:root {
  color-scheme: dark;
  --page-top: #1f2a44;
  --page-bottom: #0c1220;
  --panel-top: rgba(14, 20, 35, 0.94);
  --panel-bottom: rgba(9, 13, 24, 0.98);
  --panel-border: rgba(255, 255, 255, 0.08);
  --display-bg: rgba(255, 255, 255, 0.06);
  --display-text: #f6f8fb;
  --text-muted: #8fa0bc;
  --button-bg: #182133;
  --button-hover: #21304b;
  --button-active: #2a3b5a;
  --button-text: #eef3fb;
  --operator-bg: #ff9f4a;
  --operator-hover: #ffb166;
  --operator-active: #f38b28;
  --operator-text: #1e1407;
  --clear-bg: #7f375f;
  --clear-hover: #99466f;
  --clear-active: #692a4e;
  --equals-bg: #55d1ae;
  --equals-hover: #6ce1bf;
  --equals-active: #36b690;
  --shadow-strong: 0 28px 60px rgba(0, 0, 0, 0.45);
  --shadow-soft: 0 12px 24px rgba(0, 0, 0, 0.25);
}

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

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top, rgba(130, 176, 255, 0.24), transparent 36%),
    linear-gradient(180deg, var(--page-top), var(--page-bottom));
  color: var(--button-text);
  font-family: "Avenir Next", "Trebuchet MS", "Segoe UI", sans-serif;
}

.calculator-page {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 2rem 1rem;
}

.calculator {
  width: min(100%, 25rem);
  padding: 1.5rem;
  border: 1px solid var(--panel-border);
  border-radius: 1.75rem;
  background: linear-gradient(180deg, var(--panel-top), var(--panel-bottom));
  box-shadow: var(--shadow-strong);
  backdrop-filter: blur(18px);
}

.calculator-header {
  margin-bottom: 1.25rem;
}

.calculator-header h1 {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.calculator-display {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  min-height: 6rem;
  margin-bottom: 1.25rem;
  padding: 1.25rem;
  border-radius: 1.25rem;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.08), var(--display-bg));
  color: var(--display-text);
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.05);
  font-family: "IBM Plex Mono", "SFMono-Regular", "Consolas", monospace;
  font-size: clamp(2.4rem, 4vw, 3.6rem);
  font-weight: 500;
  letter-spacing: -0.04em;
  text-align: right;
  overflow-wrap: anywhere;
}

.calculator-display[data-state="error"] {
  color: #ff8f9d;
}

.calculator-keypad {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.75rem;
}

.calculator-button {
  min-height: 4.25rem;
  border: 0;
  border-radius: 1.1rem;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.05), transparent), var(--button-bg);
  color: var(--button-text);
  box-shadow: var(--shadow-soft);
  cursor: pointer;
  font: inherit;
  font-size: 1.35rem;
  font-weight: 700;
  transition:
    transform 140ms ease,
    background-color 140ms ease,
    box-shadow 140ms ease,
    filter 140ms ease;
}

.calculator-button:hover {
  background-color: var(--button-hover);
  transform: translateY(-1px);
}

.calculator-button:active {
  background-color: var(--button-active);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.24);
  transform: translateY(1px) scale(0.98);
}

.calculator-button:focus-visible {
  outline: 3px solid rgba(255, 255, 255, 0.45);
  outline-offset: 2px;
}

.calculator-button-operator {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.18), transparent),
    var(--operator-bg);
  color: var(--operator-text);
}

.calculator-button-operator:hover {
  background-color: var(--operator-hover);
}

.calculator-button-operator:active {
  background-color: var(--operator-active);
}

.calculator-button-clear {
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), transparent),
    var(--clear-bg);
}

.calculator-button-clear:hover {
  background-color: var(--clear-hover);
}

.calculator-button-clear:active {
  background-color: var(--clear-active);
}

.calculator-button-equals {
  grid-row: span 2;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.12), transparent),
    var(--equals-bg);
  color: #072019;
}

.calculator-button-equals:hover {
  background-color: var(--equals-hover);
}

.calculator-button-equals:active {
  background-color: var(--equals-active);
}

.calculator-button-zero {
  grid-column: span 2;
}

@media (max-width: 480px) {
  .calculator-page {
    padding: 1rem 0.75rem;
  }

  .calculator {
    padding: 1rem;
    border-radius: 1.5rem;
  }

  .calculator-display {
    min-height: 5.2rem;
    padding: 1rem;
    font-size: clamp(2rem, 12vw, 3rem);
  }

  .calculator-keypad {
    gap: 0.6rem;
  }

  .calculator-button {
    min-height: 3.8rem;
    border-radius: 0.95rem;
    font-size: 1.2rem;
  }
}