:root {
  --bg: #0b0e14;
  --bg-glow: rgba(56, 189, 248, 0.10);
  --surface: #131823;
  --surface-2: #1a2130;
  --border: rgba(255, 255, 255, 0.08);
  --text: #e8edf5;
  --muted: #8b95a7;
  --track: rgba(255, 255, 255, 0.07);
  --download-a: #22d3ee;
  --download-b: #38bdf8;
  --upload-a: #a78bfa;
  --upload-b: #e879f9;
  --accent: #38bdf8;
  --danger: #f87171;
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
  --radius: 18px;
  --font: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", "Cascadia Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg: #f4f6fb;
    --bg-glow: rgba(56, 189, 248, 0.18);
    --surface: #ffffff;
    --surface-2: #eef1f7;
    --border: rgba(15, 23, 42, 0.08);
    --text: #0f172a;
    --muted: #5b6577;
    --track: rgba(15, 23, 42, 0.07);
    --download-a: #0891b2;
    --download-b: #0284c7;
    --upload-a: #7c3aed;
    --upload-b: #c026d3;
    --accent: #0284c7;
    --shadow: 0 20px 60px rgba(15, 23, 42, 0.15);
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font);
  color: var(--text);
  background:
    radial-gradient(900px 500px at 50% -10%, var(--bg-glow), transparent 70%),
    var(--bg);
  -webkit-font-smoothing: antialiased;
}

button { font: inherit; color: inherit; }

.app {
  max-width: 920px;
  margin: 0 auto;
  padding: 24px 16px 32px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ---------- Top bar ---------- */

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.1rem;
  letter-spacing: 0.01em;
}
.brand strong { font-weight: 700; }
.brand-mark { width: 28px; height: 28px; color: var(--accent); }

.client {
  font-size: 0.85rem;
  color: var(--muted);
  font-family: var(--mono);
}

/* ---------- Mode controls ---------- */

.controls {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.segmented {
  display: inline-flex;
  margin: 0;
  padding: 4px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: var(--surface);
  gap: 2px;
}
.segmented legend {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip-path: inset(50%);
}
.segmented label { position: relative; cursor: pointer; }
.segmented input {
  position: absolute;
  inset: 0;
  opacity: 0;
  margin: 0;
  cursor: inherit;
}
.segmented span {
  display: block;
  padding: 8px 18px;
  border-radius: 999px;
  font-size: 0.9rem;
  color: var(--muted);
  transition: background-color 0.2s, color 0.2s;
  white-space: nowrap;
}
.segmented input:checked + span {
  background: var(--surface-2);
  color: var(--text);
  box-shadow: inset 0 0 0 1px var(--border);
}
.segmented input:focus-visible + span { outline: 2px solid var(--accent); outline-offset: 2px; }
.segmented:disabled { opacity: 0.55; }
.segmented:disabled label { cursor: not-allowed; }

.mode-hint {
  margin: -8px 0 0;
  text-align: center;
  font-size: 0.82rem;
  color: var(--muted);
}

/* ---------- Gauge ---------- */

.stage {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}

.gauge {
  position: relative;
  width: min(360px, 86vw);
  aspect-ratio: 300 / 256; /* matches the cropped SVG viewBox */
}
.gauge svg { width: 100%; height: 100%; overflow: visible; }

.gauge-track,
.gauge-fill {
  fill: none;
  stroke-width: 18;
  stroke-linecap: round;
}
.gauge-track { stroke: var(--track); }
.gauge-fill {
  stroke: url(#grad-download);
  filter: drop-shadow(0 0 10px color-mix(in srgb, var(--download-b) 45%, transparent));
}
.gauge[data-phase="upload"] .gauge-fill {
  stroke: url(#grad-upload);
  filter: drop-shadow(0 0 10px color-mix(in srgb, var(--upload-b) 45%, transparent));
}
.s-download-a { stop-color: var(--download-a); }
.s-download-b { stop-color: var(--download-b); }
.s-upload-a { stop-color: var(--upload-a); }
.s-upload-b { stop-color: var(--upload-b); }

.gauge-tick {
  fill: var(--muted);
  font-size: 11px;
  font-family: var(--font);
  text-anchor: middle;
  dominant-baseline: middle;
  font-variant-numeric: tabular-nums;
}

/* Square box centred on the dial, overflowing the cropped gauge; clicks pass through it. */
.gauge-center {
  position: absolute;
  inset: 0 0 auto;
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  pointer-events: none;
}
.gauge-center > * { pointer-events: auto; }

.start {
  width: 46%;
  aspect-ratio: 1;
  border-radius: 50%;
  border: 2px solid color-mix(in srgb, var(--accent) 70%, transparent);
  background:
    radial-gradient(circle at 50% 35%, color-mix(in srgb, var(--accent) 22%, transparent), transparent 70%),
    var(--surface);
  font-size: clamp(1.6rem, 6vw, 2.2rem);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  cursor: pointer;
  box-shadow: 0 0 0 0 color-mix(in srgb, var(--accent) 40%, transparent);
  animation: pulse 2.4s ease-out infinite;
  transition: transform 0.15s;
}
.start:hover { transform: scale(1.04); }
.start:active { transform: scale(0.98); }
.start:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }

@keyframes pulse {
  0% { box-shadow: 0 0 0 0 color-mix(in srgb, var(--accent) 40%, transparent); }
  80%, 100% { box-shadow: 0 0 0 26px transparent; }
}

.readout {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  text-align: center;
}
.readout[hidden] { display: none; }
.readout-phase {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--muted);
}
.readout-value {
  font-size: clamp(2.6rem, 11vw, 3.6rem);
  font-weight: 700;
  line-height: 1.05;
  font-variant-numeric: tabular-nums;
}
.readout-unit { color: var(--muted); font-size: 0.95rem; }
.readout-latency {
  min-height: 1.3em;
  margin-top: 4px;
  font-size: 0.8rem;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.progress {
  width: min(320px, 80vw);
  height: 4px;
  border-radius: 4px;
  background: var(--track);
  overflow: hidden;
}
.progress-bar {
  height: 100%;
  width: 0;
  background: linear-gradient(90deg, var(--download-a), var(--download-b));
  transition: width 0.15s linear;
}
.gauge[data-phase="upload"] ~ .progress .progress-bar {
  background: linear-gradient(90deg, var(--upload-a), var(--upload-b));
}

.status-row {
  display: flex;
  align-items: center;
  gap: 12px;
  min-height: 1.5em;
}
.status { margin: 0; color: var(--muted); font-size: 0.95rem; }

.link {
  background: none;
  border: 0;
  padding: 0;
  color: var(--accent);
  cursor: pointer;
  font-size: 0.9rem;
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- Metric cards ---------- */

.metrics {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.metric {
  position: relative;
  padding: 14px 16px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  min-height: 108px;
  container-type: inline-size;
}
.metric h2 {
  margin: 0 0 6px;
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--muted);
}
.metric p { margin: 0; display: flex; align-items: baseline; gap: 6px; position: relative; z-index: 1; }
.metric .value {
  font-size: 1.9rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}
.metric .unit { color: var(--muted); font-size: 0.85rem; }
.metric.is-active { border-color: color-mix(in srgb, var(--accent) 55%, transparent); }

/* Ping / jitter measured during download and upload. Stacked so the layout
   doesn't jump when "—" is replaced by a value; side by side only in cards
   wide enough to fit both values (very large screens). */
.loaded {
  margin: 10px 0 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2px 14px;
  font-size: 0.8rem;
  color: var(--muted);
}
.loaded .loaded-caption {
  grid-column: 1 / -1;
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}
@container (min-width: 250px) {
  .loaded { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
.loaded div { display: flex; align-items: center; gap: 6px; }
.loaded dt::before {
  content: "";
  display: inline-block;
  width: 6px; height: 6px;
  margin-right: 6px;
  border-radius: 50%;
  vertical-align: middle;
}
.loaded-download dt::before { background: var(--download-b); }
.loaded-upload dt::before { background: var(--upload-b); }
.loaded dd {
  margin: 0;
  color: var(--text);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.dot { width: 8px; height: 8px; border-radius: 50%; }
.metric-download .dot { background: var(--download-b); }
.metric-upload .dot { background: var(--upload-b); }
.metric-download.is-active { border-color: color-mix(in srgb, var(--download-b) 55%, transparent); }
.metric-upload.is-active { border-color: color-mix(in srgb, var(--upload-b) 55%, transparent); }

.spark {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  width: 100%;
  height: 44px;
  pointer-events: none;
}

.footer {
  text-align: center;
  font-size: 0.8rem;
  color: var(--muted);
}

/* ---------- Results dialog ---------- */

.results {
  width: min(680px, calc(100vw - 32px));
  padding: 24px;
  border: 1px solid var(--border);
  border-radius: 22px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
}
.results::backdrop {
  background: rgba(5, 8, 14, 0.62);
  backdrop-filter: blur(4px);
}
.results[open] { animation: pop 0.22s ease-out; }
@keyframes pop {
  from { opacity: 0; transform: translateY(10px) scale(0.98); }
  to { opacity: 1; transform: none; }
}
.results h2 { margin: 0 0 16px; font-size: 1.2rem; }
.results-close { position: absolute; top: 12px; right: 12px; margin: 0; }
.results-close button {
  width: 34px; height: 34px;
  border-radius: 50%;
  border: 0;
  background: var(--surface-2);
  font-size: 1.3rem;
  line-height: 1;
  cursor: pointer;
}
.results-image {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 14px;
  border: 1px solid var(--border);
  aspect-ratio: 1200 / 600;
  background: var(--surface-2);
}
.results-actions {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  margin-top: 18px;
}
.results-note { margin: 10px 0 0; min-height: 1.2em; font-size: 0.85rem; color: var(--muted); }

.btn {
  flex: 1 1 auto;
  padding: 11px 18px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--surface-2);
  font-weight: 600;
  cursor: pointer;
  transition: filter 0.15s, transform 0.1s;
}
.btn:hover { filter: brightness(1.1); }
.btn:active { transform: translateY(1px); }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.btn-primary {
  border-color: transparent;
  color: #fff;
  background: linear-gradient(135deg, var(--download-a), var(--upload-a));
}
.btn-ghost { background: transparent; }

/* ---------- Toast ---------- */

.toast {
  position: fixed;
  left: 50%;
  bottom: 24px;
  transform: translateX(-50%);
  max-width: calc(100vw - 32px);
  padding: 10px 16px;
  border-radius: 12px;
  background: var(--surface-2);
  border: 1px solid color-mix(in srgb, var(--danger) 50%, transparent);
  box-shadow: var(--shadow);
  font-size: 0.9rem;
}

/* ---------- Responsive ---------- */

@media (min-width: 1800px) {
  .app { max-width: 1240px; }
}

@media (max-width: 720px) {
  .metrics { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .metric .value { font-size: 1.6rem; }
}

@media (prefers-reduced-motion: reduce) {
  .start { animation: none; }
  .results[open] { animation: none; }
  .progress-bar { transition: none; }
}