Claude Haiku 5.5
by AnthropicReasoningClean
Running live in a sandboxed frame. Click inside it before using the keyboard.
How it went
- Total time
- 2 min 6 s
- Cost
- $0.016
- Output tokens
- 32,260
- Spent thinking
- 22,761 tokens
- Speed
- 260.4 tok/s
- Console errors
- 0
- First token after
- 1.7 s
- First visible text after
- 1 min 40 s
- Prompt tokens
- 745
- Code size
- 22.1 KB
- Finish reason
- stop
- Served by
- Claude Platform on AWS
- Model id
anthropic/claude-haiku-5.5- Reasoning sent
{"effort":"high"}- Max output
- 128,000 tokens
- Generated
- Nov 11, 2026
What it was asked
The prompt
Build an interactive Kanban board in vanilla HTML, CSS and JavaScript (no framework, no library). Requirements: - Three columns: "To do", "In progress", "Done", each showing its card count. - Pre-populate the board with 6 realistic cards spread across the columns so the first screenshot looks alive. - Each card has a title and a priority (low / medium / high) shown as a colored badge. - Add a card through a small modal form (title required), and delete a card with a button on it. - Drag and drop cards between columns with the mouse, with a clear visual drop indicator. - A search field that filters cards live by title. - A light / dark theme toggle. - State lives in memory only (no storage APIs).
System prompt, sent with every prompt
You are generating a self-contained web demo. It will be rendered automatically in a sandboxed iframe and compared side by side with the output of other AI models given the exact same task. Output rules: - Reply with exactly ONE fenced code block containing the complete file: ```html (or ```svg when the task asks for an SVG). No text before or after the code block. - Everything must be inline: CSS in <style>, JavaScript in <script>. No external files, images, fonts or network requests, except the CDN URLs explicitly allowed by the task. - Do not use localStorage, sessionStorage, cookies, IndexedDB, alert(), confirm(), prompt() or window.open(): they are blocked in the sandbox and will throw. - The page must look right in a 1280×800 viewport and adapt gracefully down to 375px wide. No horizontal scrollbar. - Something meaningful must be visible on first paint: a screenshot is taken automatically about 3 seconds after load, without any interaction. - Everything that makes the demo interesting must be visible within the first seconds: nothing hidden behind a high score, a later level or a long play session. - Games must start in a self-playing demo mode (a simple AI plays) behind a "Click or press a key to start" message, so the game can be judged in action without playing. - The iframe only receives keyboard events after the user clicks it: if the demo uses the keyboard, display a clear "Click or press a key to start" message. - The code must run with zero errors in the console of the latest Chrome.
Code run-1.html · 644 lines
<!DOCTYPE html>
<html lang="en" data-theme="light">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<title>Kanban Board</title>
<style>
:root {
--bg: #f3f4f8;
--surface: #ffffff;
--col-bg: #e9ebf1;
--text: #1c2231;
--muted: #6a7286;
--border: #dde1ea;
--accent: #4b6bfb;
--accent-soft: rgba(75, 107, 251, .18);
--accent-text: #ffffff;
--shadow: 0 1px 2px rgba(20, 28, 45, .06), 0 2px 6px rgba(20, 28, 45, .06);
--hover: rgba(20, 28, 45, .05);
--low-bg: #dcf6e8; --low-fg: #13703f;
--med-bg: #fff0cc; --med-fg: #8a5300;
--high-bg: #ffe0df; --high-fg: #b3261e;
--danger: #d43d3d;
color-scheme: light;
}
html[data-theme="dark"] {
--bg: #0f1218;
--surface: #181d26;
--col-bg: #131821;
--text: #e7eaf1;
--muted: #8c94a7;
--border: #2a3240;
--accent: #7d93ff;
--accent-soft: rgba(125, 147, 255, .22);
--accent-text: #0d1220;
--shadow: 0 1px 2px rgba(0, 0, 0, .4);
--hover: rgba(255, 255, 255, .06);
--low-bg: rgba(46, 204, 128, .16); --low-fg: #6fe0a6;
--med-bg: rgba(245, 178, 56, .16); --med-fg: #f7c76e;
--high-bg: rgba(240, 80, 80, .18); --high-fg: #ff8e8e;
--danger: #ff7a7a;
color-scheme: dark;
}
*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html, body { margin: 0; min-height: 100%; }
body {
font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
background: var(--bg);
color: var(--text);
font-size: 14px;
overflow-x: hidden;
transition: background .2s, color .2s;
}
button, input, select { font: inherit; color: inherit; }
h1, h2, p { margin: 0; }
.sr-only {
position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
/* ---------- Top bar ---------- */
.topbar {
position: sticky; top: 0; z-index: 10;
display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between;
gap: 12px 20px; padding: 14px 24px;
background: var(--surface); border-bottom: 1px solid var(--border);
}
.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }
.logo {
width: 30px; height: 30px; border-radius: 8px; flex: none;
background: var(--accent); color: var(--accent-text);
display: grid; place-items: center; font-weight: 700;
}
h1 { font-size: 17px; font-weight: 650; }
.project {
color: var(--muted); font-size: 13px; white-space: nowrap;
overflow: hidden; text-overflow: ellipsis;
}
.tools { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.search { position: relative; display: flex; align-items: center; }
.search svg {
position: absolute; left: 10px; width: 16px; height: 16px;
color: var(--muted); pointer-events: none;
}
.search input {
width: 240px; height: 36px; padding: 0 12px 0 34px;
border: 1px solid var(--border); border-radius: 8px;
background: var(--bg); outline: none;
}
.search input::placeholder { color: var(--muted); }
.btn {
height: 36px; padding: 0 14px; border-radius: 8px;
border: 1px solid var(--border); background: var(--surface);
cursor: pointer; display: inline-flex; align-items: center; justify-content: center;
gap: 6px; white-space: nowrap; font-weight: 500;
transition: background .15s, filter .15s;
}
.btn:hover { background: var(--hover); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.btn.primary:hover { filter: brightness(1.08); background: var(--accent); }
.btn.icon { width: 36px; padding: 0; }
.btn.icon svg { width: 17px; height: 17px; }
html[data-theme="light"] .i-sun { display: none; }
html[data-theme="dark"] .i-moon { display: none; }
.search input:focus, .field input:focus, .field select:focus {
border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft);
}
.btn:focus-visible, .icon-btn:focus-visible, .add-btn:focus-visible {
outline: 2px solid var(--accent); outline-offset: 2px;
}
/* ---------- Board ---------- */
.board {
display: grid; grid-template-columns: repeat(3, minmax(0, 1fr));
gap: 16px; padding: 20px 24px 32px; align-items: stretch;
}
.column {
display: flex; flex-direction: column; gap: 10px; min-width: 0;
background: var(--col-bg); border: 1.5px solid transparent;
border-radius: 14px; padding: 12px; min-height: 420px;
transition: border-color .15s, background .15s;
}
.column.over { border-color: var(--accent); border-style: dashed; }
.col-head { display: flex; align-items: center; gap: 8px; padding: 2px 4px 4px; }
.dot { width: 9px; height: 9px; border-radius: 50%; flex: none; }
.col-head h2 { font-size: 14px; font-weight: 650; flex: 1; }
.count {
min-width: 26px; height: 22px; padding: 0 8px; border-radius: 999px;
background: var(--surface); color: var(--muted); border: 1px solid var(--border);
font-size: 12px; font-weight: 600; font-variant-numeric: tabular-nums;
display: inline-grid; place-items: center;
}
.list { display: flex; flex-direction: column; gap: 10px; flex: 1; min-height: 120px; }
.empty {
border: 1.5px dashed var(--border); border-radius: 10px; padding: 18px;
text-align: center; color: var(--muted); font-size: 13px;
}
.list.drop-target .empty { display: none; }
.card {
background: var(--surface); border: 1px solid var(--border);
border-radius: 10px; padding: 12px 12px 10px; box-shadow: var(--shadow);
cursor: grab; user-select: none;
transition: opacity .15s, transform .15s;
}
.card:active { cursor: grabbing; }
.card.dragging { opacity: .4; }
.card.removing { opacity: 0; transform: scale(.96); }
.card.flash { animation: flash 1.2s ease; }
@keyframes flash {
0% { box-shadow: 0 0 0 4px var(--accent-soft), var(--shadow); }
100% { box-shadow: var(--shadow); }
}
.card-title {
margin: 0 0 10px; font-size: 14px; line-height: 1.4; font-weight: 500;
overflow-wrap: anywhere;
}
.card-foot { display: flex; align-items: center; gap: 8px; }
.meta { flex: 1; font-size: 12px; color: var(--muted); font-variant-numeric: tabular-nums; }
.badge {
font-size: 11.5px; font-weight: 600; padding: 3px 9px; border-radius: 999px;
text-transform: capitalize; letter-spacing: .01em;
}
.badge.low { background: var(--low-bg); color: var(--low-fg); }
.badge.medium { background: var(--med-bg); color: var(--med-fg); }
.badge.high { background: var(--high-bg); color: var(--high-fg); }
.icon-btn {
width: 28px; height: 28px; border: 0; border-radius: 7px;
background: transparent; color: var(--muted); cursor: pointer;
font-size: 18px; line-height: 1; display: grid; place-items: center;
}
.icon-btn:hover { background: var(--hover); color: var(--danger); }
.drop-indicator {
height: 4px; flex: none; border-radius: 4px; background: var(--accent);
box-shadow: 0 0 0 3px var(--accent-soft);
}
.add-btn {
height: 36px; border-radius: 10px; border: 1px dashed var(--border);
background: transparent; color: var(--muted); cursor: pointer; font-weight: 500;
transition: background .15s, color .15s, border-color .15s;
}
.add-btn:hover { color: var(--text); border-color: var(--muted); background: var(--surface); }
/* ---------- Modal ---------- */
.backdrop {
position: fixed; inset: 0; z-index: 50;
background: rgba(8, 10, 16, .55); backdrop-filter: blur(2px);
display: grid; place-items: center; padding: 16px;
}
.modal {
width: min(420px, 100%); background: var(--surface);
border: 1px solid var(--border); border-radius: 14px; padding: 22px;
box-shadow: 0 20px 50px rgba(0, 0, 0, .3);
display: flex; flex-direction: column; gap: 14px;
}
.modal h2 { font-size: 17px; font-weight: 650; }
.field { display: flex; flex-direction: column; gap: 6px; font-size: 13px; color: var(--muted); font-weight: 500; }
.field input, .field select {
height: 38px; padding: 0 10px; border: 1px solid var(--border); border-radius: 8px;
background: var(--bg); color: var(--text); outline: none; width: 100%;
}
.field input[aria-invalid="true"] { border-color: var(--danger); }
.row2 { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.error { margin: -6px 0 0; color: var(--danger); font-size: 12.5px; }
.actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 4px; }
/* ---------- Responsive ---------- */
@media (max-width: 900px) {
.search input { width: 200px; }
}
@media (max-width: 760px) {
.board { grid-template-columns: 1fr; padding: 14px; gap: 14px; }
.topbar { padding: 12px 14px; }
.project { display: none; }
.search { flex: 1 1 100%; }
.search input { width: 100%; }
.column { min-height: 0; }
.list { min-height: 80px; }
}
</style>
</head>
<body>
<header class="topbar">
<div class="brand">
<div class="logo" aria-hidden="true">K</div>
<h1>Kanban</h1>
<span class="project">Website relaunch · Sprint 14</span>
</div>
<div class="tools">
<label class="search">
<span class="sr-only">Search cards by title</span>
<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" aria-hidden="true">
<circle cx="11" cy="11" r="7"/><path d="M20 20l-3.5-3.5"/>
</svg>
<input id="search" type="search" placeholder="Search cards… (press /)" autocomplete="off" />
</label>
<button id="newBtn" class="btn primary" type="button">+ New card</button>
<button id="themeBtn" class="btn icon" type="button" aria-label="Switch to dark theme" title="Toggle theme">
<svg class="i-moon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
<path d="M21 12.8A9 9 0 1 1 11.2 3a7 7 0 0 0 9.8 9.8z"/>
</svg>
<svg class="i-sun" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" aria-hidden="true">
<circle cx="12" cy="12" r="4"/>
<path d="M12 2v2M12 20v2M4.9 4.9l1.4 1.4M17.7 17.7l1.4 1.4M2 12h2M20 12h2M4.9 19.1l1.4-1.4M17.7 6.3l1.4-1.4"/>
</svg>
</button>
</div>
</header>
<main class="board" id="board"></main>
<div class="backdrop" id="backdrop" hidden>
<form class="modal" id="cardForm" novalidate role="dialog" aria-modal="true" aria-labelledby="modalTitle">
<h2 id="modalTitle">New card</h2>
<label class="field">Title
<input id="cardTitle" name="title" maxlength="120" autocomplete="off" placeholder="e.g. Write onboarding checklist" />
</label>
<p class="error" id="titleError" hidden>A title is required.</p>
<div class="row2">
<label class="field">Priority
<select name="priority">
<option value="low">Low</option>
<option value="medium" selected>Medium</option>
<option value="high">High</option>
</select>
</label>
<label class="field">Column
<select name="status">
<option value="todo">To do</option>
<option value="doing">In progress</option>
<option value="done">Done</option>
</select>
</label>
</div>
<div class="actions">
<button class="btn" type="button" id="cancelBtn">Cancel</button>
<button class="btn primary" type="submit">Add card</button>
</div>
</form>
</div>
<script>
(() => {
'use strict';
// ---------- State (memory only) ----------
const COLUMNS = [
{ id: 'todo', name: 'To do', color: '#8c94a7' },
{ id: 'doing', name: 'In progress', color: '#4b6bfb' },
{ id: 'done', name: 'Done', color: '#22a06b' },
];
let cards = [
{ id: 1, title: 'Draft onboarding email sequence', priority: 'medium', status: 'todo' },
{ id: 2, title: 'Audit third-party dependency licenses', priority: 'low', status: 'todo' },
{ id: 3, title: 'Fix checkout tax rounding for EU orders', priority: 'high', status: 'doing' },
{ id: 4, title: 'Redesign settings page navigation', priority: 'medium', status: 'doing' },
{ id: 5, title: 'Set up CI dependency caching', priority: 'low', status: 'done' },
{ id: 6, title: 'Migrate user avatars to the CDN', priority: 'medium', status: 'done' },
];
let nextId = 7;
let query = '';
let dragId = null;
let justAddedId = null;
let lastFocus = null;
// ---------- Elements ----------
const board = document.getElementById('board');
const search = document.getElementById('search');
const newBtn = document.getElementById('newBtn');
const themeBtn = document.getElementById('themeBtn');
const backdrop = document.getElementById('backdrop');
const form = document.getElementById('cardForm');
const titleInput = document.getElementById('cardTitle');
const titleError = document.getElementById('titleError');
const cancelBtn = document.getElementById('cancelBtn');
// One shared drop indicator, moved around while dragging.
const indicator = document.createElement('div');
indicator.className = 'drop-indicator';
indicator.setAttribute('aria-hidden', 'true');
// ---------- Build columns once ----------
const cols = {};
for (const col of COLUMNS) {
const section = document.createElement('section');
section.className = 'column';
section.dataset.status = col.id;
section.setAttribute('aria-label', col.name);
const head = document.createElement('header');
head.className = 'col-head';
const dot = document.createElement('span');
dot.className = 'dot';
dot.style.background = col.color;
const title = document.createElement('h2');
title.textContent = col.name;
const count = document.createElement('span');
count.className = 'count';
head.append(dot, title, count);
const list = document.createElement('div');
list.className = 'list';
const add = document.createElement('button');
add.type = 'button';
add.className = 'add-btn';
add.textContent = '+ Add card';
add.addEventListener('click', () => openModal(col.id, add));
section.append(head, list, add);
board.append(section);
cols[col.id] = { section, list, count };
wireColumn(section, list);
}
// ---------- Rendering ----------
function matches(card) {
return !query || card.title.toLowerCase().includes(query);
}
function buildCard(card) {
const el = document.createElement('article');
el.className = 'card';
el.draggable = true;
el.dataset.id = String(card.id);
if (card.id === justAddedId) el.classList.add('flash');
const title = document.createElement('p');
title.className = 'card-title';
title.textContent = card.title;
const foot = document.createElement('div');
foot.className = 'card-foot';
const badge = document.createElement('span');
badge.className = `badge ${card.priority}`;
badge.textContent = card.priority;
const meta = document.createElement('span');
meta.className = 'meta';
meta.textContent = `KAN-${card.id}`;
const del = document.createElement('button');
del.type = 'button';
del.className = 'icon-btn';
del.title = 'Delete card';
del.setAttribute('aria-label', `Delete card: ${card.title}`);
del.innerHTML = '×';
del.addEventListener('click', (e) => {
e.stopPropagation();
deleteCard(card.id, el);
});
foot.append(badge, meta, del);
el.append(title, foot);
el.addEventListener('dragstart', onDragStart);
el.addEventListener('dragend', onDragEnd);
return el;
}
function render() {
for (const col of COLUMNS) {
const { list, count } = cols[col.id];
const inCol = cards.filter(c => c.status === col.id);
const shown = inCol.filter(matches);
const nodes = shown.map(buildCard);
if (!shown.length) {
const empty = document.createElement('div');
empty.className = 'empty';
empty.textContent = query ? `No cards match "${query}"` : 'Drop cards here';
nodes.push(empty);
}
list.replaceChildren(...nodes);
count.textContent = query ? `${shown.length} / ${inCol.length}` : String(inCol.length);
}
justAddedId = null;
}
// ---------- Card actions ----------
function deleteCard(id, el) {
el.classList.add('removing');
el.querySelectorAll('button').forEach(b => { b.disabled = true; });
setTimeout(() => {
cards = cards.filter(c => c.id !== id);
render();
}, 160);
}
function moveCard(id, status, beforeId) {
const idx = cards.findIndex(c => c.id === id);
if (idx < 0) return;
const [card] = cards.splice(idx, 1);
card.status = status;
let pos = beforeId !== null ? cards.findIndex(c => c.id === beforeId) : -1;
if (pos < 0) {
// Append after the last card already in the target column.
let last = -1;
cards.forEach((c, i) => { if (c.status === status) last = i; });
pos = last + 1;
}
cards.splice(pos, 0, card);
}
// ---------- Drag and drop ----------
function onDragStart(e) {
const el = e.currentTarget;
dragId = Number(el.dataset.id);
e.dataTransfer.effectAllowed = 'move';
e.dataTransfer.setData('text/plain', String(dragId));
// Defer the dimming so the browser's drag ghost stays fully opaque.
requestAnimationFrame(() => el.classList.add('dragging'));
}
function onDragEnd(e) {
e.currentTarget.classList.remove('dragging');
dragId = null;
clearDropState();
}
function clearDropState() {
indicator.remove();
for (const { section, list } of Object.values(cols)) {
section.classList.remove('over');
list.classList.remove('drop-target');
}
}
function wireColumn(section, list) {
let depth = 0; // counts nested dragenter/dragleave pairs
section.addEventListener('dragenter', (e) => {
if (dragId === null) return;
e.preventDefault();
depth++;
});
section.addEventListener('dragleave', () => {
if (dragId === null) return;
depth = Math.max(0, depth - 1);
if (depth === 0) {
section.classList.remove('over');
list.classList.remove('drop-target');
indicator.remove();
}
});
section.addEventListener('dragover', (e) => {
if (dragId === null) return;
e.preventDefault();
e.dataTransfer.dropEffect = 'move';
section.classList.add('over');
list.classList.add('drop-target');
// Find the first card whose midpoint is below the pointer.
const others = [...list.querySelectorAll('.card:not(.dragging)')];
const ref = others.find(c => {
const r = c.getBoundingClientRect();
return e.clientY < r.top + r.height / 2;
}) || null;
if (indicator.parentNode !== list || indicator.nextSibling !== ref) {
list.insertBefore(indicator, ref);
}
});
section.addEventListener('drop', (e) => {
if (dragId === null) return;
e.preventDefault();
depth = 0;
// Determine which visible card the dragged one should go in front of.
let beforeId = null;
if (indicator.parentElement === list) {
for (let el = indicator.nextElementSibling; el; el = el.nextElementSibling) {
if (el.classList.contains('card') && !el.classList.contains('dragging')) {
beforeId = Number(el.dataset.id);
break;
}
}
}
const id = dragId;
clearDropState();
moveCard(id, section.dataset.status, beforeId);
render();
});
}
// ---------- Search ----------
search.addEventListener('input', () => {
query = search.value.trim().toLowerCase();
render();
});
// ---------- Modal ----------
function openModal(status = 'todo', trigger = null) {
lastFocus = trigger || document.activeElement;
form.reset();
form.elements.status.value = status;
titleError.hidden = true;
titleInput.removeAttribute('aria-invalid');
backdrop.hidden = false;
titleInput.focus();
}
function closeModal() {
backdrop.hidden = true;
if (lastFocus && lastFocus.isConnected) lastFocus.focus();
}
newBtn.addEventListener('click', () => openModal('todo', newBtn));
cancelBtn.addEventListener('click', closeModal);
backdrop.addEventListener('mousedown', (e) => {
if (e.target === backdrop) closeModal();
});
backdrop.addEventListener('keydown', (e) => {
if (e.key !== 'Tab') return;
const items = [...form.querySelectorAll('input, select, button')];
const first = items[0];
const last = items[items.length - 1];
if (e.shiftKey && document.activeElement === first) {
e.preventDefault(); last.focus();
} else if (!e.shiftKey && document.activeElement === last) {
e.preventDefault(); first.focus();
}
});
form.addEventListener('submit', (e) => {
e.preventDefault();
const title = titleInput.value.trim();
if (!title) {
titleError.hidden = false;
titleInput.setAttribute('aria-invalid', 'true');
titleInput.focus();
return;
}
const id = nextId++;
cards.push({
id,
title,
priority: form.elements.priority.value,
status: form.elements.status.value,
});
justAddedId = id;
// Make sure the new card is visible even if a search is active.
if (query && !title.toLowerCase().includes(query)) {
search.value = '';
query = '';
}
closeModal();
render();
});
titleInput.addEventListener('input', () => {
if (titleInput.value.trim()) {
titleError.hidden = true;
titleInput.removeAttribute('aria-invalid');
}
});
// ---------- Theme ----------
themeBtn.addEventListener('click', () => {
const root = document.documentElement;
const next = root.dataset.theme === 'dark' ? 'light' : 'dark';
root.dataset.theme = next;
themeBtn.setAttribute('aria-label', `Switch to ${next === 'dark' ? 'light' : 'dark'} theme`);
});
// ---------- Global keys ----------
document.addEventListener('keydown', (e) => {
if (e.key === 'Escape' && !backdrop.hidden) {
closeModal();
return;
}
if (e.key === '/' && backdrop.hidden &&
!/INPUT|TEXTAREA|SELECT/.test(document.activeElement.tagName)) {
e.preventDefault();
search.focus();
}
});
// ---------- Init ----------
render();
})();
</script>
</body>
</html>Reasoning trace (22,761 tokens)
I'm planning a single HTML file with inline CSS and JavaScript, and I want to keep the plan lean. The requirements are three columns with counts, six pre-populated cards, and a title plus a color-coded priority badge on each card. I'm also weighing whether HTML5 drag and drop will hold up, since it tends to behave poorly on touch. I'm weighing HTML5 drag and drop against pointer-based dragging, since the native API is simpler and works well with a mouse. I'm leaning toward native drag and drop, with a dragover handler that works out the insertion index from card midpoints and shows a placeholder line. I'm settling on a drop indicator that stays in the DOM and gets moved with insertBefore as the pointer moves, instead of re-rendering the whole board on every dragover. For search, I'll filter cards by title and show the column count as visible over total while a filter is active. The board state will live in memory as a simple array, and every change will re-render from it. I'm settling the modal design: a simple overlay form with a required title, a priority select, and a default column, closed by Escape and showing an error if the title is blank. For deletion I'm skipping confirmation since the browser's confirm dialog is blocked, and I'll add a per-column add button alongside the header button. I'm setting up the six starter cards across the three columns, with two in each. Still writing the board layout and drag handlers... Still writing the drag handlers... Still working out how to reorder cards when one is dropped into a column at a specific position, since the array ordering has to stay consistent. Still working out the reorder logic: I'm writing a moveCard function that pulls the dragged card out of the array, sets its new status, and then finds where to splice it back in, using the target column's position index to place it correctly. I'm working out the drop index: it's the count of card elements before the indicator in the target list, skipping the card being dragged so the index lines up with the array after removal. I'm also keeping the dragged card in place with reduced opacity while hovering over it, rather than hiding it. I'm settling on rendering the board from state with the search filter applied, so only visible cards exist in the DOM. That way the drop index counted from the DOM lines up with the array. I'm settling on passing a `beforeId` reference instead of an index, so the drop position stays correct even when search hides some cards. The moveCard step removes the dragged card, updates its status, and splices it in before the reference card, or after the last card of that status if there is none. Now I'm thinking about how the board re-renders: a search input will trigger a full re-render, which is fine with only six cards. The drag source gets removed from the DOM on drop, so I'll make the dragend cleanup safe to run either way and let the indicator go away with the next render. Now I'm wiring the drop indicator: on dragover I'll find the first card whose midpoint is below the pointer and insert the indicator before it, or append it if there is none. Still writing the drop logic: I'm finding the reference card for the drop position by walking forward from the indicator and skipping the dragged card. Now I'm handling drop targets at the column level instead of the list, since the header and add button sit outside the list and would block drops. I'll find the first visible card after the indicator to use as the insertion reference, and I'm making sure dragover calls preventDefault and sets the drop effect to move. The dragged card's id will come from a global variable, with dataTransfer as a fallback for Firefox. I'm settling the visual styling: the dragged card drops to reduced opacity, the drop indicator is a thin glowing accent bar, and the target column gets a dashed accent border while hovered. Next I'm laying out the add-card modal, with a required title, a priority select, and a status select preset to the column it was opened from, plus focus handling on open and close. I'm settling the delete and search behavior: delete fades the card out before removing it from state, and search re-renders the board with only the visible cards and an "x of y" count. I'm also adding a placeholder for empty columns that sits outside the card list so it doesn't interfere with drop logic. I'm handling the empty-state text next: the placeholder hides while a drop is hovering over a column, and the message reads "No matching cards" during a search with no hits, otherwise "Drop cards here." Then I'll add a theme toggle that flips a data-theme attribute on the root element. I'm settling the layout: three columns once the viewport is about 760px wide, stacking to one column below that, with columns at full width on phones. Each column header gets a name, a count pill, and a colored dot, with a top border in the column's accent. Still writing the card styles: I'm setting up CSS variables for the light theme, with a background, surface, text, border and accent color. Still writing the page markup and its styles, using a light theme by default with a dark variant. Still writing the page markup: the top bar with the brand, search box, new-card and theme buttons, then the board and the add-card modal. Still writing the modal markup: a title field with a required check and error message, then priority and column selects, with Cancel and Add card buttons. Still writing the page's JavaScript: I'm defining the three columns with their names and colors, so the column elements can be built once and only their lists and counts re-rendered. Still writing the seed data: six starter cards spread across the three columns, each with a title and priority. Now I'm settling the column header: each one shows a colored dot, the column name, and a count pill, with a top border in the column's accent. Still writing the render function: I'm pulling each column's list, count, and add button from the stored references, then filling the list from the visible cards for that status. Still writing the render logic: each column's list is rebuilt from the cards matching the current search, with an empty-state message when nothing shows, and the count updates to "x of y" during a search. Still writing the card builder: each card is an article with draggable set and its id stored in a data attribute, and I'm filling its title as a paragraph. Still writing the card builder: I'm adding the priority badge, a small ID label, and a delete button that stops the click from starting a drag, then attaching the drag handlers. Still writing the removal logic: I'm animating the card out, then taking it out of the state and re-rendering the board. Still writing the drag handlers: I'm storing the dragged card's id, marking the transfer as a move, and fading the card out while it's being dragged. Still writing the drag handlers: the dragged card gets a dragging class on start, which is cleared on end along with the drop state. Still writing the column drag handlers: on dragover I'm allowing the drop and marking the column and its list as a target, then working out which card the pointer sits above so I can place the indicator there. Still working on the column drop handling: on dragover I'm making sure the indicator sits above the first card whose midpoint is below the pointer, and skipping the dragged card when I look for that reference. Still writing the column drop logic: I'm checking whether the indicator's position is stable as the pointer moves, since inserting it shifts the cards below. Still writing the drop handling: I'm checking the nearest following card so the moved card lands before it, then clearing the drop state and re-rendering the board. I'm weighing whether the dragleave handler should clear the indicator, since Chrome often reports a null relatedTarget and that would flicker it on every child boundary. A cleaner option is to check the pointer's coordinates against the column's rectangle and only clear when it actually leaves. I'm weighing a counter-based approach for the column drag-leave handler instead of checking coordinates, since Chrome's relatedTarget is unreliable during drags. Each column will track nested enter and leave events and only clear the indicator once the count drops back to zero. Next I'm wiring up the modal's open logic, where the status comes in as a preset and the element that opened it is remembered so focus can return there later. Wiring up the modal's form submit and reset path now, with the status preset and focus returning to the trigger. Still writing the submit handler: I'm trimming the title, showing the error and focusing the field if it's empty, otherwise pushing the new card into state with its priority and status and marking it as just added. Still writing the search wiring: I'm reading the query on each input and re-rendering, and I'm considering a "/" shortcut to jump into the search box. Still writing the theme toggle: on click I'm flipping the data-theme attribute on the root between dark and light, and I'm swapping the sun and moon icons with CSS so no extra logic is needed. Still writing the styles: I'm adding a dashed accent outline and light tint for a column that's a drop target, then a highlight animation for newly added cards and a fade-out for removed ones. Next is the drop indicator's look, a thin accent bar with a soft glow. Still writing the styles: I'm giving the drop indicator a thin accent bar with a soft glow, and the card list a flex column with a gap and minimum height. For an empty column I'm adding a centered dashed placeholder that hides while the column is a drop target. Still writing the board layout: a three-column grid that collapses to one column on narrow screens, with each column getting a rounded background and a minimum height. Still writing the stylesheet: I'm setting the header's font and count pills, then the priority badges with their dark and light colors, and starting on the button styles. Still writing the styles: the buttons get a bordered surface look with a solid accent variant, and a dashed full-width add button inside each column. Cards are surface-colored with a soft border and grab cursor, and I'm laying out their footer with the metadata on the left. Still writing the modal styles: a fixed dim backdrop with a centered, rounded surface, then the inputs and labels, with the error text in red. Still writing the stylesheet: I'm adding the wrap for the header and tool row, a narrow-screen layout that stacks the search field, and the full-page base styles. Next up is the HTML head and the document shell. Still writing the stylesheet's root variables: background, surface, text and border colors, plus the accent and shadow values, with the priority badge colors starting to come in. Still writing the theme variables: the dark palette sets the background, surface and accent colors, and I'm starting on the low-priority badge tint. Still writing the stylesheet's dark theme: the color-variable overrides, the badge tints and the danger color. Still writing the topbar styles: a sticky bar with wrapping flex layout, a surface background and bottom border, then the brand block and logo tile. Still writing the stylesheet: the search field gets a fixed width with a left-side icon, and inputs get a focus ring in the accent color. Still writing the button and focus styles for the toolbar. Still writing the stylesheet: I'm adding the open-column highlight, a dashed accent border with a tinted background for a column that's a drop target. Still writing the stylesheet: the column header lays out a colored dot, a title and a count pill, and I'm sizing the count with a rounded fill. Still writing the card styles: rounded surface cards with a soft border and shadow, grab cursor, and no text selection while dragging. Still writing the card styles: the hover-free drag states, a fading and shrinking removal, a flash animation for new cards, and the title and footer with the badge. Still writing the badge and button styles: the priority badges get their colors, then icon buttons turn red on hover, and the dashed add button gets a hover state. Next I'm weighing whether the drop indicator's negative margin is needed to keep the gap intact. Still writing the modal styles: a dimmed fixed backdrop and a centered rounded dialog, then the field labels and inputs, with invalid fields showing a red border and a two-column row next. Still writing the stylesheet: the narrow-screen media query stacks the board into one column and shrinks the padding, hides the project label, and lets the search field span the full row. Still writing the topbar: a sticky header with the brand block, and I'm wrapping the tools row so the search field drops to its own full-width line on narrow screens. Still writing the HTML: I'm adding the search box with its icon, the new-card button, and the theme toggle with its sun and moon icons inside the tools row. Still writing the modal form: a title field with a max length, then a priority dropdown alongside the next field in a two-column row. Still writing the modal form: the priority and column dropdowns sit side by side, then the cancel and add buttons at the bottom. Still writing the JavaScript: I'm setting up the card data, column list, and the state for search, drag, and the just-added card. Still writing the JavaScript: I'm building the column sections with their headers, dots and count pills in a loop over the column list. Still writing the board: each column gets a header with a colored dot, a title and a count pill, a list for its cards, and an add button at the bottom. Still writing the column wiring: I'm adding a drag-enter counter so the column only resets once the pointer fully leaves it, not when it crosses a child element. Still writing the column drag logic: I'm handling the drag-enter counter, and I'm weighing whether to reset it on drop or dragend, leaning toward a shared value on the section so it's cleared in one place. Next I'm settling the drop handling: the drag-enter counter gets reset to zero inside the drop handler, since that handler shares the closure with the counter. If a drag is cancelled outside the board, the leave events should bring the count back to zero on their own, so that case should be fine. Still writing the drop handler: I'm wiring the drop so it clears the drag state, moves the card into this column before whichever card sits under the indicator, and re-renders. Still writing the drop handling: I'm checking that the indicator is actually inside this column's list before using it as the insertion point, and falling back to no specific position if it isn't. Dragging from outside the board, where there's no card being dragged, gets ignored. Still writing the move logic: it removes the dragged card and sets its new status, then looks up the card it should land before, and if that card isn't found it falls back to the end of the column. Still writing the move logic: after the dragged card is removed and given its new status, I'm looking for the card it should sit before, and if that isn't found it goes to the end of the column. Still writing the render pass: for each column I filter the cards by status and the search query, then rebuild the list, with an empty-state message when nothing shows, and update the count. Still writing the delete handler: I'm marking the card as removing and disabling its buttons, then filtering it out of the array after a short delay. Still writing the modal logic: I'm saving the element that opened the dialog so focus can return to it, resetting the form, and setting the status field to the column that was clicked. Still writing the modal logic: the dialog's invalid-state reset and focus go to the title input, and I'm adding a small Tab handler that keeps focus cycling within the form. Still writing the modal's focus trap and backdrop click-to-close, and I'm starting the global Escape key handler. Still writing the keyboard shortcuts: the global Escape handler closes the modal when it's open, and the "/" key focuses the search field when no dialog is up and no form field has focus. Still writing the theme toggle: it flips the root's theme between dark and light, and I'm updating the button's label to name the theme it will switch to next. Still writing the drag cleanup: clearing the drop state removes the indicator and the highlight classes from every column, and the dragend handler resets the drag id and the dragging class. Still writing the search and count logic: I'm checking the card text against the query, and when a query is active the count shows matches over the total in the column. Still writing the icons: the delete button gets its × character, and I'm drawing the moon outline for the theme toggle. Still writing the icons: the sun and moon SVGs for the theme toggle, and the logo letter sits in the header. Still writing the stylesheet details: the header and headings get their default margins reset, and the page title's font size is overridden to fit the layout.