:root {
  --bg-top: #0f1822;
  --bg-bottom: #1f3343;
  --panel: rgba(11, 18, 27, 0.74);
  --panel-strong: rgba(7, 13, 21, 0.88);
  --panel-soft: rgba(240, 245, 248, 0.08);
  --line: rgba(188, 209, 222, 0.16);
  --line-strong: rgba(188, 209, 222, 0.28);
  --text-main: #eef4ef;
  --text-muted: #afbec8;
  --text-soft: #7e939f;
  --accent-cyan: #6ef0dc;
  --accent-gold: #ffd184;
  --accent-coral: #ff8f6b;
  --accent-blue: #7db4ff;
  --shadow: 0 28px 70px rgba(2, 7, 14, 0.4);
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 16px;
  --radius-sm: 12px;
  --ease: 180ms ease;
}

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

html {
  font-size: 16px;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Trebuchet MS", "Gill Sans", sans-serif;
  color: var(--text-main);
  background:
    radial-gradient(circle at 20% 20%, rgba(110, 240, 220, 0.14), transparent 28%),
    radial-gradient(circle at 85% 12%, rgba(255, 209, 132, 0.12), transparent 30%),
    radial-gradient(circle at 72% 78%, rgba(125, 180, 255, 0.14), transparent 34%),
    linear-gradient(155deg, var(--bg-top), var(--bg-bottom));
}

button,
input {
  font: inherit;
}

.page-shell {
  position: relative;
  min-height: 100vh;
  overflow: hidden;
  padding: 2rem;
}

.ambient {
  position: absolute;
  border-radius: 999px;
  filter: blur(10px);
  opacity: 0.75;
  pointer-events: none;
}

.ambient-one {
  width: 22rem;
  height: 22rem;
  top: 6%;
  left: -6%;
  background: radial-gradient(circle, rgba(255, 209, 132, 0.28), transparent 70%);
  animation: drift 12s ease-in-out infinite;
}

.ambient-two {
  width: 28rem;
  height: 28rem;
  right: -10%;
  bottom: -10%;
  background: radial-gradient(circle, rgba(110, 240, 220, 0.18), transparent 68%);
  animation: drift 15s ease-in-out infinite reverse;
}

.calculator {
  position: relative;
  z-index: 1;
  width: min(1200px, 100%);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(360px, 0.92fr);
  gap: 1.25rem;
  align-items: start;
}

.display-panel,
.controls-panel {
  backdrop-filter: blur(18px);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.05), rgba(255, 255, 255, 0.02)),
    var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
}

.display-panel {
  padding: 1.5rem;
  display: grid;
  gap: 1rem;
}

.controls-panel {
  padding: 1.35rem;
  display: grid;
  gap: 1rem;
}

.panel-top,
.section-heading,
.preview-row,
.meta-row,
.mode-cluster,
.memory-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.panel-top {
  align-items: start;
}

.eyebrow {
  margin: 0 0 0.4rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  font-size: 0.72rem;
  color: var(--accent-gold);
}

h1,
h2 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 600;
}

h1 {
  font-size: clamp(2rem, 4vw, 2.75rem);
  line-height: 1;
}

h2 {
  font-size: 1.05rem;
}

.section-heading {
  align-items: end;
}

.section-heading p {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.92rem;
}

.mode-cluster {
  flex-wrap: wrap;
  justify-content: flex-end;
}

.mode-pill,
.toolbar-button {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-main);
  padding: 0.72rem 1rem;
  border-radius: 999px;
  cursor: pointer;
  transition:
    transform var(--ease),
    border-color var(--ease),
    background var(--ease),
    color var(--ease);
}

.mode-pill:hover,
.toolbar-button:hover,
.mode-pill:focus-visible,
.toolbar-button:focus-visible,
.key:hover,
.key:focus-visible {
  transform: translateY(-1px);
  border-color: var(--line-strong);
}

.mode-pill.is-active {
  background: linear-gradient(135deg, rgba(110, 240, 220, 0.18), rgba(255, 209, 132, 0.18));
  color: var(--accent-cyan);
}

.display-card,
.history-panel,
.insight-card {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.04), rgba(255, 255, 255, 0.02)),
    var(--panel-strong);
}

.display-card {
  padding: 1.2rem;
  display: grid;
  gap: 1rem;
}

.input-label {
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-soft);
}

.expression-input {
  width: 100%;
  border: 1px solid rgba(188, 209, 222, 0.22);
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-main);
  padding: 1rem 1.1rem;
  font-family: "Lucida Console", "Courier New", monospace;
  font-size: clamp(1rem, 2vw, 1.2rem);
  outline: none;
  transition: border-color var(--ease), background var(--ease), box-shadow var(--ease);
}

.expression-input::placeholder {
  color: rgba(175, 190, 200, 0.65);
}

.expression-input:focus {
  border-color: rgba(110, 240, 220, 0.48);
  background: rgba(255, 255, 255, 0.05);
  box-shadow: 0 0 0 4px rgba(110, 240, 220, 0.08);
}

.preview-row {
  align-items: center;
}

.result-badge {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 6rem;
  padding: 0.45rem 0.8rem;
  border-radius: 999px;
  font-size: 0.76rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent-gold);
  background: rgba(255, 209, 132, 0.1);
  border: 1px solid rgba(255, 209, 132, 0.2);
}

.result-badge.is-exact {
  color: var(--accent-cyan);
  background: rgba(110, 240, 220, 0.1);
  border-color: rgba(110, 240, 220, 0.24);
}

.result-badge.is-error {
  color: var(--accent-coral);
  background: rgba(255, 143, 107, 0.1);
  border-color: rgba(255, 143, 107, 0.22);
}

.result-output {
  flex: 1;
  min-width: 0;
  font-family: "Lucida Console", "Courier New", monospace;
  font-size: clamp(1.9rem, 5vw, 3.25rem);
  line-height: 1.05;
  text-align: right;
  overflow-wrap: anywhere;
}

.meta-row {
  align-items: start;
}

.status-line,
.memory-line {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.92rem;
  line-height: 1.45;
}

.memory-line {
  text-align: right;
}

.memory-toolbar {
  flex-wrap: wrap;
  justify-content: flex-start;
}

.toolbar-button {
  padding: 0.72rem 0.95rem;
}

.insight-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.85rem;
}

.insight-card {
  padding: 1rem;
}

.insight-card h2 {
  margin-bottom: 0.45rem;
}

.insight-card p {
  margin: 0;
  color: var(--text-muted);
  line-height: 1.5;
}

.history-panel {
  padding: 1rem;
  display: grid;
  gap: 0.8rem;
}

.history-list {
  display: grid;
  gap: 0.65rem;
  max-height: 21rem;
  overflow: auto;
  padding-right: 0.15rem;
}

.history-list::-webkit-scrollbar {
  width: 9px;
}

.history-list::-webkit-scrollbar-thumb {
  border-radius: 999px;
  background: rgba(175, 190, 200, 0.18);
}

.history-empty {
  padding: 1.05rem;
  border-radius: var(--radius-md);
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-soft);
  text-align: center;
}

.history-item {
  width: 100%;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 0.9rem 1rem;
  color: inherit;
  background: rgba(255, 255, 255, 0.035);
  cursor: pointer;
  transition:
    transform var(--ease),
    border-color var(--ease),
    background var(--ease);
}

.history-item:hover,
.history-item:focus-visible {
  transform: translateY(-1px);
  border-color: rgba(110, 240, 220, 0.22);
  background: rgba(255, 255, 255, 0.055);
}

.history-expression,
.history-result {
  display: block;
  font-family: "Lucida Console", "Courier New", monospace;
}

.history-expression {
  color: var(--text-muted);
  margin-bottom: 0.35rem;
  font-size: 0.88rem;
}

.history-result {
  font-size: 1rem;
}

.history-tag {
  display: inline-block;
  margin-top: 0.45rem;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-soft);
}

.keypad {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 0.75rem;
}

.key {
  min-height: 4.25rem;
  border-radius: var(--radius-md);
  border: 1px solid rgba(188, 209, 222, 0.16);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.11), rgba(255, 255, 255, 0.03)),
    rgba(5, 12, 20, 0.88);
  color: var(--text-main);
  cursor: pointer;
  font-size: 1.05rem;
  font-weight: 600;
  transition:
    transform var(--ease),
    border-color var(--ease),
    box-shadow var(--ease),
    background var(--ease);
}

.key:focus-visible,
.mode-pill:focus-visible,
.toolbar-button:focus-visible,
.history-item:focus-visible,
.expression-input:focus-visible {
  outline: none;
}

.key:hover,
.key:focus-visible {
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.08), 0 8px 24px rgba(2, 7, 14, 0.18);
}

.key-function {
  color: var(--accent-gold);
  background:
    linear-gradient(180deg, rgba(255, 209, 132, 0.12), rgba(255, 255, 255, 0.03)),
    rgba(5, 12, 20, 0.9);
}

.key-utility {
  color: var(--accent-blue);
}

.key-operator {
  color: var(--accent-cyan);
  background:
    linear-gradient(180deg, rgba(110, 240, 220, 0.14), rgba(255, 255, 255, 0.03)),
    rgba(5, 12, 20, 0.9);
}

.key-answer {
  grid-column: span 2;
  color: #09111a;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-gold));
  border-color: transparent;
  box-shadow: 0 16px 40px rgba(110, 240, 220, 0.18);
}

.key-zero {
  grid-column: span 2;
}

kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.7rem;
  padding: 0.14rem 0.4rem;
  border-radius: 8px;
  border: 1px solid rgba(188, 209, 222, 0.22);
  background: rgba(255, 255, 255, 0.06);
  font-family: "Lucida Console", "Courier New", monospace;
  font-size: 0.82rem;
}

@keyframes drift {
  0%,
  100% {
    transform: translate3d(0, 0, 0) scale(1);
  }
  50% {
    transform: translate3d(0, 14px, 0) scale(1.03);
  }
}

@media (max-width: 1080px) {
  .calculator {
    grid-template-columns: 1fr;
  }

  .controls-panel {
    order: 2;
  }
}

@media (max-width: 760px) {
  .page-shell {
    padding: 1rem;
  }

  .display-panel,
  .controls-panel {
    padding: 1rem;
    border-radius: 24px;
  }

  .panel-top,
  .meta-row,
  .section-heading {
    flex-direction: column;
    align-items: flex-start;
  }

  .preview-row {
    align-items: flex-start;
    flex-direction: column;
  }

  .memory-line {
    text-align: left;
  }

  .insight-grid {
    grid-template-columns: 1fr;
  }

  .keypad {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .key-answer,
  .key-zero {
    grid-column: span 2;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition-duration: 1ms !important;
    scroll-behavior: auto !important;
  }
}

@media (max-width: 480px) {
  .keypad {
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
  }

  .key {
    min-height: 3rem;
    font-size: 0.9rem;
  }

  .display-panel,
  .controls-panel {
    padding: 0.8rem;
  }

  .result-output {
    font-size: clamp(1.5rem, 6vw, 2.5rem);
  }

  .page-shell {
    padding: 0.5rem;
  }
}