:root {
  color-scheme: dark;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Yu Gothic UI", sans-serif;
  --bg: #0c0f15;
  --panel: #161b24;
  --panel-2: #202735;
  --text: #f5f7fb;
  --muted: #aab4c5;
  --line: #303949;
  --accent: #64e6c3;
  --accent-2: #78b7ff;
  --danger: #ff6b7a;
  --shadow: 0 14px 42px rgba(0, 0, 0, 0.28);
}

* { box-sizing: border-box; }
html { background: var(--bg); }
body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 20% -10%, rgba(100, 230, 195, 0.13), transparent 34rem),
    var(--bg);
  color: var(--text);
  padding-bottom: env(safe-area-inset-bottom);
}
button, input, label { font: inherit; }
button, .button-like, .file-button {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--panel-2);
  color: var(--text);
  padding: 0.68rem 0.86rem;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
button:disabled { opacity: 0.42; cursor: not-allowed; }
button:active:not(:disabled), .button-like:active, .file-button:active { transform: translateY(1px); }
input[type="file"] { display: none; }
input[type="range"] { width: 100%; accent-color: var(--accent); }
input[type="checkbox"] { width: 1.2rem; height: 1.2rem; accent-color: var(--accent); }

.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: calc(0.8rem + env(safe-area-inset-top)) max(1rem, env(safe-area-inset-right)) 0.8rem max(1rem, env(safe-area-inset-left));
  border-bottom: 1px solid rgba(255,255,255,.07);
  background: rgba(12, 15, 21, 0.86);
  backdrop-filter: blur(14px);
  position: sticky;
  top: 0;
  z-index: 20;
}
.app-header h1 { font-size: 1.14rem; margin: 0; letter-spacing: .02em; }
.app-header p { color: var(--muted); font-size: .76rem; margin: .18rem 0 0; }
.badge {
  display: inline-flex;
  align-items: center;
  border: 1px solid rgba(100, 230, 195, .35);
  color: var(--accent);
  background: rgba(100, 230, 195, .08);
  border-radius: 999px;
  padding: .35rem .55rem;
  font-size: .72rem;
  white-space: nowrap;
}
.badge.subtle { color: var(--muted); border-color: var(--line); background: transparent; }

.layout {
  width: min(1400px, 100%);
  margin: 0 auto;
  padding: 1rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 360px);
  gap: 1rem;
}
.card {
  background: linear-gradient(180deg, rgba(255,255,255,.025), transparent 8rem), var(--panel);
  border: 1px solid var(--line);
  border-radius: 18px;
  box-shadow: var(--shadow);
}
.workspace { padding: .9rem; align-self: start; }
.controls { display: grid; gap: .8rem; align-content: start; }
.panel { padding: .9rem; }
.panel h2 { font-size: .95rem; margin: 0 0 .8rem; }
.panel label { display: block; color: var(--muted); font-size: .84rem; margin: .75rem 0; }
.panel output { float: right; color: var(--text); font-variant-numeric: tabular-nums; }
.switch-row { display: flex !important; align-items: center; gap: .65rem; }
.switch-row span { color: var(--text); }
.hint { color: var(--muted); font-size: .76rem; line-height: 1.55; margin: .55rem 0 0; }

.file-row, .quick-actions { display: flex; flex-wrap: wrap; gap: .55rem; }
.file-row { margin-bottom: .7rem; }
.primary-button, .accent-button { border-color: rgba(100,230,195,.48); background: rgba(100,230,195,.12); }
.danger-button { border-color: rgba(255,107,122,.36); color: #ffdce0; }
.file-button { display: inline-flex; align-items: center; justify-content: center; }

.tool-strip {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: .35rem;
  margin-bottom: .65rem;
}
.tool { min-height: 40px; padding: .5rem .25rem; font-size: .78rem; }
.tool.active { outline: 2px solid var(--accent); outline-offset: -2px; background: rgba(100,230,195,.12); }
.status {
  min-height: 1.5rem;
  color: var(--muted);
  font-size: .78rem;
  padding: 0 .1rem .45rem;
}

.canvas-shell {
  position: relative;
  width: 100%;
  min-height: 360px;
  border-radius: 14px;
  overflow: hidden;
  background:
    linear-gradient(45deg, rgba(255,255,255,.035) 25%, transparent 25%, transparent 75%, rgba(255,255,255,.035) 75%),
    linear-gradient(45deg, rgba(255,255,255,.035) 25%, transparent 25%, transparent 75%, rgba(255,255,255,.035) 75%),
    #090b0f;
  background-size: 24px 24px;
  background-position: 0 0, 12px 12px;
  border: 1px solid var(--line);
}
#boardCanvas {
  display: block;
  width: 100%;
  height: auto;
  max-height: 78vh;
  object-fit: contain;
  margin: 0 auto;
  touch-action: none;
  user-select: none;
  -webkit-user-select: none;
}
.empty-state {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  text-align: center;
  gap: .35rem;
  color: var(--muted);
  pointer-events: none;
}
.empty-state strong { color: var(--text); }
.quick-actions { margin-top: .7rem; }
.quick-actions button { flex: 1 1 130px; }

.selection-title-row { display: flex; align-items: center; justify-content: space-between; gap: .5rem; }
.button-grid { display: grid; grid-template-columns: 1fr 1fr; gap: .5rem; }
.button-like { display: flex; align-items: center; justify-content: center; text-align: center; }
.help summary { cursor: pointer; font-weight: 700; }
.help ol { color: var(--muted); padding-left: 1.25rem; line-height: 1.65; font-size: .82rem; }
.help p { color: var(--muted); line-height: 1.6; font-size: .78rem; }
footer { color: var(--muted); font-size: .7rem; text-align: center; padding: 0 1rem 1.5rem; }

@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; padding: .65rem; }
  .workspace { padding: .65rem; }
  .controls { grid-template-columns: 1fr; }
  .app-header { position: relative; }
  #boardCanvas { max-height: none; }
}

@media (max-width: 520px) {
  .app-header p { display: none; }
  .tool-strip { grid-template-columns: repeat(3, 1fr); }
  .file-row button, .file-row label { flex: 1 1 30%; font-size: .78rem; }
  .button-grid { grid-template-columns: 1fr; }
  .panel { box-shadow: none; }
}