[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"verticals":3,"playground-css-starting-style-entry-animations":32},[4,20],{"id":5,"slug":6,"name":7,"tagline":8,"description":9,"accentFrom":10,"accentTo":11,"icon":12,"defaultLocale":13,"locales":14,"features":16,"position":19},"019fe637-3d33-714b-b57f-23e163ffca0c","dev","Web Development","Build. Learn. Ship.","Practical courses, engineering-grade articles and open-source tools for people who ship.","violet-500","cyan-400","◇","en",[13,15],"fa",{"courses":17,"paths":17,"articles":17,"exams":18,"flashcards":18,"packages":17,"community":17,"certificates":17,"teams":17,"commerce":17},true,false,0,{"id":21,"slug":22,"name":23,"tagline":24,"description":25,"accentFrom":26,"accentTo":10,"icon":27,"defaultLocale":13,"locales":28,"features":30,"position":31},"019fe637-3dc2-754c-8657-0f175bfee7c6","lang","Languages","Learn a language the way you learn a codebase.","Structured paths, listening drills and spaced repetition that actually sticks.","amber-400","⌘",[13,15,29],"es",{"courses":17,"paths":17,"articles":18,"exams":18,"flashcards":18,"packages":18,"community":17,"certificates":18,"teams":18,"commerce":17},2,{"slug":33,"title":34,"summary":35,"html":36,"css":37,"js":38,"config":39,"doc":41},"css-starting-style-entry-animations","@starting-style — interactive playground",null,", this selector no longer matches, so newly\n   * inserted cards get NO \"before\" state and just pop in at their final\n   * opacity\u002Ftransform — the exact problem the at-rule fixes.\n   *\u002F\n  @starting-style {\n    body[data-starting=\"on\"] .toast.preset-fade { opacity: 0; transform: translateY(16px); }\n    body[data-starting=\"on\"] .toast.preset-scale { opacity: 0; transform: translateY(0) scale(0.82); }\n    body[data-starting=\"on\"] .toast.preset-slideleft { opacity: 0; transform: translateX(-28px); }\n  }\n\n  \u002F* ---- bonus demo: display:none -> block via transition-behavior ---- *\u002F\n  .drawer {\n    display: none;\n    opacity: 0;\n    transform: translateY(-10px);\n    background: var(--panel-2);\n    border: 1px solid var(--line);\n    border-radius: var(--radius-sm);\n    padding: 14px 16px;\n    margin-top: 12px;\n    \u002F* `display` needs its own allow-discrete entry in the transition list so\n       the browser knows to keep the element painted for the animation's\n       duration instead of flipping display instantly. *\u002F\n    transition: opacity 0.3s ease, transform 0.3s ease, display 0.3s allow-discrete;\n  }\n  .drawer.open { display: block; opacity: 1; transform: translateY(0); }\n\n  @starting-style {\n    body[data-starting=\"on\"] .drawer.open { opacity: 0; transform: translateY(-10px); }\n  }\n\n  .drawer h3 { margin: 0 0 6px; font-size: 0.92rem; }\n  .drawer p { margin: 0; color: var(--muted); font-size: 0.84rem; }\n\u003C\u002Fstyle>\n\u003C\u002Fhead>\n\u003Cbody>\n  \u003Cdiv class=\"pg\">\n    \u003Ch1 class=\"pg-title\">🎮 \u003Ccode>@starting-style\u003C\u002Fcode> — entry animations without JS\u003C\u002Fh1>\n    \u003Cp class=\"pg-sub\">\n      Click \u003Cb>Add card\u003C\u002Fb>, then flip the toggle off and add another. Same \u003Ccode>transition\u003C\u002Fcode>,\n      same markup — the only difference is whether \u003Ccode>@starting-style\u003C\u002Fcode> gives the browser\n      a \"before\" state to animate from.\n    \u003C\u002Fp>\n\n    \u003Cdiv class=\"banner\" id=\"supportBanner\">\u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">1\u003C\u002Fspan> Controls\u003C\u002Fdiv>\n\n      \u003Cdiv class=\"btn-row\">\n        \u003Cbutton class=\"btn primary\" id=\"addCard\">+ Add card\u003C\u002Fbutton>\n        \u003Cbutton class=\"btn ghost\" id=\"reset\">Reset\u003C\u002Fbutton>\n        \u003Clabel class=\"toggle\" style=\"margin-left: 6px\">\n          \u003Cinput type=\"checkbox\" id=\"startingToggle\" checked \u002F>\n          \u003Cspan class=\"switch\">\u003C\u002Fspan>\n          \u003Cspan>\u003Ccode>@starting-style\u003C\u002Fcode> entry animation\u003C\u002Fspan>\n        \u003C\u002Flabel>\n      \u003C\u002Fdiv>\n\n      \u003Cp class=\"hint\" style=\"margin-top: 10px\">\n        Turn the toggle \u003Cb>off\u003C\u002Fb> to see the old problem: without a \"before\" state, a new card\n        can only jump straight to its final look — there is nothing for \u003Ccode>transition\u003C\u002Fcode>\n        to animate from.\n      \u003C\u002Fp>\n\n      \u003Cdiv class=\"presets\" style=\"margin-top: 14px\" id=\"presetSeg\" role=\"group\" aria-label=\"Entry animation preset\">\n        \u003Cdiv class=\"seg\">\n          \u003Cbutton type=\"button\" data-preset=\"fade\" aria-pressed=\"true\">Fade + slide up\u003C\u002Fbutton>\n          \u003Cbutton type=\"button\" data-preset=\"scale\" aria-pressed=\"false\">Scale pop\u003C\u002Fbutton>\n          \u003Cbutton type=\"button\" data-preset=\"slideleft\" aria-pressed=\"false\">Slide from left\u003C\u002Fbutton>\n        \u003C\u002Fdiv>\n      \u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">2\u003C\u002Fspan> Result — cards entering the DOM\u003C\u002Fdiv>\n      \u003Cdiv class=\"stage-toast\" id=\"stage\">\u003C\u002Fdiv>\n      \u003Cdiv class=\"status\" id=\"status\" style=\"margin-top: 12px\" aria-live=\"polite\">\n        \u003Cspan class=\"dot info\" id=\"dot\">\u003C\u002Fspan>\n        \u003Cspan id=\"statusText\">Ready — add a card to see it enter.\u003C\u002Fspan>\n      \u003C\u002Fdiv>\n      \u003Cp class=\"hint\">Each card is a genuinely new DOM element — no fade class added a tick after mount.\n        Click the ✕ on a card to dismiss it (a normal transition; \u003Ccode>@starting-style\u003C\u002Fcode> only\n        ever applies to how something first appears, never to how it leaves).\u003C\u002Fp>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">3\u003C\u002Fspan> Bonus — revealing a hidden panel\u003C\u002Fdiv>\n      \u003Cdiv class=\"btn-row\">\n        \u003Cbutton class=\"btn\" id=\"drawerBtn\" aria-expanded=\"false\" aria-controls=\"drawer\">Open panel\u003C\u002Fbutton>\n      \u003C\u002Fdiv>\n      \u003Cdiv class=\"drawer\" id=\"drawer\">\n        \u003Ch3>Hidden panel\u003C\u002Fh3>\n        \u003Cp>This element is \u003Ccode>display: none\u003C\u002Fcode> until opened. \u003Ccode>transition-behavior: allow-discrete\u003C\u002Fcode>\n          lets \u003Ccode>display\u003C\u002Fcode> itself join the transition, so the fade-in isn't instant.\u003C\u002Fp>\n      \u003C\u002Fdiv>\n      \u003Cp class=\"hint\" id=\"drawerNote\">\u003C\u002Fp>\n    \u003C\u002Fdiv>\n\n    \u003Cdiv class=\"panel\">\n      \u003Cdiv class=\"panel-label\">\u003Cspan class=\"n\">4\u003C\u002Fspan> The CSS behind card entry (updates live)\u003C\u002Fdiv>\n      \u003Cdiv class=\"code\" id=\"code\">\u003C\u002Fdiv>\n    \u003C\u002Fdiv>\n  \u003C\u002Fdiv>","\u002F*\n * Shared playground design system — daily-post\n * ============================================\n * Link it from any post's playground\u002Findex.html (no per-post boilerplate):\n *\n *   \u003Clink rel=\"stylesheet\" href=\"..\u002F..\u002F..\u002Fplayground\u002Fassets\u002Fbase.css\" \u002F>\n *\n * The relative path resolves the same locally (posts\u002F\u003Cbase>\u002Fplayground\u002F) and on\n * the deployed host (public\u002Fposts\u002F\u003Cbase>\u002Fplayground\u002F), because build-site.js\n * mirrors this file to public\u002Fplayground\u002Fassets\u002Fbase.css. For a CodeSandbox\n * --embed, playground.js inlines this file so the single-file sandbox still styles.\n *\n * Then write ONLY the demo-specific CSS in your inline \u003Cstyle>. Everything below\n * — tokens, layout, panels, buttons, toggles, sliders, code blocks, status\u002Flog,\n * banners, presets — comes for free and looks consistent across every post.\n *\n * Theme-aware: dark by default, light via prefers-color-scheme AND a\n * [data-theme] override on \u003Chtml> (so a toggle can force either). Accessible:\n * real focus rings, adequate contrast, reduced-motion honored.\n *\u002F\n\n\u002F* ---------- design tokens ---------- *\u002F\n:root {\n  --bg: #0d1117;\n  --bg-grid: #ffffff0a;\n  --panel: #161b22;\n  --panel-2: #0b0e14;\n  --card: #0b0e14;\n  --ink: #e8ebf2;\n  --muted: #9aa4b2;\n  --faint: #6b7688;\n  --line: #232a35;\n  --line-soft: #ffffff12;\n  --accent: #7c9cff;\n  --accent-ink: #0b0e14;\n  --good: #3fb950;\n  --warn: #f0883e;\n  --bad: #f85149;\n  --info: #58a6ff;\n  --radius: 14px;\n  --radius-sm: 9px;\n  --shadow: 0 8px 30px #0006;\n  --shadow-sm: 0 4px 14px #0005;\n  --mono: ui-monospace, SFMono-Regular, \"SF Mono\", Menlo, Consolas, \"Liberation Mono\", monospace;\n  --sans: ui-sans-serif, system-ui, -apple-system, \"Segoe UI\", Roboto, \"Helvetica Neue\", sans-serif;\n  color-scheme: dark;\n}\n\n\u002F* Light theme — system preference, overridable by [data-theme] on \u003Chtml>. *\u002F\n@media (prefers-color-scheme: light) {\n  :root:not([data-theme=\"dark\"]) {\n    --bg: #f4f6fb;\n    --bg-grid: #00000008;\n    --panel: #ffffff;\n    --panel-2: #f0f3f9;\n    --card: #f7f9fc;\n    --ink: #131722;\n    --muted: #5b6472;\n    --faint: #8a93a3;\n    --line: #e2e7f0;\n    --line-soft: #00000010;\n    --accent: #2f6df0;\n    --accent-ink: #ffffff;\n    --good: #1a7f37;\n    --warn: #bc4c00;\n    --bad: #cf222e;\n    --info: #0969da;\n    --shadow: 0 8px 30px #0000001f;\n    --shadow-sm: 0 4px 14px #00000014;\n    color-scheme: light;\n  }\n}\n:root[data-theme=\"light\"] {\n  --bg: #f4f6fb;\n  --bg-grid: #00000008;\n  --panel: #ffffff;\n  --panel-2: #f0f3f9;\n  --card: #f7f9fc;\n  --ink: #131722;\n  --muted: #5b6472;\n  --faint: #8a93a3;\n  --line: #e2e7f0;\n  --line-soft: #00000010;\n  --accent: #2f6df0;\n  --accent-ink: #ffffff;\n  --good: #1a7f37;\n  --warn: #bc4c00;\n  --bad: #cf222e;\n  --info: #0969da;\n  --shadow: 0 8px 30px #0000001f;\n  --shadow-sm: 0 4px 14px #00000014;\n  color-scheme: light;\n}\n\n\u002F* ---------- reset & base ---------- *\u002F\n*, *::before, *::after { box-sizing: border-box; }\n\nbody {\n  margin: 0;\n  min-height: 100vh;\n  font-family: var(--sans);\n  color: var(--ink);\n  background:\n    radial-gradient(circle at 1px 1px, var(--bg-grid) 1px, transparent 0) 0 0 \u002F 24px 24px,\n    var(--bg);\n  display: flex;\n  justify-content: center;\n  align-items: flex-start;\n  padding: clamp(14px, 3vw, 26px);\n  line-height: 1.55;\n  -webkit-font-smoothing: antialiased;\n  text-rendering: optimizeLegibility;\n}\n\n\u002F* The single content column. *\u002F\n.pg {\n  width: 100%;\n  max-width: 860px;\n}\n\n\u002F* ---------- header ---------- *\u002F\n.pg-title {\n  font-size: clamp(1.15rem, 1rem + 1vw, 1.4rem);\n  font-weight: 800;\n  letter-spacing: -0.02em;\n  margin: 0 0 4px;\n  display: flex;\n  align-items: center;\n  gap: 9px;\n}\n.pg-sub {\n  color: var(--muted);\n  font-size: 0.92rem;\n  line-height: 1.5;\n  margin: 0 0 16px;\n  max-width: 66ch;\n}\n.pg-sub strong, .pg-sub b { color: var(--ink); font-weight: 700; }\n.pg-sub code { font-family: var(--mono); background: var(--line-soft); color: var(--accent);\n  padding: 1px 6px; border-radius: 6px; font-size: 0.85em; }\n\n\u002F* ---------- panels ---------- *\u002F\n.panel {\n  background: var(--panel);\n  border: 1px solid var(--line);\n  border-radius: var(--radius);\n  padding: 16px 18px;\n  margin-bottom: 14px;\n  box-shadow: var(--shadow-sm);\n}\n.panel-label {\n  font-size: 0.7rem;\n  text-transform: uppercase;\n  letter-spacing: 0.08em;\n  color: var(--muted);\n  font-weight: 800;\n  margin: 0 0 13px;\n  display: flex;\n  align-items: center;\n  gap: 8px;\n}\n.panel-label .n {\n  display: inline-grid; place-items: center;\n  width: 18px; height: 18px; border-radius: 50%;\n  background: var(--accent); color: var(--accent-ink);\n  font-size: 0.66rem; font-weight: 800;\n}\n\n\u002F* ---------- layout helpers ---------- *\u002F\n.row { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }\n.row.between { justify-content: space-between; }\n.col { display: flex; flex-direction: column; gap: 10px; }\n.grow { flex: 1 1 0; min-width: 0; }\n.wrap-controls { display: flex; flex-wrap: wrap; gap: 16px 24px; align-items: flex-end; }\n.field { display: flex; flex-direction: column; gap: 7px; min-width: 0; }\n.field > .label, .ctl-label {\n  font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.04em;\n  color: var(--muted); font-weight: 800;\n}\n\n\u002F* ---------- buttons ---------- *\u002F\n.btn {\n  font: inherit; font-weight: 650; font-size: 0.88rem;\n  cursor: pointer; user-select: none;\n  border: 1px solid var(--line);\n  background: var(--card); color: var(--ink);\n  padding: 9px 15px; border-radius: var(--radius-sm);\n  display: inline-flex; align-items: center; gap: 8px;\n  transition: background .15s ease, border-color .15s ease, transform .05s ease, color .15s ease;\n}\n.btn:hover { background: var(--line-soft); border-color: var(--muted); }\n.btn:active { transform: translateY(1px); }\n.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }\n.btn[disabled] { opacity: 0.45; cursor: not-allowed; }\n.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }\n.btn.primary:hover { filter: brightness(1.08); background: var(--accent); }\n.btn.good { background: var(--good); border-color: var(--good); color: #04140a; }\n.btn.bad  { background: var(--bad);  border-color: var(--bad);  color: #fff; }\n.btn.ghost { background: transparent; }\n.btn.sm { padding: 6px 11px; font-size: 0.82rem; }\n\n.btn-row { display: flex; flex-wrap: wrap; gap: 9px; }\n\n\u002F* Segmented control — a row of buttons where one is active (aria-pressed). *\u002F\n.seg { display: inline-flex; background: var(--card); border: 1px solid var(--line);\n  border-radius: var(--radius-sm); padding: 3px; gap: 3px; }\n.seg button {\n  font: inherit; font-weight: 650; font-size: 0.84rem; cursor: pointer;\n  border: none; background: transparent; color: var(--muted);\n  padding: 7px 13px; border-radius: 7px;\n  transition: background .15s ease, color .15s ease;\n}\n.seg button:hover { color: var(--ink); }\n.seg button[aria-pressed=\"true\"] { background: var(--accent); color: var(--accent-ink); }\n.seg button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }\n\n\u002F* Preset chips — worked-example shortcuts. *\u002F\n.presets { display: flex; flex-wrap: wrap; gap: 8px; }\n.presets .btn { background: var(--panel-2); }\n\n\u002F* ---------- toggle switch ---------- *\u002F\n.toggle { display: inline-flex; align-items: center; gap: 10px; cursor: pointer;\n  font-size: 0.88rem; font-weight: 600; user-select: none; }\n.toggle input { position: absolute; opacity: 0; width: 0; height: 0; }\n.switch { position: relative; width: 44px; height: 25px; border-radius: 999px; flex: none;\n  background: var(--line); border: 1px solid var(--line); transition: background .18s ease; }\n.switch::after { content: \"\"; position: absolute; top: 2px; left: 2px; width: 19px; height: 19px;\n  border-radius: 50%; background: #cfd6e4; transition: transform .18s ease; box-shadow: 0 1px 3px #0006; }\n.toggle input:checked + .switch { background: var(--good); border-color: var(--good); }\n.toggle input:checked + .switch::after { transform: translateX(19px); background: #fff; }\n.toggle input:focus-visible + .switch { outline: 2px solid var(--accent); outline-offset: 2px; }\n\n\u002F* ---------- range slider ---------- *\u002F\ninput[type=\"range\"] {\n  -webkit-appearance: none; appearance: none; width: 100%; height: 6px;\n  background: var(--line); border-radius: 999px; outline: none; cursor: pointer; margin: 8px 0;\n}\ninput[type=\"range\"]::-webkit-slider-thumb {\n  -webkit-appearance: none; appearance: none; width: 19px; height: 19px; border-radius: 50%;\n  background: var(--accent); border: 2px solid var(--panel); box-shadow: var(--shadow-sm); cursor: pointer;\n}\ninput[type=\"range\"]::-moz-range-thumb {\n  width: 19px; height: 19px; border-radius: 50%; background: var(--accent);\n  border: 2px solid var(--panel); box-shadow: var(--shadow-sm); cursor: pointer;\n}\ninput[type=\"range\"]:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }\n\n\u002F* ---------- text inputs \u002F selects ---------- *\u002F\ninput[type=\"text\"], input[type=\"number\"], input[type=\"search\"], select, textarea {\n  font: inherit; color: var(--ink); background: var(--card);\n  border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 8px 11px; width: 100%;\n}\ntextarea { font-family: var(--mono); font-size: 0.85rem; line-height: 1.6; resize: vertical; }\ninput:focus-visible, select:focus-visible, textarea:focus-visible {\n  outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent);\n}\n\n\u002F* ---------- status \u002F output \u002F log ---------- *\u002F\n.status {\n  display: flex; align-items: center; gap: 9px; flex-wrap: wrap;\n  font-size: 0.9rem; font-weight: 600;\n  padding: 11px 14px; border-radius: var(--radius-sm);\n  background: var(--panel-2); border: 1px solid var(--line); color: var(--ink);\n}\n.status.good { border-color: color-mix(in srgb, var(--good) 55%, var(--line)); }\n.status.warn { border-color: color-mix(in srgb, var(--warn) 55%, var(--line)); }\n.status.bad  { border-color: color-mix(in srgb, var(--bad) 55%, var(--line)); }\n.dot { width: 9px; height: 9px; border-radius: 50%; background: var(--muted); flex: none; }\n.dot.good { background: var(--good); } .dot.warn { background: var(--warn); }\n.dot.bad { background: var(--bad); } .dot.info { background: var(--info); }\n\n.output { background: var(--panel-2); border: 1px solid var(--line); border-radius: var(--radius-sm);\n  padding: 13px 15px; }\n.log { font-family: var(--mono); font-size: 0.8rem; line-height: 1.7; background: var(--card);\n  border: 1px solid var(--line); border-radius: var(--radius-sm); padding: 11px 14px;\n  max-height: 220px; overflow-y: auto; white-space: pre-wrap; }\n\n\u002F* ---------- code block + syntax tokens ---------- *\u002F\n.code {\n  font-family: var(--mono); font-size: 0.82rem; line-height: 1.7;\n  background: var(--panel-2); border: 1px solid var(--line); border-radius: var(--radius-sm);\n  padding: 13px 15px; overflow-x: auto; white-space: pre; tab-size: 2;\n}\n.code .tok-sel  { color: var(--accent); }\n.code .tok-prop { color: #86e29b; }\n.code .tok-kw   { color: #ff9bcb; }\n.code .tok-str  { color: #f0c674; }\n.code .tok-num  { color: #f0883e; }\n.code .tok-cmt  { color: var(--faint); font-style: italic; }\n.code .hl { background: color-mix(in srgb, var(--good) 22%, transparent); border-radius: 4px; padding: 0 3px; }\n\n\u002F* ---------- hint \u002F caption ---------- *\u002F\n.hint { font-size: 0.83rem; color: var(--muted); line-height: 1.55; margin: 10px 0 0; }\n.hint code { font-family: var(--mono); color: var(--ink); background: var(--line-soft);\n  padding: 1px 5px; border-radius: 5px; font-size: 0.86em; }\n.hint strong { color: var(--ink); }\n\n\u002F* ---------- banner (feature-support \u002F notices) ---------- *\u002F\n.banner {\n  display: none; margin-bottom: 14px; padding: 11px 14px; border-radius: 11px;\n  font-size: 0.85rem; line-height: 1.5;\n  color: var(--ink); background: color-mix(in srgb, var(--warn) 12%, var(--panel));\n  border: 1px solid color-mix(in srgb, var(--warn) 45%, var(--line));\n}\n.banner.show { display: block; }\n.banner.info { background: color-mix(in srgb, var(--info) 12%, var(--panel));\n  border-color: color-mix(in srgb, var(--info) 45%, var(--line)); }\n.banner code { font-family: var(--mono); background: var(--line-soft); padding: 1px 5px; border-radius: 5px; }\n\n\u002F* ---------- misc atoms ---------- *\u002F\n.pill { display: inline-flex; align-items: center; gap: 6px; font-size: 0.75rem; font-weight: 700;\n  padding: 3px 9px; border-radius: 999px; background: var(--line-soft); color: var(--muted); }\n.pill.good { color: var(--good); background: color-mix(in srgb, var(--good) 16%, transparent); }\n.pill.bad  { color: var(--bad);  background: color-mix(in srgb, var(--bad) 16%, transparent); }\n.mono { font-family: var(--mono); }\n.muted { color: var(--muted); }\n.big-num { font-family: var(--mono); font-size: 1.6rem; font-weight: 800; letter-spacing: -0.02em; }\n\n\u002F* Optional theme toggle button (top-right). Wire it in JS if you want it. *\u002F\n.theme-btn { position: fixed; top: 12px; right: 12px; z-index: 20; }\n\n\u002F* ---------- responsive ---------- *\u002F\n@media (max-width: 560px) {\n  .panel { padding: 14px; }\n  .wrap-controls { gap: 14px; }\n  .btn { padding: 9px 13px; }\n}\n\n\u002F* ---------- reduced motion ---------- *\u002F\n@media (prefers-reduced-motion: reduce) {\n  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }\n}\n\n\n\u002F* Demo-specific CSS ONLY. base.css already provides tokens, layout, panels,\n     buttons, toggles, sliders, code blocks, status\u002Flog, banners, presets. *\u002F\n\n  .stage-toast {\n    display: flex;\n    flex-direction: column;\n    gap: 10px;\n    min-height: 100px;\n  }\n  .stage-toast:empty::before {\n    content: \"No cards yet — click \\201C Add card\\201D above.\";\n    color: var(--faint);\n    font-size: 0.85rem;\n    align-self: flex-start;\n  }\n\n  .toast {\n    display: flex;\n    align-items: center;\n    justify-content: space-between;\n    gap: 12px;\n    background: var(--card);\n    border: 1px solid var(--line);\n    border-radius: var(--radius-sm);\n    padding: 12px 14px;\n    box-shadow: var(--shadow-sm);\n    opacity: 1;\n    transform: translateY(0) scale(1);\n    \u002F* Only opacity\u002Ftransform transition here — no `display` involved, because\n       these cards are real elements being inserted\u002Fremoved from the DOM, not\n       toggled via display:none. That's the panel demo below. *\u002F\n    transition: opacity 0.35s ease, transform 0.35s ease;\n  }\n  .toast .msg { font-size: 0.86rem; line-height: 1.45; }\n  .toast .msg b { color: var(--ink); }\n  .toast .dismiss {\n    flex: none;\n    background: none;\n    border: 1px solid transparent;\n    color: var(--muted);\n    cursor: pointer;\n    font-size: 1rem;\n    line-height: 1;\n    padding: 3px 9px;\n    border-radius: 7px;\n  }\n  .toast .dismiss:hover { color: var(--ink); background: var(--line-soft); }\n  .toast .dismiss:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }\n\n  \u002F* The exit side is a plain transition between two already-rendered states —\n     @starting-style has nothing to do with removal, only with first render. *\u002F\n  .toast.leaving { opacity: 0; transform: translateY(-8px) scale(0.96); }\n\n  \u002F*\n   * @starting-style is gated behind body[data-starting=\"on\"] purely so the\n   * toggle below can switch it off. When the toggle is off, JS sets\n   * data-starting=\"off\" on \u003Cbody>, this selector no longer matches, so newly\n   * inserted cards get NO \"before\" state and just pop in at their final\n   * opacity\u002Ftransform — the exact problem the at-rule fixes.\n   *\u002F\n  @starting-style {\n    body[data-starting=\"on\"] .toast.preset-fade { opacity: 0; transform: translateY(16px); }\n    body[data-starting=\"on\"] .toast.preset-scale { opacity: 0; transform: translateY(0) scale(0.82); }\n    body[data-starting=\"on\"] .toast.preset-slideleft { opacity: 0; transform: translateX(-28px); }\n  }\n\n  \u002F* ---- bonus demo: display:none -> block via transition-behavior ---- *\u002F\n  .drawer {\n    display: none;\n    opacity: 0;\n    transform: translateY(-10px);\n    background: var(--panel-2);\n    border: 1px solid var(--line);\n    border-radius: var(--radius-sm);\n    padding: 14px 16px;\n    margin-top: 12px;\n    \u002F* `display` needs its own allow-discrete entry in the transition list so\n       the browser knows to keep the element painted for the animation's\n       duration instead of flipping display instantly. *\u002F\n    transition: opacity 0.3s ease, transform 0.3s ease, display 0.3s allow-discrete;\n  }\n  .drawer.open { display: block; opacity: 1; transform: translateY(0); }\n\n  @starting-style {\n    body[data-starting=\"on\"] .drawer.open { opacity: 0; transform: translateY(-10px); }\n  }\n\n  .drawer h3 { margin: 0 0 6px; font-size: 0.92rem; }\n  .drawer p { margin: 0; color: var(--muted); font-size: 0.84rem; }","\"use strict\";\n  const $ = (id) => document.getElementById(id);\n\n  const stage = $(\"stage\");\n  const statusText = $(\"statusText\");\n  const dot = $(\"dot\");\n  const codeEl = $(\"code\");\n  const drawer = $(\"drawer\");\n  const drawerBtn = $(\"drawerBtn\");\n  const drawerNote = $(\"drawerNote\");\n  const startingToggle = $(\"startingToggle\");\n  const presetSeg = $(\"presetSeg\");\n  const supportBanner = $(\"supportBanner\");\n\n  let preset = \"fade\";\n  let count = 0;\n  const MAX_CARDS = 6;\n\n  const PRESET_LABEL = {\n    fade: \"opacity 0 → 1, translateY(16px) → 0\",\n    scale: \"opacity 0 → 1, scale(0.82) → 1\",\n    slideleft: \"opacity 0 → 1, translateX(-28px) → 0\",\n  };\n\n  \u002F\u002F One full code snippet per (preset × toggle state) — written out rather than\n  \u002F\u002F string-built on the fly, so nothing is ambiguous about what CSS is \"real\".\n  const CODE = {\n    fade: {\n      on:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateY(\u003Cspan class=\"tok-num\">0\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-kw\">@starting-style\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n    \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">0\u003C\u002Fspan>;\n    \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateY(\u003Cspan class=\"tok-num\">16px\u003C\u002Fspan>);\n  }\n}`,\n      off:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateY(\u003Cspan class=\"tok-num\">0\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-cmt\">\u002F* toggle is OFF — this selector never\n   matches, so .toast has no \"before\"\n   state. The card just appears at its\n   final opacity\u002Ftransform instantly. *\u002F\u003C\u002Fspan>`,\n    },\n    scale: {\n      on:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: scale(\u003Cspan class=\"tok-num\">1\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-kw\">@starting-style\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n    \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">0\u003C\u002Fspan>;\n    \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: scale(\u003Cspan class=\"tok-num\">.82\u003C\u002Fspan>);\n  }\n}`,\n      off:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: scale(\u003Cspan class=\"tok-num\">1\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-cmt\">\u002F* toggle is OFF — no \"before\" state,\n   so the card pops straight to\n   scale(1) with no visible pop-in. *\u002F\u003C\u002Fspan>`,\n    },\n    slideleft: {\n      on:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateX(\u003Cspan class=\"tok-num\">0\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-kw\">@starting-style\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n    \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">0\u003C\u002Fspan>;\n    \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateX(\u003Cspan class=\"tok-num\">-28px\u003C\u002Fspan>);\n  }\n}`,\n      off:\n`\u003Cspan class=\"tok-sel\">.toast\u003C\u002Fspan> {\n  \u003Cspan class=\"tok-prop\">opacity\u003C\u002Fspan>: \u003Cspan class=\"tok-num\">1\u003C\u002Fspan>;\n  \u003Cspan class=\"tok-prop\">transform\u003C\u002Fspan>: translateX(\u003Cspan class=\"tok-num\">0\u003C\u002Fspan>);\n  \u003Cspan class=\"tok-prop\">transition\u003C\u002Fspan>: opacity \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease, transform \u003Cspan class=\"tok-num\">.35s\u003C\u002Fspan> ease;\n}\n\n\u003Cspan class=\"tok-cmt\">\u002F* toggle is OFF — no \"before\" state,\n   so the card appears already at\n   translateX(0), fully in place. *\u002F\u003C\u002Fspan>`,\n    },\n  };\n\n  function setStatus(text, kind = \"info\") {\n    statusText.textContent = text;\n    dot.className = \"dot \" + kind;\n  }\n\n  function syncBody() {\n    document.body.dataset.starting = startingToggle.checked ? \"on\" : \"off\";\n  }\n\n  function buildCode() {\n    codeEl.innerHTML = CODE[preset][startingToggle.checked ? \"on\" : \"off\"];\n  }\n\n  function syncDrawerNote() {\n    drawerNote.innerHTML = startingToggle.checked\n      ? 'Toggle above is \u003Cb>ON\u003C\u002Fb> — \u003Ccode>@starting-style\u003C\u002Fcode> gives the panel a \"before\" state, so opening it fades and slides down.'\n      : 'Toggle above is \u003Cb>OFF\u003C\u002Fb> — \u003Ccode>@starting-style\u003C\u002Fcode> is unmatched, so opening the panel just snaps into view with no transition.';\n  }\n\n  function dismiss(el) {\n    el.classList.add(\"leaving\");\n    let done = false;\n    const finish = () => {\n      if (done) return;\n      done = true;\n      el.remove();\n    };\n    el.addEventListener(\"transitionend\", finish, { once: true });\n    \u002F\u002F Safety net only — in case transitionend never fires (e.g. an interrupted\n    \u002F\u002F transition). Not used to trigger the entry animation itself.\n    setTimeout(finish, 450);\n  }\n\n  $(\"addCard\").addEventListener(\"click\", () => {\n    if (stage.children.length >= MAX_CARDS) {\n      setStatus(\"Stage is full — dismiss a card or hit Reset first.\", \"warn\");\n      return;\n    }\n    count++;\n    const t = document.createElement(\"div\");\n    t.className = \"toast preset-\" + preset;\n    t.innerHTML =\n      '\u003Cspan class=\"msg\">\u003Cb>Card #' + count + \"\u003C\u002Fb> — \" + PRESET_LABEL[preset] + \"\u003C\u002Fspan>\" +\n      '\u003Cbutton type=\"button\" class=\"dismiss\" aria-label=\"Dismiss card ' + count + '\">✕\u003C\u002Fbutton>';\n    stage.appendChild(t);\n    t.querySelector(\".dismiss\").addEventListener(\"click\", () => dismiss(t));\n\n    setStatus(\n      startingToggle.checked\n        ? \"Card #\" + count + ' added — @starting-style gave it a \"before\" state, so it eased in.'\n        : \"Card #\" + count + \" added — no @starting-style, so it just appeared instantly (the old problem).\",\n      startingToggle.checked ? \"good\" : \"warn\"\n    );\n  });\n\n  presetSeg.addEventListener(\"click\", (e) => {\n    const btn = e.target.closest(\"button[data-preset]\");\n    if (!btn) return;\n    preset = btn.dataset.preset;\n    [...presetSeg.querySelectorAll(\"button\")].forEach((b) =>\n      b.setAttribute(\"aria-pressed\", String(b === btn))\n    );\n    buildCode();\n  });\n\n  startingToggle.addEventListener(\"change\", () => {\n    syncBody();\n    buildCode();\n    syncDrawerNote();\n    setStatus(\n      startingToggle.checked\n        ? \"@starting-style entry animation is ON.\"\n        : \"@starting-style is OFF — new cards will pop in with no animation.\",\n      \"info\"\n    );\n  });\n\n  drawerBtn.addEventListener(\"click\", () => {\n    const willOpen = !drawer.classList.contains(\"open\");\n    drawer.classList.toggle(\"open\", willOpen);\n    drawerBtn.setAttribute(\"aria-expanded\", String(willOpen));\n    drawerBtn.textContent = willOpen ? \"Close panel\" : \"Open panel\";\n  });\n\n  $(\"reset\").addEventListener(\"click\", () => {\n    stage.innerHTML = \"\";\n    count = 0;\n    preset = \"fade\";\n    [...presetSeg.querySelectorAll(\"button\")].forEach((b) =>\n      b.setAttribute(\"aria-pressed\", b.dataset.preset === \"fade\" ? \"true\" : \"false\")\n    );\n    startingToggle.checked = true;\n    syncBody();\n    drawer.classList.remove(\"open\");\n    drawerBtn.setAttribute(\"aria-expanded\", \"false\");\n    drawerBtn.textContent = \"Open panel\";\n    buildCode();\n    syncDrawerNote();\n    setStatus(\"Reset — stage cleared, entry animation back on.\", \"info\");\n  });\n\n  \u002F\u002F Feature check: @starting-style support itself is unreliable to detect via\n  \u002F\u002F CSS.supports (at-rule support isn't consistently queryable), so we check\n  \u002F\u002F the sibling property both features shipped alongside — if a browser lacks\n  \u002F\u002F transition-behavior, it predates this whole feature set. The UI still\n  \u002F\u002F works either way; elements just won't animate in on unsupported browsers.\n  (function checkSupport() {\n    const supported =\n      window.CSS && CSS.supports && CSS.supports(\"transition-behavior\", \"allow-discrete\");\n    if (!supported) {\n      supportBanner.textContent =\n        \"Your browser doesn't support transition-behavior: allow-discrete yet, so the animations \" +\n        \"below won't play — cards and the panel still appear, just without the fade\u002Fslide. Try a \" +\n        \"recent Chrome, Edge, Firefox, or Safari.\";\n      supportBanner.classList.add(\"show\");\n    }\n  })();\n\n  syncBody();\n  buildCode();\n  syncDrawerNote();",{"height":40,"autorun":17},520,{"slug":33,"title":42,"excerpt":43,"coverUrl":44},"You use a setTimeout to trigger CSS entry animations. `@starting-style` makes it unnecessary.","Before `@starting-style`, the moment an element entered the DOM was invisible to CSS — transitions had no 'before' state to interpolate from. The at-rule gives you one, natively, with no JavaScript required.","\u002Fmedia\u002Fcovers\u002Fcss-starting-style-entry-animations.png"]