:root {
  --bg: #0f0f13;
  --surface: #1a1a24;
  --surface2: #22222e;
  --btn-num: #252533;
  --btn-op: #2e1f4a;
  --btn-equal: #6c47ff;
  --btn-clear: #1f2e3a;
  --accent2: #a78bfa;
  --text: #f0eeff;
  --text-muted: #7a7a99;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background: var(--bg);
  background-image:
    linear-gradient(rgba(108,71,255,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(108,71,255,0.04) 1px, transparent 1px);
  background-size: 40px 40px;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'DM Sans', sans-serif;
  padding: 1rem;
}

.calc-wrapper {
  width: 100%;
  max-width: 360px;
  animation: fadeUp 0.5s ease both;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

.calculator {
  background: var(--surface);
  border-radius: 28px;
  padding: 1.5rem;
  box-shadow: 0 8px 32px rgba(108,71,255,0.18), 0 0 0 1px rgba(255,255,255,0.05);
  position: relative;
  overflow: hidden;
}

.calculator::before {
  content: '';
  position: absolute;
  top: -60px;
  right: -60px;
  width: 200px;
  height: 200px;
  background: radial-gradient(circle, rgba(108,71,255,0.15) 0%, transparent 70%);
  pointer-events: none;
}

.display {
  background: var(--surface2);
  border-radius: 16px;
  padding: 1rem 1.25rem;
  margin-bottom: 1.25rem;
  min-height: 96px;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-end;
  gap: 4px;
  overflow: hidden;
}

.display-expr {
  font-family: 'Space Mono', monospace;
  font-size: 13px;
  color: var(--text-muted);
  min-height: 18px;
  text-align: right;
  word-break: break-all;
}

.display-main {
  font-family: 'Space Mono', monospace;
  font-size: clamp(28px, 8vw, 40px);
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.02em;
  word-break: break-all;
  text-align: right;
  line-height: 1.1;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.btn {
  border: none;
  border-radius: 12px;
  font-size: 18px;
  font-weight: 500;
  cursor: pointer;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.08s, background 0.12s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn:active {
  transform: scale(0.93);
}

.btn-num {
  background: var(--btn-num);
  color: var(--text);
  font-family: 'Space Mono', monospace;
}
.btn-num:hover { background: #2e2e42; }

.btn-op {
  background: var(--btn-op);
  color: var(--accent2);
  font-size: 20px;
  font-family: 'DM Sans', sans-serif;
}
.btn-op:hover { background: #3a2560; }

.btn-clear {
  background: var(--btn-clear);
  color: #7eb8d4;
  font-size: 14px;
  font-family: 'DM Sans', sans-serif;
}
.btn-clear:hover { background: #263642; }

.btn-sign, .btn-percent {
  background: var(--btn-num);
  color: var(--accent2);
  font-family: 'DM Sans', sans-serif;
}
.btn-sign:hover, .btn-percent:hover { background: #2e2e42; }

.btn-equal {
  background: var(--btn-equal);
  color: #fff;
  font-size: 22px;
  box-shadow: 0 4px 20px rgba(108,71,255,0.4);
  font-family: 'DM Sans', sans-serif;
}
.btn-equal:hover {
  background: #7c5aff;
  box-shadow: 0 6px 28px rgba(108,71,255,0.55);
}

.btn-zero {
  grid-column: span 2;
  justify-content: flex-start;
  padding-left: 24px;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}
.blink { animation: blink 0.12s ease; }

@media (max-width: 400px) {
  .calculator { padding: 1rem; }
  .buttons { gap: 8px; }
  .btn { height: 56px; font-size: 16px; }
}

@media (min-width: 600px) {
  .calc-wrapper { max-width: 400px; }
  .btn { height: 72px; font-size: 20px; }
}