Image Classifier

Image classifier built with tensorgrad, running in your browser on WebGPU. Drop in photos, fix wrong guesses, and add new classes, live.

---
format: typebulb/v1
name: Image Classifier
---

**code.tsx**

```tsx
import {
  Module, Conv2d, Linear, LayerNorm, compileForward, compile, loadSafetensors,
  add, mul, matmul, swapAxes, reshape, concat, narrow, split,
  splitHeads, mergeHeads, softmax, gelu, crossEntropy, checkWebGPU, type Tensor,
} from 'tensorgrad'
import {
  App, Component, div, h1, h3, p, span, button, img, label, input, inputText, svg, polyline, polygon,
} from 'domeleon'

// ============================================================================
//  Model & feature extraction (pure logic)
// ============================================================================

// ViT-tiny dimensions (timm vit_tiny_patch16_224).
const D = 192
const H = 3
const HEADDIM = D / H
const DEPTH = 12
const PATCH = 16
const GRID = 14
const NPATCH = GRID * GRID
const NPOS = NPATCH + 1
const FFN = 4 * D
const IMG = GRID * PATCH

// timm augreg ViT preprocessing.
const MEAN = [0.5, 0.5, 0.5]
const STD = [0.5, 0.5, 0.5]

// Assets: weights on a Cloudflare R2 custom domain (cached in-browser); images
// from a public ImageNet sample set.
const R2 = 'https://assets.typebulb.com'
const WEIGHTS = `${R2}/weights/vit_tiny_patch16_224.augreg_in21k_ft_in1k.safetensors`
const IMG_BASE = 'https://raw.githubusercontent.com/EliSchwartz/imagenet-sample-images/master/'
const HELDOUT = `${IMG_BASE}n02123597_Siamese_cat.JPEG`   // not in the seed set — the launch image, to show generalization

const PALETTE = ['#e8833a', '#3a7de8', '#34a853', '#a142f4', '#e0457b', '#00897b', '#f4b400', '#5f6368']

const SEED = [
  ['cat', 'n02123045_tabby.JPEG'], ['cat', 'n02123159_tiger_cat.JPEG'], ['cat', 'n02123394_Persian_cat.JPEG'], ['cat', 'n02124075_Egyptian_cat.JPEG'],
  ['dog', 'n02110185_Siberian_husky.JPEG'], ['dog', 'n02109961_Eskimo_dog.JPEG'], ['dog', 'n02099601_golden_retriever.JPEG'], ['dog', 'n02099712_Labrador_retriever.JPEG'],
  ['car', 'n02814533_beach_wagon.JPEG'], ['car', 'n03100240_convertible.JPEG'], ['car', 'n04285008_sports_car.JPEG'], ['car', 'n03594945_jeep.JPEG'],
].map(([label, file]) => ({ label: label!, file: file!, url: IMG_BASE + file }))

interface Example { feat: Float32Array; label: number; url: string }
interface Shot { url: string; feat: Float32Array | null }

// First load fetches from R2; reloads/revisits hit CacheStorage.
async function cachedFetch(url: string): Promise<ArrayBuffer> {
  const cache = await caches.open('tensorgrad-assets')
  let res = await cache.match(url)
  if (!res) {
    res = await fetch(url)
    // Best-effort: a failed/partial cache write shouldn't break the load.
    if (res.ok) {
      try { await cache.put(url, res.clone()) } catch { /* caching is an optimization */ }
    }
  }
  if (!res.ok) throw new Error(`fetch ${url} -> ${res.status}`)
  return res.arrayBuffer()
}

function loadImage(src: string, cors = false): Promise<HTMLImageElement> {
  const image = new Image()
  if (cors) image.crossOrigin = 'anonymous'   // cross-origin sources must be CORS-loaded or the canvas taints
  return new Promise((res, rej) => {
    image.onload = () => res(image)
    image.onerror = () => rej(new Error('image load failed'))
    image.src = src
  })
}

// Center-crop to IMG×IMG, normalize, and lay out as CHW for the backbone.
function imageTensor(image: HTMLImageElement): Float32Array {
  const canvas = document.createElement('canvas')
  canvas.width = IMG
  canvas.height = IMG
  const ctx = canvas.getContext('2d')!
  const w = image.naturalWidth || image.width
  const h = image.naturalHeight || image.height
  const side = Math.min(w, h)
  ctx.drawImage(image, (w - side) / 2, (h - side) / 2, side, side, 0, 0, IMG, IMG)

  const px = ctx.getImageData(0, 0, IMG, IMG).data
  const x = new Float32Array(3 * IMG * IMG)
  for (let i = 0; i < IMG * IMG; i++) {
    for (let ch = 0; ch < 3; ch++) {
      x[ch * IMG * IMG + i] = (px[i * 4 + ch]! / 255 - MEAN[ch]!) / STD[ch]!
    }
  }
  return x
}

function l2normalize(v: Float32Array): Float32Array {
  let norm = 0
  for (const x of v) norm += x * x
  norm = Math.sqrt(norm) || 1
  const out = new Float32Array(v.length)
  for (let i = 0; i < v.length; i++) out[i] = v[i]! / norm
  return out
}

// ---- ViT-tiny, features only (no classifier head) ----

class Block extends Module {
  norm1 = new LayerNorm(D)
  qkv = new Linear(D, 3 * D)
  proj = new Linear(D, D)
  norm2 = new LayerNorm(D)
  fc1 = new Linear(D, FFN)
  fc2 = new Linear(FFN, D)
}

class ViT extends Module {
  patch = new Conv2d(3, D, PATCH, { stride: PATCH })
  cls = this.param([1, 1, D])
  pos = this.param([1, NPOS, D])
  norm = new LayerNorm(D)
  blocks: Block[]

  constructor() {
    super()
    this.blocks = Array.from({ length: DEPTH }, () => new Block())
  }
}

function block(b: Block, x: Tensor): Tensor {
  const [q0, k0, v0] = split(b.qkv.fwd(b.norm1.fwd(x)), [D, D, D], -1)
  const q = splitHeads(q0, H)
  const k = splitHeads(k0, H)
  const v = splitHeads(v0, H)
  const scores = mul(matmul(q, swapAxes(k, -1, -2)), 1 / Math.sqrt(HEADDIM))
  const attended = mergeHeads(matmul(softmax(scores, -1), v))
  const x1 = add(x, b.proj.fwd(attended))
  return add(x1, b.fc2.fwd(gelu(b.fc1.fwd(b.norm2.fwd(x1)))))
}

// Patchify -> prepend cls token -> add positions -> blocks -> the cls feature [1, D].
function embed(m: ViT, { x }: { x: Tensor }): Tensor {
  let h = swapAxes(reshape(m.patch.fwd(x), [1, D, NPATCH]), 1, 2)
  h = add(concat([m.cls, h], 1), m.pos)
  for (const b of m.blocks) h = block(b, h)
  return reshape(narrow(m.norm.fwd(h), 1, 0, 1), [1, D])
}

function transpose2d(s: Float32Array, rows: number, cols: number): Float32Array {
  const out = new Float32Array(rows * cols)
  for (let r = 0; r < rows; r++) {
    for (let c = 0; c < cols; c++) out[c * rows + r] = s[r * cols + c]!
  }
  return out
}

// Map the timm checkpoint keys onto this Module's param names, transposing every
// Linear ([out, in] -> [in, out]). uploadParams is strict, so this must cover
// every backbone param; head.* is intentionally omitted (features only).
function importViT(t: Record<string, Float32Array>, shapes: Record<string, number[]>): Record<string, Float32Array> {
  const out: Record<string, Float32Array> = {}
  const T = (n: string) => transpose2d(t[n]!, shapes[n]![0]!, shapes[n]![1]!)

  out['patch.W'] = t['patch_embed.proj.weight']!
  out['patch.b'] = t['patch_embed.proj.bias']!
  out['cls'] = t['cls_token']!
  out['pos'] = t['pos_embed']!
  out['norm.g'] = t['norm.weight']!
  out['norm.b'] = t['norm.bias']!

  for (let i = 0; i < DEPTH; i++) {
    const s = `blocks.${i}`
    out[`${s}.norm1.g`] = t[`${s}.norm1.weight`]!
    out[`${s}.norm1.b`] = t[`${s}.norm1.bias`]!
    out[`${s}.qkv.W`] = T(`${s}.attn.qkv.weight`)
    out[`${s}.qkv.b`] = t[`${s}.attn.qkv.bias`]!
    out[`${s}.proj.W`] = T(`${s}.attn.proj.weight`)
    out[`${s}.proj.b`] = t[`${s}.attn.proj.bias`]!
    out[`${s}.norm2.g`] = t[`${s}.norm2.weight`]!
    out[`${s}.norm2.b`] = t[`${s}.norm2.bias`]!
    out[`${s}.fc1.W`] = T(`${s}.mlp.fc1.weight`)
    out[`${s}.fc1.b`] = t[`${s}.mlp.fc1.bias`]!
    out[`${s}.fc2.W`] = T(`${s}.mlp.fc2.weight`)
    out[`${s}.fc2.b`] = t[`${s}.mlp.fc2.bias`]!
  }
  return out
}

// A one-layer head over the frozen 192-d features, trained with crossEntropy + Adam.
class Head extends Module {
  fc: Linear
  constructor(classes: number) {
    super()
    this.fc = new Linear(D, classes)
  }
}

async function trainHead(train: Example[], classes: number) {
  const N = train.length
  const feats = new Float32Array(N * D)
  train.forEach((e, i) => feats.set(e.feat, i * D))
  const labels = Int32Array.from(train.map(e => e.label))

  const head = await compile({
    model: new Head(classes),
    loss: (m: Head, { f, y }: { f: Tensor; y: Tensor }) => crossEntropy(m.fc.fwd(f), y),
    inputs: { f: [N, D], y: { shape: [N], dtype: 'i32' } },
    optimizer: { kind: 'adam', lr: 0.05 },
  })

  const losses: number[] = []
  for (let step = 0; step < 200; step++) {
    const r = await head.step({ f: feats.slice(), y: labels.slice() })
    if (r.kind !== 'completed') break
    losses.push(r.loss)
  }

  const infer = await head.attach({
    forward: (m: Head, { f }: { f: Tensor }) => softmax(m.fc.fwd(f), -1),
    inputs: { f: [1, D] },
  })
  return { head, infer, losses }
}

// ============================================================================
//  Model — app state + the ML pipeline (a non-visual domeleon component)
// ============================================================================

class Model extends Component {
  status = 'starting…'
  ready = false                          // backbone loaded + head trained at least once
  retraining = false
  classes: string[] = ['cat', 'dog', 'car']
  train: Example[] = []
  losses: number[] = []
  shot: Shot | null = null               // the image currently classified in the stage
  probs: Float32Array | null = null

  #backbone: Awaited<ReturnType<typeof compileForward<ViT, { x: number[] }>>> | null = null
  #trained: Awaited<ReturnType<typeof trainHead>> | null = null
  // Snapshots of the initial state, so reset() starts over from cached features.
  #seedClasses: string[] = []
  #seedTrain: Example[] = []
  #initialShot: { url: string; feat: Float32Array } | null = null
  #started = false

  override onAttached() {
    if (this.#started) return
    this.#started = true
    this.start()
  }

  setStatus(s: string) {
    this.status = s
    tb.log(s)
    this.update()
  }

  async start() {
    const gpu = await checkWebGPU()
    if (!gpu.ok) {
      this.setStatus(gpu.message)
      return
    }

    this.setStatus('Loading the model…')
    const { tensors, shapes } = loadSafetensors(await cachedFetch(WEIGHTS))
    this.#backbone = await compileForward({ model: new ViT(), forward: embed, inputs: { x: [1, 3, IMG, IMG] } })
    await this.#backbone.uploadParams(importViT(tensors, shapes))

    // Extract the seed features once, then snapshot them for reset().
    for (let i = 0; i < SEED.length; i++) {
      this.setStatus(`Extracting features ${i + 1}/${SEED.length}…`)
      const feat = await this.embOf(await loadImage(SEED[i]!.url, true))
      this.train.push({ feat, label: this.classes.indexOf(SEED[i]!.label), url: SEED[i]!.url })
      this.update()
    }
    this.#seedClasses = [...this.classes]
    this.#seedTrain = this.train.map(e => ({ ...e }))

    this.setStatus('Training the head…')
    await this.retrain()
    await this.preselect()
    tb.log('Ready.')
  }

  async embOf(image: HTMLImageElement): Promise<Float32Array> {
    const r = await this.#backbone!.run({ x: imageTensor(image) })
    if (r.kind !== 'completed') throw new Error(`embed run ${r.kind}`)
    return l2normalize(r.output as Float32Array)
  }

  async retrain() {
    this.retraining = true
    this.update()
    this.#trained?.head.destroy()
    this.#trained = await trainHead(this.train, this.classes.length)
    this.losses = this.#trained.losses
    this.ready = true
    this.retraining = false
    this.status = ''
    if (this.shot?.feat) await this.classify()
    else this.update()
  }

  // Start over from the cached seed set — no refresh, no re-embedding.
  async reset() {
    this.classes = [...this.#seedClasses]
    this.train = this.#seedTrain.map(e => ({ ...e }))
    this.shot = this.#initialShot ? { ...this.#initialShot } : null
    this.probs = null
    await this.retrain()
  }

  async classify() {
    if (!this.#trained || !this.shot?.feat) return
    const r = await this.#trained.infer.run({ f: this.shot.feat })
    if (r.kind !== 'completed') {
      tb.log(`classify ${r.kind}`)
      return
    }
    this.probs = r.output as Float32Array
    this.update()
  }

  // Click a training thumbnail. Its feature is cached, so classify is instant —
  // keep the previous bars on screen (they animate to the new values) rather than
  // collapsing to the "reading" state, which would cause a height blink.
  async selectShot(url: string, feat: Float32Array) {
    this.shot = { url, feat }
    this.update()
    await this.classify()
  }

  // Drop / choose a file: show it at once, embed with the frozen backbone, classify.
  async onPick(file: File) {
    if (!this.ready) return
    try {
      const url = URL.createObjectURL(file)
      const image = await loadImage(url)
      this.shot = { url, feat: null }
      this.probs = null
      this.update()
      const feat = await this.embOf(image)
      if (this.shot) this.shot.feat = feat
      await this.classify()
    } catch (err) {
      tb.log(`couldn't read image: ${(err as Error).message}`)
    }
  }

  async teachInto(ci: number) {
    if (!this.shot?.feat) return
    this.train.push({ feat: this.shot.feat, label: ci, url: this.shot.url })
    await this.retrain()
  }

  async teachNewClass(name: string) {
    if (!this.shot?.feat) return
    this.classes.push(name)
    this.train.push({ feat: this.shot.feat, label: this.classes.length - 1, url: this.shot.url })
    await this.retrain()
  }

  // Classify a held-out image (not in the seed set) on launch, to show real
  // generalization; fall back to the first seed if it fails to load.
  async preselect() {
    try {
      this.shot = { url: HELDOUT, feat: null }
      this.update()
      const feat = await this.embOf(await loadImage(HELDOUT, true))
      if (this.shot) this.shot.feat = feat
      this.#initialShot = { url: HELDOUT, feat }
      await this.classify()
    } catch {
      const e = this.train[0]
      if (e) {
        this.#initialShot = { url: e.url, feat: e.feat }
        await this.selectShot(e.url, e.feat)
      }
    }
  }
}

// ============================================================================
//  UI
// ============================================================================

const classColor = (i: number) => PALETTE[i % PALETTE.length]!

class Root extends Component {
  model = new Model()

  // View-local state for the inline "new class" editor.
  dragOver = false
  addingClass = false
  newClassName = ''
  #outsideHandler: ((e: MouseEvent) => void) | null = null

  // --- delegating handlers (close the editor, then act on the model) ---

  pick(file: File) {
    this.cancelNewClass()
    this.model.onPick(file)
  }
  select(url: string, feat: Float32Array) {
    this.cancelNewClass()
    this.model.selectShot(url, feat)
  }
  reset() {
    this.cancelNewClass()
    this.model.reset()
  }

  // --- inline "new class" editor ---

  startNewClass() {
    this.addingClass = true
    this.newClassName = ''
    this.update()
    this.armOutsideClose()
  }
  cancelNewClass() {
    this.disarmOutsideClose()
    if (!this.addingClass && !this.newClassName) return
    this.addingClass = false
    this.newClassName = ''
    this.update()
  }
  confirmNewClass() {
    const name = this.newClassName.trim()
    if (!name) return
    this.disarmOutsideClose()
    this.addingClass = false
    this.newClassName = ''
    this.model.teachNewClass(name)
  }
  armOutsideClose() {
    this.disarmOutsideClose()
    this.#outsideHandler = (e: MouseEvent) => {
      if ((e.target as Element | null)?.closest('.newclass-form')) return   // click inside — keep it open
      this.cancelNewClass()
    }
    // Defer so the click that opened the editor doesn't immediately close it.
    setTimeout(() => { if (this.#outsideHandler) document.addEventListener('click', this.#outsideHandler) }, 0)
  }
  disarmOutsideClose() {
    if (!this.#outsideHandler) return
    document.removeEventListener('click', this.#outsideHandler)
    this.#outsideHandler = null
  }

  view() {
    return div(
      div({ class: 'header' },
        h1('Image Classifier'),
        this.chartSection(),
      ),
      this.stage(),
      this.trainingSet(),
      this.about(),
    )
  }

  // --- stage: the hero card (drop bar + classified image + readout) ---

  stage() {
    if (!this.model.ready) {
      return div({ class: 'stage' }, this.loading())
    }
    return div({
      class: 'stage',
      onDragOver: (e: DragEvent) => { e.preventDefault(); if (!this.dragOver) { this.dragOver = true; this.update() } },
      onDragLeave: () => { if (this.dragOver) { this.dragOver = false; this.update() } },
      onDrop: (e: DragEvent) => {
        e.preventDefault()
        this.dragOver = false
        this.update()
        const f = e.dataTransfer?.files?.[0]
        if (f) this.pick(f)
      },
    },
      this.dropBar(),
      this.model.shot ? this.result() : null,
    )
  }

  loading() {
    return div({ class: 'loading' },
      p({ class: 'loading-lead' }, 'This pretrained vision model runs entirely in your browser, on your GPU.'),
      div({ class: 'loading-status' }, span({ class: 'spinner' }), span(this.model.status || 'Warming up…')),
    )
  }

  fileInput() {
    return input({
      type: 'file',
      accept: 'image/*',
      class: 'fileinput',
      onChange: (e: Event) => {
        const f = (e.target as HTMLInputElement).files?.[0]
        if (f) this.pick(f)
      },
    })
  }

  dropBar() {
    return label({ class: ['dropbar', this.dragOver ? 'over' : ''] },
      span({ class: 'dropbar-plus' }, '+'),
      span('Drop an image here, or click to choose'),
      this.fileInput(),
    )
  }

  result() {
    return div({ class: 'result' },
      img({ src: this.model.shot!.url, class: 'shot-img' }),
      this.readout(),
    )
  }

  readout() {
    const { probs, classes } = this.model
    if (!probs) {
      return div({ class: 'readout' },
        div({ class: 'readout-wait' }, span({ class: 'spinner' }), 'reading the image…'),
      )
    }
    let pred = 0
    for (let i = 1; i < probs.length; i++) if (probs[i]! > probs[pred]!) pred = i

    return div({ class: 'readout' },
      div({ class: 'verdict' },
        span({ class: 'verdict-class', style: { color: classColor(pred) } }, classes[pred]!),
        span({ class: 'verdict-pct' }, `${(probs[pred]! * 100).toFixed(0)}% confident`),
      ),
      div({ class: 'bars' }, classes.map((name, ci) => this.bar(name, ci, probs[ci]!))),
      this.teach(),
    )
  }

  bar(name: string, ci: number, prob: number) {
    return div({ class: 'bar' },
      span({ class: 'barlab' }, name),
      div({ class: 'track' },
        div({ class: 'fill', style: { width: `${(prob * 100).toFixed(1)}%`, background: classColor(ci) } }),
      ),
      span({ class: 'barpct' }, `${(prob * 100).toFixed(0)}%`),
    )
  }

  teach() {
    return div({ class: 'teach' },
      span({ class: 'teach-lbl' }, 'Not quite? Teach it — add this image to:'),
      div({ class: 'teach-btns' },
        this.model.classes.map((name, ci) =>
          button({
            class: 'teach-btn',
            style: { borderColor: classColor(ci), color: classColor(ci) },
            onClick: () => this.model.teachInto(ci),
          }, name)),
        this.addingClass ? this.newClassEditor() : this.newClassButton(),
      ),
    )
  }

  newClassButton() {
    return button({ class: ['teach-btn', 'newclass'], onClick: () => this.startNewClass() }, '+ new class')
  }

  newClassEditor() {
    return div({ class: 'newclass-form' },
      inputText({
        target: this,
        prop: () => this.newClassName,
        attrs: {
          placeholder: 'New class name',
          class: 'newclass-input',
          onMounted: (el: Element) => (el as HTMLInputElement).focus(),
          onKeyDown: (e: KeyboardEvent) => {
            if (e.key === 'Enter') this.confirmNewClass()
            else if (e.key === 'Escape') this.cancelNewClass()
          },
        },
      }),
      button({ class: 'teach-btn', onClick: () => this.confirmNewClass() }, 'Add'),
    )
  }

  // --- training-loss chart ---

  chartSection() {
    const { losses, retraining } = this.model
    if (!losses.length) return null
    const first = losses[0]!
    const last = losses.at(-1)!
    return div({ class: 'chartrow' },
      this.chart(),
      div({ class: 'chart-label' },
        span({ class: 'chart-label-title' }, 'training loss'),
        span({ class: 'chart-label-num' }, retraining ? 'retraining…' : `${first.toFixed(2)} → ${last.toFixed(3)}`),
      ),
    )
  }

  // Filled area curve, full-bleed. Loss starts high (top-left) and falls to the
  // floor; the empty upper-right is where the label overlays.
  chart() {
    const losses = this.model.losses
    if (losses.length < 2) return null
    const W = 600
    const Hh = 150
    const topPad = 12
    const max = Math.max(...losses)
    const min = Math.min(...losses)
    const rng = max - min || 1
    const x = (i: number) => i / (losses.length - 1) * W
    const y = (l: number) => topPad + (max - l) / rng * (Hh - topPad)
    const line = losses.map((l, i) => `${x(i).toFixed(1)},${y(l).toFixed(1)}`).join(' ')
    const area = `0,${Hh} ${line} ${W},${Hh}`
    return svg({ class: 'chart', viewBox: `0 0 ${W} ${Hh}`, preserveAspectRatio: 'none' },
      polygon({ points: area, fill: 'color-mix(in srgb, var(--accent) 18%, transparent)', stroke: 'none' }),
      polyline({ points: line, fill: 'none', stroke: 'var(--accent)', strokeWidth: 1.5, vectorEffect: 'non-scaling-stroke' }),
    )
  }

  // --- training set ---

  trainingSet() {
    return div({ class: 'training' },
      div({ class: 'training-head' },
        h3('Training set'),
        this.model.ready ? button({ class: 'reset-btn', onClick: () => this.reset() }, 'Reset') : null,
      ),
      div({ class: 'gallery' }, this.model.classes.map((name, ci) => this.classColumn(name, ci))),
    )
  }

  classColumn(name: string, ci: number) {
    const thumbs = this.model.train.filter(e => e.label === ci)
    return div({ class: 'classcol' },
      div({ class: 'classlbl', style: { color: classColor(ci) } }, name),
      div({ class: 'strip' }, thumbs.map(e =>
        img({
          src: e.url,
          class: ['thumb', this.model.shot?.url === e.url ? 'selected' : ''],
          style: { borderColor: classColor(ci) },
          onClick: () => this.select(e.url, e.feat),
        }))),
    )
  }

  about() {
    return div({ class: 'about' },
      p('This is a pretrained image classifier running in your browser with tensorgrad. On startup, we train the model to recognize 3 categories based on the 12 images. You can continue to train the model by adding your own images and classifying them.'),
      p('Under the hood the pretrained model is a frozen ViT-tiny that turns each image into a 192-dimensional feature vector. tensorgrad trains a one-layer head on top of those features, so the backbone never changes and only the head learns.'),
    )
  }
}

new App({ root: new Root(), id: 'app' })
```
**styles.css**

```css
:root {
  --bg: rgb(255, 255, 255);
  --fg: rgb(28, 28, 30);
  --muted: rgb(82, 84, 92);
  --panel: rgb(252, 252, 253);
  --border: rgb(224, 224, 228);
  --accent: rgb(58, 125, 232);
  --track: rgb(233, 234, 238);
  --thumb-hover-shadow: 0 0 14px rgba(0, 0, 0, .8);
}

html[data-theme="dark"] {
  --bg: rgb(22, 22, 24);
  --fg: rgb(232, 232, 236);
  --muted: rgb(150, 152, 160);
  --panel: rgb(32, 32, 38);
  --border: rgb(58, 58, 64);
  --accent: rgb(122, 162, 250);
  --track: rgb(48, 48, 54);
  --thumb-hover-shadow: 0 0 16px rgba(255, 255, 255, .28);
}

body {
  max-width: 960px;
  margin: 1.5rem auto 2rem;
  padding: 0 1.25rem;
  color: var(--fg);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

h1 {
  font-size: 2.3rem;
  font-weight: 650;
  line-height: 1.15;
  margin: 0;
  letter-spacing: -0.01em;
}

h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 0;
  text-transform: uppercase;
  letter-spacing: .05em;
}

/* header row — title beside the loss sparkline (stacks on mobile) */
.header {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  margin-bottom: 1.35rem;
}

/* hero stage card */
.stage {
  border: 1px solid var(--border);
  background: var(--panel);
  border-radius: 14px;
  margin-bottom: 2rem;
}

/* loss sparkline — bare, fills the width beside the title */
.chartrow {
  position: relative;
  overflow: hidden;
  flex: 1;
  min-width: 0;
}

.chart {
  width: 100%;
  height: 52px;
  display: block;
}

.chart-label {
  position: absolute;
  top: .55rem;
  right: .9rem;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: .05rem;
  pointer-events: none;
}

.chart-label-title {
  font-weight: 600;
  font-size: .9rem;
}

.chart-label-num {
  font-size: .8rem;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

/* stage — the hero card */
.stage { padding: 1.25rem; }

.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  padding: 1.75rem 1rem;
  text-align: center;
}

.loading-lead {
  margin: 0;
  color: var(--fg);
  font-size: 1.05rem;
  line-height: 1.5;
}

.loading-status {
  display: flex;
  align-items: center;
  gap: .7rem;
  color: var(--muted);
  font-size: .95rem;
}

.dropbar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: .5rem;
  padding: .7rem 1rem;
  margin-bottom: 1.25rem;
  border: 2px dashed var(--border);
  border-radius: 10px;
  color: var(--muted);
  font-size: .95rem;
  cursor: pointer;
  transition: border-color .15s, color .15s, background .15s;
}

.dropbar:hover,
.dropbar.over {
  border-color: var(--accent);
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 7%, var(--panel));
}

.dropbar-plus {
  font-size: 1.2rem;
  font-weight: 300;
  line-height: 1;
}

.fileinput { display: none; }

.result {
  display: flex;
  gap: 1.75rem;
  align-items: flex-start;
  flex-wrap: wrap;
}

.shot-img {
  width: 240px;
  height: 240px;
  object-fit: cover;
  border-radius: 12px;
  display: block;
  box-shadow: 0 1px 5px rgba(0, 0, 0, .14);
}

.readout {
  flex: 1;
  min-width: 280px;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.readout-wait {
  display: flex;
  align-items: center;
  gap: .6rem;
  color: var(--muted);
  padding-top: 1rem;
}

.verdict {
  display: flex;
  align-items: baseline;
  gap: .6rem;
}

.verdict-class {
  font-size: 2rem;
  font-weight: 680;
  letter-spacing: -0.01em;
  text-transform: capitalize;
}

.verdict-pct {
  font-size: 1.05rem;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.bars {
  display: flex;
  flex-direction: column;
  gap: .5rem;
}

.bar {
  display: flex;
  align-items: center;
  gap: .7rem;
}

.barlab {
  width: 84px;
  text-align: right;
  color: var(--muted);
  text-transform: capitalize;
}

.track {
  flex: 1;
  height: 18px;
  background: var(--track);
  border-radius: 9px;
  overflow: hidden;
}

.fill {
  height: 100%;
  border-radius: 9px;
  transition: width .3s ease;
}

.barpct {
  width: 40px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.teach {
  display: flex;
  flex-direction: column;
  gap: .5rem;
  margin-top: .25rem;
}

.teach-lbl {
  color: var(--muted);
  font-size: .95rem;
}

.teach-btns {
  display: flex;
  gap: .5rem;
  flex-wrap: wrap;
}

.teach-btn {
  font-size: .95rem;
  line-height: 1;
  font-family: inherit;
  background: var(--panel);
  border: 1.5px solid var(--border);
  border-radius: 8px;
  padding: .35rem .8rem;
  cursor: pointer;
  text-transform: capitalize;
  transition: background .12s;
}

.teach-btn:hover { background: color-mix(in srgb, var(--fg) 6%, var(--panel)); }

.teach-btn.newclass {
  border-style: dashed;
  color: var(--muted);
  text-transform: none;
}

.newclass-form {
  display: inline-flex;
  gap: .4rem;
  align-items: center;
}

.newclass-input {
  font: inherit;
  font-size: .95rem;
  padding: .35rem .6rem;
  border: 1.5px solid var(--accent);
  border-radius: 8px;
  background: var(--panel);
  color: var(--fg);
  width: 11rem;
}

.newclass-input:focus {
  outline: none;
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent);
}

/* training set */
.training { margin-bottom: 2rem; }

.training-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1rem;
}

.reset-btn {
  font-family: inherit;
  font-size: .9rem;
  background: var(--panel);
  border: 1.5px solid var(--border);
  border-radius: 8px;
  padding: .3rem .8rem;
  cursor: pointer;
  color: var(--muted);
  transition: border-color .12s, color .12s;
}

.reset-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.gallery {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem 1.75rem;
}

.classcol {
  display: flex;
  flex-direction: column;
  gap: .5rem;
}

.classlbl {
  font-weight: 600;
  text-transform: capitalize;
}

.strip {
  display: flex;
  gap: 8px;
  flex-wrap: nowrap;
}

.thumb {
  width: 76px;
  height: 76px;
  object-fit: cover;
  border-radius: 8px;
  border: 2px solid;
  display: block;
  cursor: pointer;
  transition: box-shadow .12s;
}

.thumb:hover { box-shadow: var(--thumb-hover-shadow); }
.thumb.selected { box-shadow: 0 0 0 3px var(--accent); }

/* about — at the bottom; functionality speaks first */
.about {
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.65;
  margin: 0;
}

.about p { margin: 0 0 .9rem; }
.about p:last-child { margin-bottom: 0; }

.spinner {
  width: 16px;
  height: 16px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  display: inline-block;
  animation: spin .8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* below ~700px the image + readout no longer sit side by side — stack them.
   The image goes fluid (capped at its 240px size) so it can shrink on narrow
   screens instead of pinning the column width and keeping the bars wide. */
@media (max-width: 700px) {
  h1 { text-align: center; }
  /* title and sparkline stack; the chart reclaims its full row (same height) */
  .header { flex-direction: column; align-items: stretch; gap: .9rem; }
  .result { flex-direction: column; }
  .shot-img {
    width: 100%;
    max-width: 240px;
    height: auto;
    aspect-ratio: 1;
    margin-inline: auto;
  }
  .readout {
    width: 100%;
    min-width: 0;
  }
  .verdict { justify-content: center; }
}

/* mobile: reclaim the page gutters and let thumbnail rows shrink to fit */
@media (max-width: 640px) {
  body { padding: 0 .6rem; }
  .gallery { gap: 1.25rem; }
  .classcol { width: 100%; }
  .strip { gap: 6px; }
  .thumb {
    flex: 1 1 0;
    min-width: 0;
    width: auto;
    height: auto;
    aspect-ratio: 1;
    max-width: 84px;
  }
  .bar { gap: .5rem; }
  .barlab { width: 60px; }
  .track { min-width: 0; }
  .barpct { width: 30px; }
}
```
**index.html**

```html
<div id="app"></div>
```
**config.json**

```json
{
  "dependencies": {
    "tensorgrad": "^0.4.6",
    "domeleon": "^0.6.3"
  },
  "description": "Image classifier built with tensorgrad, running in your browser on WebGPU. Drop in photos, fix wrong guesses, and add new classes, live."
}
```

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