:root {
  --bg: #0d0d0d;
  --fg: #fff;
  --digit-xl: clamp(56px, 11vw, 140px);
  --digit-sm: clamp(28px, 5vw, 48px);
  --digit-key: clamp(34px, 5.5vw, 56px);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--fg);
  font-family: "Helvetica Neue", Arial, sans-serif;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* ---------- Every button: just the symbol, no box ---------- */
button {
  background: none;
  border: none;
  padding: 0;
  margin: 0;
  color: var(--fg);
  font: inherit;
  cursor: pointer;
  outline: none;
  -webkit-tap-highlight-color: transparent;
  transition: opacity 0.15s, transform 0.1s;
}
button:hover { opacity: 0.6; }
button:active { transform: scale(0.88); }

/* ---------- Tabs ---------- */
.tabs {
  display: flex;
  justify-content: center;
  gap: clamp(28px, 6vw, 64px);
  padding: 24px 0 8px;
}
.tab {
  font-size: clamp(32px, 5vw, 48px);
  opacity: 0.35;
}
.tab:hover { opacity: 0.7; }
.tab.active { opacity: 1; }

/* ---------- Pages ---------- */
main {
  flex: 1;
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}
.page {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: clamp(16px, 3vh, 32px);
  width: 100%;
  padding: 16px;
  text-align: center;
}
.page.active { display: flex; }

/* ---------- Number display ---------- */
.tokens {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 4px;
  max-width: 96vw;
}
.tokens.result { --size: var(--digit-xl); min-height: var(--digit-xl); }
.tokens.small  { --size: var(--digit-sm); min-height: var(--digit-sm); }
.expr { opacity: 0.7; }

.tok {
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.tok.digit { width: var(--size); height: var(--size); }
.tok.digit video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  pointer-events: none;
}
.tok .fb { font-size: calc(var(--size) * 0.7); font-weight: 200; line-height: 1; }
.tok.sym { font-size: calc(var(--size) * 0.7); font-weight: 200; min-width: calc(var(--size) * 0.45); }

/* ---------- Controls ---------- */
.controls {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: clamp(24px, 5vw, 56px);
}
.sym-btn { font-size: clamp(34px, 5vw, 52px); line-height: 1; }
.mode-label { font-size: clamp(18px, 2.5vw, 26px); font-weight: 200; letter-spacing: 0.05em; }

/* ---------- Keypads ---------- */
.ops {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: clamp(18px, 3.5vw, 40px);
}
.ops .sym-btn { font-size: clamp(30px, 4.5vw, 46px); }

.keypad {
  display: grid;
  grid-template-columns: repeat(13, var(--digit-key));
  gap: 6px;
  justify-content: center;
}
.keypad.numerals { grid-template-columns: repeat(5, var(--digit-key)); }
.keypad .key {
  width: var(--digit-key);
  height: var(--digit-key);
  display: flex;
  align-items: center;
  justify-content: center;
}
.keypad .key .tokens { --size: var(--digit-key); }
.keypad.numerals .key { font-size: calc(var(--digit-key) * 0.7); font-weight: 200; }

@media (max-width: 760px) {
  .keypad { grid-template-columns: repeat(7, var(--digit-key)); }
}

#conv-swap {
  rotate: 90deg;
}
#focus-toggle {
  position: fixed;
  top: 20px;
  right: 24px;
  font-size: clamp(28px, 4vw, 40px);
  opacity: 0.35;
  z-index: 10;
}
#focus-toggle:hover { opacity: 1; }

body.focus .tabs,
body.focus .controls,
body.focus .ops,
body.focus .keypad,
body.focus .expr {
  display: none;
}