:root {
  color-scheme: light;
  --bg: #f6f6f2;
  --surface: #ffffff;
  --surface-soft: #efefe9;
  --surface-strong: #e7e7df;
  --text: #191a17;
  --muted: #676961;
  --border: #dddd d4;
  --accent: #126b50;
  --accent-dark: #0d533e;
  --accent-soft: #dff2e9;
  --danger: #b23b31;
  --code: #171b19;
  --code-text: #eff7f2;
  --shadow: 0 10px 30px rgba(20, 25, 21, .07);
  --radius: 18px;
  --radius-sm: 11px;
  --max: 1180px;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #151714;
  --surface: #1d201c;
  --surface-soft: #252922;
  --surface-strong: #2b3028;
  --text: #f1f3ed;
  --muted: #a7aca2;
  --border: #353b33;
  --accent: #71d3ac;
  --accent-dark: #9ae5c7;
  --accent-soft: #1d3b30;
  --code: #0d100e;
  --code-text: #e9f5ef;
  --shadow: 0 14px 36px rgba(0, 0, 0, .25);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
button, input, select, textarea { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
.skip-link { position: fixed; left: 16px; top: -60px; z-index: 100; padding: 10px 14px; background: var(--text); color: var(--surface); border-radius: 8px; }
.skip-link:focus { top: 12px; }

.topbar { position: sticky; top: 0; z-index: 40; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(16px); border-bottom: 1px solid var(--border); }
.topbar-inner { width: min(var(--max), calc(100% - 32px)); min-height: 72px; margin: 0 auto; display: flex; align-items: center; gap: 28px; }
.brand { display: flex; align-items: center; gap: 11px; text-decoration: none; margin-right: auto; }
.brand-mark { width: 40px; height: 40px; display: grid; place-items: center; border-radius: 12px; background: var(--text); color: var(--surface); font-weight: 800; letter-spacing: -.04em; }
.brand strong, .brand small { display: block; line-height: 1.2; }
.brand strong { font-size: 15px; }
.brand small { margin-top: 3px; color: var(--muted); font-size: 12px; }
.nav-links { display: flex; align-items: center; gap: 4px; }
.nav-links a { text-decoration: none; color: var(--muted); padding: 9px 11px; border-radius: 9px; font-size: 14px; font-weight: 650; }
.nav-links a:hover { color: var(--text); background: var(--surface-soft); }
.icon-button { width: 40px; height: 40px; border: 1px solid var(--border); border-radius: 11px; background: var(--surface); color: var(--text); cursor: pointer; display: grid; place-items: center; }
.icon-button:hover { border-color: var(--muted); }
.icon-button svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.moon-icon { display: none; }
html[data-theme="dark"] .sun-icon { display: none; }
html[data-theme="dark"] .moon-icon { display: block; }

main { width: min(var(--max), calc(100% - 32px)); margin: 0 auto; }
.hero { padding: 84px 0 64px; max-width: 820px; }
.eyebrow { display: inline-flex; align-items: center; gap: 9px; color: var(--accent); font-size: 13px; font-weight: 800; text-transform: uppercase; letter-spacing: .075em; }
.eyebrow span { width: 20px; height: 2px; background: currentColor; }
.eyebrow.plain { display: block; }
.hero h1 { margin: 18px 0 16px; max-width: 760px; font-size: clamp(40px, 7vw, 72px); line-height: .98; letter-spacing: -.065em; font-weight: 780; }
.hero p { max-width: 700px; margin: 0; color: var(--muted); font-size: clamp(17px, 2vw, 20px); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 44px; padding: 0 17px; border-radius: 11px; border: 1px solid transparent; text-decoration: none; cursor: pointer; font-weight: 750; font-size: 14px; transition: transform .15s ease, background .15s ease, border-color .15s ease; }
.button:active { transform: translateY(1px); }
.button.primary { background: var(--accent); color: #fff; }
html[data-theme="dark"] .button.primary { color: #0c231a; }
.button.primary:hover { background: var(--accent-dark); }
.button.secondary { background: var(--surface); color: var(--text); border-color: var(--border); }
.button.secondary:hover, .button.ghost:hover { border-color: var(--muted); }
.button.ghost { background: transparent; color: var(--muted); border-color: var(--border); }
.device-chip { display: inline-flex; margin-top: 24px; padding: 7px 10px; border-radius: 999px; background: var(--accent-soft); color: var(--accent-dark); font-size: 12px; font-weight: 750; }

.tool-layout { display: grid; grid-template-columns: 285px minmax(0, 1fr); gap: 22px; align-items: start; padding-bottom: 84px; }
.tool-menu { position: sticky; top: 94px; background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 10px; box-shadow: var(--shadow); }
.menu-head { padding: 12px 12px 10px; display: flex; justify-content: space-between; color: var(--muted); font-size: 12px; text-transform: uppercase; letter-spacing: .05em; }
.menu-head strong { color: var(--text); }
.tool-tab { width: 100%; border: 0; background: transparent; color: var(--text); display: flex; align-items: center; gap: 11px; padding: 11px; border-radius: 12px; text-align: left; cursor: pointer; }
.tool-tab:hover { background: var(--surface-soft); }
.tool-tab.active { background: var(--accent-soft); }
.tool-icon { flex: 0 0 34px; height: 34px; display: grid; place-items: center; border: 1px solid var(--border); border-radius: 9px; color: var(--muted); font-size: 11px; font-weight: 800; }
.tool-tab.active .tool-icon { background: var(--accent); color: white; border-color: var(--accent); }
html[data-theme="dark"] .tool-tab.active .tool-icon { color: #0c231a; }
.tool-tab strong, .tool-tab small { display: block; }
.tool-tab strong { font-size: 14px; }
.tool-tab small { margin-top: 2px; color: var(--muted); font-size: 12px; }
.tool-panels { min-width: 0; }
.tool-panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: clamp(22px, 4vw, 42px); box-shadow: var(--shadow); min-height: 620px; animation: panelIn .2s ease; }
@keyframes panelIn { from { opacity: .4; transform: translateY(4px); } to { opacity: 1; transform: none; } }
.panel-heading { padding-bottom: 26px; border-bottom: 1px solid var(--border); margin-bottom: 26px; }
.panel-heading > div { display: flex; gap: 12px; align-items: center; }
.panel-number { display: grid; place-items: center; width: 36px; height: 36px; border-radius: 10px; background: var(--text); color: var(--surface); font-size: 12px; font-weight: 800; }
.panel-heading h2 { margin: 0; font-size: clamp(25px, 4vw, 35px); letter-spacing: -.04em; }
.panel-heading p { max-width: 680px; margin: 12px 0 0 48px; color: var(--muted); }
.field { display: grid; gap: 8px; min-width: 0; }
.field > span { color: var(--text); font-size: 13px; font-weight: 750; }
input, select, textarea { width: 100%; border: 1px solid var(--border); border-radius: 11px; background: var(--bg); color: var(--text); padding: 12px 13px; outline: none; }
input, select { min-height: 46px; }
textarea { resize: vertical; min-height: 108px; }
input:focus, select:focus, textarea:focus { border-color: var(--accent); box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 16%, transparent); }
input::placeholder, textarea::placeholder { color: color-mix(in srgb, var(--muted) 75%, transparent); }
.check-row { display: flex; align-items: flex-start; gap: 9px; color: var(--muted); font-size: 14px; cursor: pointer; }
.check-row input { width: 17px; height: 17px; min-height: 0; flex: 0 0 auto; margin-top: 2px; accent-color: var(--accent); }
.check-row code { font-size: 12px; }
.action-row { display: flex; flex-wrap: wrap; gap: 10px; margin: 18px 0; }
.result-box { margin-top: 22px; border: 1px solid var(--border); border-radius: 13px; overflow: hidden; background: var(--bg); }
.result-head { min-height: 44px; display: flex; justify-content: space-between; align-items: center; padding: 8px 12px; border-bottom: 1px solid var(--border); color: var(--muted); font-size: 12px; font-weight: 750; text-transform: uppercase; letter-spacing: .04em; }
.result-box output { display: block; padding: 17px; overflow-wrap: anywhere; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 14px; }
.copy-button { border: 1px solid var(--border); border-radius: 8px; background: var(--surface); color: var(--text); padding: 6px 9px; cursor: pointer; font-size: 12px; font-weight: 750; text-transform: none; letter-spacing: normal; }
.copy-button:hover { border-color: var(--muted); }
.copy-button.light { color: var(--code-text); border-color: #3a433e; background: #272d2a; }
.hidden { display: none !important; }
.form-grid { display: grid; gap: 17px; }
.form-grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.form-grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.form-grid .full { grid-column: 1 / -1; }
.form-grid.compact { margin-top: 16px; }
.option-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px 18px; margin-top: 20px; }
.command-box { margin-top: 24px; background: var(--code); color: var(--code-text); border-radius: 14px; overflow: hidden; box-shadow: inset 0 0 0 1px rgba(255,255,255,.08); }
.command-head { min-height: 48px; display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 8px 13px; border-bottom: 1px solid rgba(255,255,255,.1); font-size: 12px; color: #bdc9c1; font-weight: 750; }
.command-box pre { margin: 0; padding: 18px; overflow-x: auto; white-space: pre-wrap; overflow-wrap: anywhere; }
.command-box code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; line-height: 1.7; }
.small-note { margin: 12px 2px 0; color: var(--muted); font-size: 13px; }
.info-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-top: 22px; }
.info-item { padding: 16px; border: 1px solid var(--border); border-radius: 12px; background: var(--bg); }
.info-item span, .info-item strong { display: block; }
.info-item span { color: var(--muted); font-size: 12px; }
.info-item strong { margin-top: 5px; overflow-wrap: anywhere; }
.thumbnail-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; margin-top: 24px; }
.thumb-card { border: 1px solid var(--border); border-radius: 13px; overflow: hidden; background: var(--bg); }
.thumb-frame { aspect-ratio: 16/9; background: var(--surface-soft); overflow: hidden; }
.thumb-frame img { width: 100%; height: 100%; object-fit: cover; display: block; }
.thumb-card > div:last-child { padding: 12px; }
.thumb-card strong, .thumb-card a { display: block; }
.thumb-card a { color: var(--accent); font-size: 13px; margin-top: 3px; }
.size-result { margin-top: 24px; padding: 24px; border-radius: 15px; background: var(--accent-soft); color: var(--accent-dark); }
.size-result span, .size-result strong, .size-result small { display: block; }
.size-result strong { margin: 3px 0; font-size: clamp(32px, 5vw, 48px); letter-spacing: -.04em; }
.preset-row { display: flex; flex-wrap: wrap; align-items: center; gap: 7px; margin-top: 16px; color: var(--muted); font-size: 12px; }
.preset-row button { border: 1px solid var(--border); border-radius: 999px; background: var(--surface); color: var(--text); padding: 6px 10px; cursor: pointer; }
.mini-result { position: relative; min-height: 86px; padding: 13px; border-radius: 11px; background: var(--accent-soft); }
.mini-result span, .mini-result strong { display: block; }
.mini-result span { color: var(--muted); font-size: 12px; }
.mini-result strong { margin-top: 3px; font-size: 22px; }
.mini-result .copy-button { position: absolute; right: 9px; top: 9px; }
.quick-grid { display: grid; gap: 12px; }
.quick-card { border: 1px solid var(--border); border-radius: 13px; padding: 16px; }
.quick-card > div:first-child span, .quick-card > div:first-child strong { display: block; }
.quick-card > div:first-child span { color: var(--accent); font-size: 12px; font-weight: 800; text-transform: uppercase; letter-spacing: .04em; }
.quick-card > div:first-child strong { margin-top: 2px; }
.inline-code { display: flex; align-items: center; gap: 10px; margin-top: 12px; background: var(--code); color: var(--code-text); padding: 10px; border-radius: 9px; }
.inline-code code { flex: 1; min-width: 0; overflow-wrap: anywhere; font-size: 13px; }
.notice { margin-top: 18px; border-left: 3px solid var(--accent); padding: 13px 15px; background: var(--accent-soft); color: var(--muted); border-radius: 0 10px 10px 0; font-size: 13px; }

.ecosystem { padding: 76px 0 96px; border-top: 1px solid var(--border); }
.ecosystem > div:first-child { display: flex; justify-content: space-between; align-items: end; gap: 20px; }
.ecosystem h2 { margin: 8px 0 0; font-size: clamp(30px, 5vw, 48px); letter-spacing: -.05em; }
.ecosystem-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 12px; margin-top: 28px; }
.ecosystem-grid a { min-height: 180px; padding: 20px; border: 1px solid var(--border); border-radius: 15px; background: var(--surface); text-decoration: none; display: flex; flex-direction: column; transition: transform .15s ease, border-color .15s ease; }
.ecosystem-grid a:hover { transform: translateY(-2px); border-color: var(--muted); }
.ecosystem-grid span { color: var(--accent); font-size: 12px; font-weight: 800; text-transform: uppercase; letter-spacing: .05em; }
.ecosystem-grid strong { margin-top: 9px; line-height: 1.3; }
.ecosystem-grid small { margin-top: auto; color: var(--muted); }
footer { width: min(var(--max), calc(100% - 32px)); margin: 0 auto; padding: 28px 0 40px; border-top: 1px solid var(--border); display: flex; justify-content: space-between; gap: 20px; color: var(--muted); font-size: 13px; }
footer strong, footer span { display: block; }
footer strong { color: var(--text); }
footer button { align-self: start; border: 0; background: none; color: var(--text); cursor: pointer; font-weight: 700; }
.toast { position: fixed; left: 50%; bottom: 24px; z-index: 100; transform: translate(-50%, 30px); opacity: 0; pointer-events: none; padding: 10px 14px; border-radius: 10px; background: var(--text); color: var(--surface); box-shadow: var(--shadow); font-size: 13px; font-weight: 750; transition: .2s ease; }
.toast.show { transform: translate(-50%, 0); opacity: 1; }

@media (max-width: 900px) {
  .nav-links { display: none; }
  .hero { padding-top: 64px; }
  .tool-layout { grid-template-columns: 1fr; }
  .tool-menu { position: static; display: flex; overflow-x: auto; gap: 7px; padding: 8px; scrollbar-width: thin; }
  .menu-head { display: none; }
  .tool-tab { flex: 0 0 auto; width: auto; min-width: 154px; }
  .tool-tab small { display: none; }
  .tool-icon { flex-basis: 30px; height: 30px; }
  .ecosystem-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 640px) {
  body { font-size: 15px; }
  .topbar-inner, main, footer { width: min(100% - 22px, var(--max)); }
  .topbar-inner { min-height: 64px; }
  .brand small { display: none; }
  .hero { padding: 48px 2px 46px; }
  .hero h1 { font-size: clamp(38px, 13vw, 55px); }
  .hero p { font-size: 16px; }
  .hero-actions .button { flex: 1; }
  .tool-layout { gap: 12px; padding-bottom: 60px; }
  .tool-menu { margin-inline: -1px; }
  .tool-tab { min-width: 140px; padding: 9px; }
  .tool-panel { padding: 20px 16px; min-height: 560px; border-radius: 15px; }
  .panel-heading { padding-bottom: 20px; margin-bottom: 20px; }
  .panel-heading > div { align-items: flex-start; }
  .panel-number { width: 32px; height: 32px; flex: 0 0 32px; }
  .panel-heading p { margin-left: 0; }
  .form-grid.two, .form-grid.three, .option-grid, .info-grid, .thumbnail-grid { grid-template-columns: 1fr; }
  .form-grid .full { grid-column: auto; }
  .command-head { align-items: flex-start; }
  .ecosystem { padding: 56px 0 70px; }
  .ecosystem-grid { grid-template-columns: 1fr; }
  .ecosystem-grid a { min-height: 135px; }
  footer { flex-direction: column; }
  .inline-code { align-items: flex-start; flex-direction: column; }
  .inline-code .copy-button { align-self: flex-end; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; transition-duration: .01ms !important; }
}

/* YT Conv ecosystem navigation */
.nav-links a.current{background:var(--text);color:var(--bg);pointer-events:none}
.ecosystem-grid a.current{border-color:var(--text);box-shadow:inset 0 0 0 1px var(--text)}
.ecosystem-grid a.current small{color:var(--text)}