/* ===================================================
   Design tokens — Aurora theme (teal -> violet -> magenta)
   =================================================== */
:root {
  --teal-950: #04211f;
  --teal-800: #0a3d38;
  --violet-800: #3b1568;
  --magenta-600: #9d2a8c;
  --accent-gold: #f5c451;
  --accent-mint: #5eead4;
  --accent-mint-soft: rgba(94, 234, 212, 0.14);
  --text-primary: #f4fbf9;
  --text-muted: #9fc9c1;
  --glass-fill: rgba(9, 34, 33, 0.5);
  --glass-border: rgba(148, 226, 213, 0.16);
  --key-fill: rgba(255, 255, 255, 0.045);
  --key-border: rgba(255, 255, 255, 0.09);
  --font-display: 'IBM Plex Mono', monospace;
  --font-body: 'Sora', sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--text-primary);
}

/* ===================================================
   Hero: aurora teal-to-magenta gradient
   =================================================== */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2.25rem;
  padding: 3rem 1.5rem;
  background:
    radial-gradient(circle at 12% 15%, rgba(94, 234, 212, 0.16), transparent 45%),
    radial-gradient(circle at 88% 20%, rgba(157, 42, 140, 0.35), transparent 50%),
    radial-gradient(circle at 50% 100%, rgba(59, 21, 104, 0.55), transparent 60%),
    linear-gradient(150deg, var(--teal-950) 0%, var(--teal-800) 40%, var(--violet-800) 78%, var(--magenta-600) 115%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  /* soft aurora "veil" streaks for atmosphere */
  content: "";
  position: absolute;
  inset: -10%;
  background:
    linear-gradient(115deg, transparent 30%, rgba(94, 234, 212, 0.07) 45%, transparent 60%),
    linear-gradient(115deg, transparent 55%, rgba(245, 196, 81, 0.06) 68%, transparent 82%);
  pointer-events: none;
  animation: drift 18s ease-in-out infinite alternate;
}

@keyframes drift {
  from { transform: translateX(-2%) translateY(-1%); }
  to   { transform: translateX(2%) translateY(1%); }
}

.hero__header {
  text-align: center;
  max-width: 40rem;
  position: relative;
  z-index: 1;
}

.hero__eyebrow {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 0.72rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent-mint);
  background: var(--accent-mint-soft);
  border: 1px solid rgba(94, 234, 212, 0.3);
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  margin-bottom: 1.1rem;
}

.hero__title {
  font-family: var(--font-body);
  font-weight: 800;
  font-size: clamp(2.6rem, 7vw, 4rem);
  margin: 0 0 0.6rem;
  letter-spacing: -0.03em;
}

.hero__dot { color: var(--accent-gold); }

.hero__subtitle {
  color: var(--text-muted);
  font-size: 1.02rem;
  line-height: 1.55;
  margin: 0;
}

.hero__footer {
  color: var(--text-muted);
  font-size: 0.8rem;
  letter-spacing: 0.02em;
  position: relative;
  z-index: 1;
}

/* ===================================================
   Calculator card
   =================================================== */
.calculator {
  position: relative;
  z-index: 1;
  width: min(360px, 92vw);
  background: var(--glass-fill);
  border: 1px solid var(--glass-border);
  border-radius: 28px;
  padding: 1.5rem 1.35rem 1.25rem;
  backdrop-filter: blur(18px);
  box-shadow:
    0 30px 60px -20px rgba(0, 0, 0, 0.6),
    0 0 0 1px rgba(255, 255, 255, 0.02) inset;
}

.calculator__display {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: flex-end;
  gap: 0.35rem;
  min-height: 6.4rem;
  padding: 0.9rem 1.1rem 1.1rem;
  margin-bottom: 1.1rem;
  border-radius: 18px;
  background: rgba(3, 15, 14, 0.55);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.calculator__expression {
  font-family: var(--font-display);
  font-size: 0.95rem;
  color: var(--text-muted);
  min-height: 1.2rem;
  word-break: break-all;
  text-align: right;
}

.calculator__result {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.8rem, 8vw, 2.4rem);
  line-height: 1.1;
  word-break: break-all;
  text-align: right;
  transition: color 0.15s ease;
}

.calculator__result.is-error {
  color: #ff8a8a;
  font-size: 1.35rem;
}

.calculator__keypad {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
}

.key {
  font-family: var(--font-display);
  font-size: 1.05rem;
  color: var(--text-primary);
  background: var(--key-fill);
  border: 1px solid var(--key-border);
  border-radius: 14px;
  padding: 0.9rem 0;
  cursor: pointer;
  transition: transform 0.08s ease, background 0.15s ease, border-color 0.15s ease;
  -webkit-tap-highlight-color: transparent;
}

.key:hover { background: rgba(255, 255, 255, 0.09); }
.key:active { transform: scale(0.94); }

.key:focus-visible {
  outline: 2px solid var(--accent-mint);
  outline-offset: 2px;
}

.key--util {
  color: var(--accent-mint);
  background: rgba(94, 234, 212, 0.08);
  border-color: rgba(94, 234, 212, 0.22);
}

.key--operator {
  color: var(--accent-gold);
  font-weight: 700;
  background: rgba(245, 196, 81, 0.06);
  border-color: rgba(245, 196, 81, 0.18);
}

.key--equals {
  grid-column: span 2;
  background: linear-gradient(135deg, var(--accent-mint), var(--magenta-600));
  color: #04211f;
  font-weight: 700;
  border: none;
}

.key--equals:hover { filter: brightness(1.08); }

.key--zero { grid-column: span 1; }

.key.is-flash {
  background: rgba(245, 196, 81, 0.3) !important;
}

.calculator__hint {
  margin: 1.1rem 0 0;
  text-align: center;
  font-size: 0.72rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.calculator__hint kbd {
  font-family: var(--font-display);
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 4px;
  padding: 0.05rem 0.3rem;
  font-size: 0.68rem;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .key { transition: none; }
  .hero::before { animation: none; }
}

/* Small screens */
@media (max-width: 380px) {
  .hero { padding: 2rem 1rem; }
  .calculator { padding: 1.25rem 1rem 1rem; }
}