 11px; font-weight: 500;
  border: 1px solid var(--accent-border);
}

/* ── Article list ───────────────────────────────────────────────────────────── */
.art-list { list-style: none; }
.art-list-item {
  display: flex; align-items: center; gap: 14px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border-light);
  text-decoration: none; color: inherit;
  transition: color .12s;
}
.art-list-item:last-child { border-bottom: none; }
.art-list-item:hover { color: var(--accent); text-decoration: none; }
.art-list-item:hover .art-list-arrow { color: var(--accent); }

.art-list-icon {
  width: 36px; height: 36px; flex-shrink: 0;
  border-radius: var(--radius-s);
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  display: flex; align-items: center; justify-content: center;
}
.art-list-icon svg { width: 17px; height: 17px; color: var(--accent); }
.art-list-body { flex: 1; min-width: 0; }
.art-list-title { font-size: 14px; font-weight: 500; margin-bottom: 2px; }
.art-list-desc  { font-size: 13px; color: var(--muted); }
.art-list-arrow { color: var(--faint); transition: color .12s; flex-shrink: 0; }
.art-list-arrow svg { width: 15px; height: 15px; display: block; }

/* ── Article body ───────────────────────────────────────────────────────────── */
.art-body {
  font-family: 'Lora', Georgia, 'Times New Roman', serif;
  font-size: 17px;
  line-height: 1.82;
  color: var(--text-2);
}

/* Headings stay sans-serif for contrast */
.art-body h1, .art-body h2, .art-body h3, .art-body h4 {
  font-family: var(--font);
  color: var(--text);
}
.art-body h1 {
  font-size: 32px; font-weight: 700;
  letter-spacing: -0.6px; line-height: 1.15;
  margin: 0 0 20px;
}
.art-body h2 {
  font-size: 21px; font-weight: 600;
  letter-spacing: -0.3px; line-height: 1.3;
  margin: 44px 0 14px;
  padding-top: 4px;
}
.art-body h3 {
  font-size: 16.5px; font-weight: 600;
  line-height: 1.4; margin: 28px 0 8px;
}
.art-body h4 {
  font-size: 14px; font-weight: 600;
  margin: 16px 0 6px; color: var(--muted);
}
.art-body p {
  margin-bottom: 18px;
}
.art-body ul, .art-body ol {
  margin: 0 0 18px 24px;
}
.art-body li {
  line-height: 1.75; margin-bottom: 6px;
}
.art-body strong { font-weight: 600; color: var(--text); }
.art-body em { font-style: italic; }
.art-body a { color: var(--accent); }

/* Inline code */
.art-body :not(pre) > code {
  font-family: var(--font-mono);
  font-size: 13.5px;
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--text);
}

/* Code blocks — always dark (terminal style) */
.art-body pre {
  position: relative;
  background: #1e1e2e;
  border: 1px solid #313244;
  border-radius: var(--radius-m);
  padding: 16px 20px;
  padding-right: 52px; /* room for copy button */
  overflow-x: auto;
  margin-bottom: 18px;
  font-size: 13.5px;
  line-height: 1.7;
}
.art-body pre code {
  background: none; border: none; padding: 0;
  font-family: var(--font-mono);
  color: #cdd6f4; /* Catppuccin Mocha text — high contrast on dark bg */
}

/* Copy button */
.pre-copy-btn {
  position: absolute;
  top: 10px; right: 10px;
  display: flex; align-items: center; gap: 5px;
  padding: 5px 10px;
  background: rgba(205,214,244,.1);
  border: 1px solid rgba(205,214,244,.18);
  border-radius: 6px;
  color: #a6adc8;
  font: 500 11.5px/1 var(--font);
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s, background .15s, color .15s;
  white-space: nowrap;
}
.pre-copy-btn svg { width: 13px; height: 13px; flex-shrink: 0; }
.art-body pre:hover .pre-copy-btn { opacity: 1; }
.pre-copy-btn:hover { background: rgba(205,214,244,.2); color: #cdd6f4; }
.pre-copy-btn.copied {
  color: #a6e3a1;
  border-color: rgba(166,227,161,.3);
  background: rgba(166,227,161,.1);
}

/* Tables */
.art-body table {
  width: 100%; border-collapse: collapse;
  margin-bottom: 16px; font-size: 14px;
}
.art-body th {
  text-align: left; padding: 8px 12px;
  background: var(--bg); border: 1px solid var(--border);
  font-weight: 600; color: var(--text);
}
.art-body td {
  padding: 8px 12px;
  border: 1px solid var(--border);
  color: var(--text-2); vertical-align: top;
}
.art-body tr:nth-child(even) td { background: var(--bg); }

/* Blockquotes (Tip/Note callouts) */
.art-body blockquote {
  display: flex; gap: 12px;
  padding: 14px 16px;
  border-radius: var(--radius-m);
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  border-left: 3px solid var(--accent);
  margin: 0 0 16px;
}
.art-body blockquote p {
  font-size: 13.5px; line-height: 1.55;
  color: var(--text); margin-bottom: 0;
}
.art-body blockquote strong { color: var(--accent); }

/* HR */
.art-body hr { border: none; border-top: 1px solid var(--border); margin: 24px 0; }

/* ── Callout (HTML) ─────────────────────────────────────────────────────────── */
.callout {
  display: flex; gap: 12px; padding: 14px 16px;
  border-radius: var(--radius-m); margin-bottom: 14px;
}
.callout.info {
  background: var(--accent-bg); border: 1px solid var(--accent-border);
}
.callout.warn {
  background: rgba(255,159,10,.08); border: 1px solid rgba(255,159,10,.25);
}
.callout-icon { flex-shrink: 0; margin-top: 1px; }
.callout-icon svg { width: 17px; height: 17px; }
.callout.info .callout-icon svg { color: var(--accent); }
.callout.warn .callout-icon svg { color: #FF9F0A; }
.callout-text { font-size: 13.5px; line-height: 1.55; color: var(--text); }

/* ── TOC sidebar ────────────────────────────────────────────────────────────── */
.toc-label {
  font-size: 11px; font-weight: 600;
  letter-spacing: 0.8px; text-transform: uppercase;
  color: var(--faint); margin-bottom: 8px; padding: 0 4px;
}
.toc-list { list-style: none; }
.toc-item {
  display: flex; align-items: flex-start; gap: 8px;
  padding: 5px 4px; cursor: pointer;
}
.toc-dot {
  width: 5px; height: 5px; flex-shrink: 0;
  border-radius: 50%; background: var(--border);
  margin-top: 7px;
  transition: background .15s;
}
.toc-item.active .toc-dot { background: var(--accent); }
.toc-item a {
  font-size: 13px; color: var(--muted);
  text-decoration: none; line-height: 1.45;
  transition: color .12s;
}
.toc-item.active a { color: var(--accent); font-weight: 500; }
.toc-item a:hover { color: var(--text); }
.toc-back {
  display: flex; align-items: center; gap: 6px;
  font-size: 13px; color: var(--muted);
  text-decoration: none; padding: 7px 4px;
  margin-top: 2px; transition: color .12s;
}
.toc-back svg { width: 14px; height: 14px; flex-shrink: 0; }
.toc-back:hover { color: var(--text); text-decoration: none; }

/* ── Hero ───────────────────────────────────────────────────────────────────── */
.hero {
  background: var(--surface);
  padding: 72px 40px 64px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}
.hero-eyebrow {
  font-size: 11px; font-weight: 700;
  color: var(--accent); letter-spacing: 1.2px;
  text-transform: uppercase; margin-bottom: 16px;
}
.hero-title {
  font-size: 48px; font-weight: 700;
  letter-spacing: -1.5px; line-height: 1.05;
  margin-bottom: 12px;
}
.hero-sub {
  font-size: 17px; color: var(--muted); margin-bottom: 32px;
}
.hero-search {
  display: inline-flex; align-items: center; gap: 10px;
  width: 100%; max-width: 580px; height: 48px;
  padding: 0 6px 0 16px;
  border-radius: var(--radius-m);
  background: var(--bg);
  border: 1px solid var(--border);
  transition: border-color .15s, box-shadow .15s;
}
.hero-search:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-bg);
}
.hero-search svg { width: 17px; height: 17px; color: var(--muted); flex-shrink: 0; }
.hero-search input {
  flex: 1; border: none; background: none; outline: none;
  font-size: 15px; color: var(--text); font-family: var(--font);
}
.hero-search input::placeholder { color: var(--faint); }
.hero-search-btn {
  padding: 8px 16px;
  background: var(--accent); color: #fff;
  border: none; border-radius: var(--radius-s);
  font-size: 13px; font-weight: 600;
  cursor: pointer; font-family: var(--font);
  transition: opacity .15s;
  flex-shrink: 0;
}
.hero-search-btn:hover { opacity: .88; }

/* ── Category grid ──────────────────────────────────────────────────────────── */
.cat-section { padding: 48px 80px; }
.cat-section-title { font-size: 20px; font-weight: 700; margin-bottom: 16px; }
.cat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}
.cat-card {
  display: flex; flex-direction: column; gap: 10px;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-l);
  text-decoration: none; color: inherit;
  transition: box-shadow .15s, border-color .15s, transform .12s;
}
.cat-card:hover {
  box-shadow: 0 4px 20px var(--shadow);
  border-color: var(--accent-border);
  transform: translateY(-1px);
  text-decoration: none; color: inherit;
}
.cat-card-icon svg { width: 26px; height: 26px; color: var(--accent); }
.cat-card-title { font-size: 15px; font-weight: 600; }
.cat-card-desc  { font-size: 13px; color: var(--muted); line-height: 1.5; }

/* ── Responsive ─────────────────────────────────────────────────────────────── */
@media (max-width: 1100px) {
  .cat-grid { grid-template-columns: repeat(2, 1fr); }
  .main { padding: 32px 32px; }
}
@media (max-width: 768px) {
  .nav { padding: 0 20px; }
  .nav-links { display: none; }
  .sidebar { display: none; }
  .cat-section { padding: 32px 20px; }
  .cat-grid { grid-template-columns: 1fr; }
  .hero { padding: 48px 20px 40px; }
  .hero-title { font-size: 36px; letter-spacing: -1px; }
  .main { padding: 24px 20px; }
}

/* ── Scrollbar (WebKit) ─────────────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--faint); }

/* ── Fast Fix widget ────────────────────────────────────────────────────────── */
.ff-btn {
  position: fixed;
  bottom: 28px;
  right: 28px;
  z-index: 900;
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 11px 18px 11px 14px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 50px;
  font: 600 14px/1 var(--font);
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(0,0,0,.22);
  opacity: 0;
  transform: translateY(6px);
  transition: opacity .2s, transform .2s, box-shadow .15s, background .15s;
  pointer-events: none;
}
.ff-btn.ff-visible {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}
.ff-btn:hover { background: var(--accent); box-shadow: 0 6px 28px rgba(0,0,0,.32); filter: brightness(1.08); }
.ff-btn svg { width: 16px; height: 16px; flex-shrink: 0; }

/* Popup */
.ff-popup {
  position: fixed;
  bottom: 80px;
  right: 28px;
  z-index: 901;
  width: 340px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-l);
  box-shadow: 0 12px 48px rgba(0,0,0,.22);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transform: scale(.94) translateY(12px);
  transform-origin: bottom right;
  opacity: 0;
  pointer-events: none;
  transition: transform .22s cubic-bezier(.34,1.56,.64,1), opacity .18s;
}
.ff-popup.ff-open {
  transform: scale(1) translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.ff-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 16px 12px;
  border-bottom: 1px solid var(--border);
}
.ff-header-left { display: flex; align-items: center; gap: 8px; }
.ff-header-icon {
  width: 28px; height: 28px;
  background: var(--accent-bg);
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  color: var(--accent);
}
.ff-header-icon svg { width: 15px; height: 15px; }
.ff-header h3 { font-size: 14px; font-weight: 600; color: var(--text); }
.ff-header p  { font-size: 11px; color: var(--muted); margin-top: 1px; }
.ff-close {
  width: 26px; height: 26px;
  background: var(--border-light);
  border: none; border-radius: 50%;
  cursor: pointer; color: var(--muted);
  display: flex; align-items: center; justify-content: center;
  transition: background .15s;
}
.ff-close:hover { background: var(--border); color: var(--text); }
.ff-close svg { width: 12px; height: 12px; }

.ff-messages {
  flex: 1;
  min-height: 120px;
  max-height: 260px;
  overflow-y: auto;
  padding: 14px 14px 8px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.ff-msg {
  max-width: 88%;
  padding: 9px 12px;
  border-radius: 14px;
  font-size: 13px;
  line-height: 1.5;
  word-break: break-word;
}
.ff-msg-user {
  align-self: flex-end;
  background: var(--accent);
  color: #fff;
  border-bottom-right-radius: 4px;
}
.ff-msg-ai {
  align-self: flex-start;
  background: var(--border-light);
  color: var(--text);
  border-bottom-left-radius: 4px;
}
.ff-msg-hint {
  align-self: center;
  background: none;
  color: var(--muted);
  font-size: 12px;
  padding: 4px 0;
  max-width: 100%;
  text-align: center;
}

/* Typing dots */
.ff-typing {
  align-self: flex-start;
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 10px 14px;
  background: var(--border-light);
  border-radius: 14px;
  border-bottom-left-radius: 4px;
}
.ff-typing span {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--muted);
  animation: ff-bounce .9s infinite ease-in-out;
}
.ff-typing span:nth-child(2) { animation-delay: .15s; }
.ff-typing span:nth-child(3) { animation-delay: .30s; }
@keyframes ff-bounce {
  0%,80%,100% { transform: translateY(0); opacity: .4; }
  40%          { transform: translateY(-5px); opacity: 1; }
}

.ff-footer {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 12px;
  border-top: 1px solid var(--border);
}
.ff-input {
  flex: 1;
  background: var(--border-light);
  border: 1px solid transparent;
  border-radius: 20px;
  padding: 8px 14px;
  font: 13px/1.4 var(--font);
  color: var(--text);
  outline: none;
  resize: none;
  height: 36px;
  transition: border-color .15s, background .15s;
}
.ff-input:focus { border-color: var(--accent-border); background: var(--surface); }
.ff-input::placeholder { color: var(--faint); }
.ff-send {
  width: 34px; height: 34px;
  flex-shrink: 0;
  background: var(--accent);
  border: none; border-radius: 50%;
  cursor: pointer; color: #fff;
  display: flex; align-items: center; justify-content: center;
  transition: opacity .15s, transform .12s;
}
.ff-send:hover { opacity: .88; }
.ff-send:active { transform: scale(.92); }
.ff-send:disabled { opacity: .35; cursor: default; }
.ff-send svg { width: 15px; height: 15px; }

@media (max-width: 480px) {
  .ff-popup { width: calc(100vw - 24px); right: 12px; bottom: 72px; }
  .ff-btn   { right: 12px; bottom: 16px; }
}