:root {
  color-scheme: light;
  font-family:
    ui-rounded, "SF Pro Rounded", "Avenir Next", system-ui, -apple-system,
    BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-synthesis: none;
  --ink: #15253d;
  --muted: #64748b;
  --surface: #ffffff;
  --line: #cbd5e1;
  --blue: #2563eb;
  --red: #dc4c64;
  --green: #0f9f75;
  --focus: #7c3aed;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-height: 100%;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 8% 5%, rgb(37 99 235 / 8%), transparent 28rem),
    #f4f7fb;
  overscroll-behavior: none;
}

button,
svg {
  -webkit-tap-highlight-color: transparent;
}

.app-shell {
  width: min(100%, 1220px);
  margin: 0 auto;
  padding:
    max(20px, env(safe-area-inset-top))
    max(20px, env(safe-area-inset-right))
    max(20px, env(safe-area-inset-bottom))
    max(20px, env(safe-area-inset-left));
}

.app-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 18px;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--blue);
  font-size: clamp(0.85rem, 1.7vw, 1rem);
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(1.7rem, 4.2vw, 3.35rem);
  line-height: 1.02;
  letter-spacing: -0.035em;
}

.subtitle {
  margin: 6px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 2vw, 1.35rem);
  font-weight: 650;
}

.local-note {
  flex: 0 0 auto;
  margin: 4px 0 0;
  padding: 9px 14px;
  border: 1px solid #b9e5d5;
  border-radius: 999px;
  color: #087154;
  background: #ecfdf5;
  font-size: clamp(0.75rem, 1.4vw, 0.92rem);
  font-weight: 750;
  white-space: nowrap;
}

.local-note span {
  margin-right: 5px;
  font-size: 0.7em;
}

.visualizer {
  padding: clamp(12px, 2vw, 20px);
  border: 1px solid rgb(203 213 225 / 80%);
  border-radius: 28px;
  background: rgb(255 255 255 / 92%);
  box-shadow: 0 22px 70px rgb(30 41 59 / 10%);
}

#triangle-board {
  display: block;
  width: 100%;
  height: clamp(390px, 57dvh, 680px);
  border-radius: 22px;
  touch-action: none;
  user-select: none;
}

.board-background {
  fill: #f8fafc;
  stroke: #dbe4ef;
  stroke-width: 4;
}

.triangle-shape {
  fill: rgb(37 99 235 / 5%);
  stroke: var(--ink);
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 8;
}

.angle-sector {
  opacity: 0.14;
}

.angle-arc {
  fill: none;
  stroke-linecap: round;
  stroke-width: 12;
}

.angle-label {
  paint-order: stroke;
  stroke: #f8fafc;
  stroke-linejoin: round;
  stroke-width: 12px;
  font-size: 42px;
  font-weight: 850;
  text-anchor: middle;
  dominant-baseline: middle;
}

.drag-hit {
  cursor: grab;
  fill: transparent;
  pointer-events: all;
}

.drag-hit:active {
  cursor: grabbing;
}

.drag-hit:focus-visible {
  fill: rgb(124 58 237 / 10%);
  stroke: var(--focus);
  stroke-width: 5;
}

.vertex-dot {
  pointer-events: none;
  stroke: white;
  stroke-width: 7;
  filter: drop-shadow(0 5px 7px rgb(15 23 42 / 25%));
}

.vertex-a {
  fill: var(--blue);
}

.vertex-b {
  fill: var(--red);
}

.vertex-c {
  fill: var(--green);
}

.result-panel {
  margin: clamp(8px, 1.3vw, 14px) 0;
  padding: clamp(10px, 1.4vw, 16px);
  border-radius: 20px;
  color: white;
  background: var(--ink);
  text-align: center;
}

.result-label {
  margin: 0 0 2px;
  color: #cbd5e1;
  font-size: clamp(0.8rem, 1.6vw, 1rem);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.angle-equation {
  margin: 0;
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.75rem, 5vw, 4.15rem);
  font-weight: 900;
  letter-spacing: 0.01em;
  line-height: 1.12;
}

.angle-equation .term-a {
  color: #72a3ff;
}

.angle-equation .term-b {
  color: #ff8fa3;
}

.angle-equation .term-c {
  color: #65d6b3;
}

.angle-equation .total {
  color: white;
}

.controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.interaction-hint {
  min-height: 1.5em;
  margin: 0;
  color: var(--muted);
  font-size: clamp(0.95rem, 1.8vw, 1.15rem);
  font-weight: 650;
}

.interaction-hint.is-blocked {
  color: #a6384d;
}

.reset-button {
  min-height: 52px;
  padding: 0 20px;
  border: 2px solid #cbd5e1;
  border-radius: 14px;
  color: var(--ink);
  background: white;
  font: inherit;
  font-size: 1rem;
  font-weight: 800;
  white-space: nowrap;
  cursor: pointer;
}

.reset-button:hover {
  border-color: #94a3b8;
  background: #f8fafc;
}

.reset-button:focus-visible {
  outline: 4px solid rgb(124 58 237 / 30%);
  outline-offset: 3px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

noscript {
  display: block;
  margin-top: 12px;
  color: #a6384d;
  font-weight: 700;
}

@media (max-width: 700px) {
  .app-shell {
    padding-inline: 12px;
  }

  .app-header {
    display: block;
  }

  .local-note {
    display: inline-block;
    margin-top: 10px;
  }

  #triangle-board {
    height: clamp(390px, 56dvh, 570px);
  }

  .controls {
    align-items: stretch;
    flex-direction: column;
  }

  .reset-button {
    width: 100%;
  }
}

@media (orientation: landscape) and (max-height: 820px) {
  .app-shell {
    padding-block: 12px;
  }

  .app-header {
    margin-bottom: 10px;
  }

  .subtitle {
    display: inline;
    margin-left: 8px;
  }

  .visualizer {
    padding-block: 10px;
  }

  #triangle-board {
    height: clamp(330px, 52dvh, 470px);
  }

  .result-panel {
    padding-block: 8px;
  }
}

@media (prefers-reduced-motion: no-preference) {
  .reset-button,
  .drag-hit {
    transition:
      background-color 140ms ease,
      border-color 140ms ease,
      fill 140ms ease;
  }
}