/* ==========================================================================
   KRAFTWERK SC-70 // SWISS MINIMALIST + BENTO + TYPEWRITER SCIENTIFIC ENGINE
   ========================================================================== */

:root {
  /* Swiss Neutral Canvas (Light Theme default) */
  --bg-canvas: #EDECE6;
  --bg-card: #F9F9F6;
  --bg-screen: #E2E1D8;
  --text-primary: #121316;
  --text-secondary: #62646B;
  --text-tertiary: #92959E;
  --border-hairline: rgba(18, 19, 22, 0.12);
  --border-strong: rgba(18, 19, 22, 0.28);
  
  /* Swiss Iconic Accents */
  --swiss-red: #E6392E;
  --swiss-red-hover: #D02B20;
  --swiss-red-active: #B52218;
  --amber-warn: #D97706;
  --accent-blue: #0052FF;
  
  /* Typewriter Keycap Aesthetics (Light Mode) */
  --key-num-rim-top: #FFFFFF;
  --key-num-rim-bot: #D5D5CE;
  --key-num-dish-top: #FFFFFF;
  --key-num-dish-bot: #F4F4F0;
  --key-num-text: #121316;
  --key-num-shadow: #B8B8AE;
  
  --key-fn-rim-top: #FFFFFF;
  --key-fn-rim-bot: #CECDC3;
  --key-fn-dish-top: #FAFAF8;
  --key-fn-dish-bot: #E7E6DE;
  --key-fn-text: #2C2D33;
  --key-fn-shadow: #B2B1A5;
  
  --key-op-rim-top: #4A4C56;
  --key-op-rim-bot: #36373F;
  --key-op-dish-top: #383A44;
  --key-op-dish-bot: #222328;
  --key-op-text: #FFFFFF;
  --key-op-shadow: #121316;

  --card-radius: 18px;
  --key-radius: 50%;
  
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-display: 'Space Grotesk', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --font-typewriter: 'Courier Prime', monospace;
  
  --shadow-bento: 0 10px 30px -5px rgba(0, 0, 0, 0.05), 0 0 0 1px var(--border-hairline);
  --transition-fast: all 0.12s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ==========================================================================
   DARK THEME (HIGH CONTRAST & VISIBLE KEYS)
   ========================================================================== */
body.theme-dark {
  --bg-canvas: #0C0D10;
  --bg-card: #15171D;
  --bg-screen: #0A0B0E;
  --text-primary: #FFFFFF;
  --text-secondary: #A6ACBA;
  --text-tertiary: #676E80;
  --border-hairline: rgba(255, 255, 255, 0.1);
  --border-strong: rgba(255, 255, 255, 0.25);
  
  /* Number Keys in Dark Mode: Gunmetal Bezel + Obsidian Dish + Crisp White Digits */
  --key-num-rim-top: #424756;
  --key-num-rim-bot: #282C37;
  --key-num-dish-top: #2B303C;
  --key-num-dish-bot: #1B1E26;
  --key-num-text: #FFFFFF;
  --key-num-shadow: #0A0B0E;
  
  /* Scientific Keys in Dark Mode: Graphite Dish + Bright Silver Text */
  --key-fn-rim-top: #363B48;
  --key-fn-rim-bot: #20242D;
  --key-fn-dish-top: #232732;
  --key-fn-dish-bot: #161820;
  --key-fn-text: #D8DCE8;
  --key-fn-shadow: #0A0B0E;
  
  /* Operators in Dark Mode: Crisp Dark Cobalt / Charcoal + Red/White Accents */
  --key-op-rim-top: #4E5568;
  --key-op-rim-bot: #333847;
  --key-op-dish-top: #383E4E;
  --key-op-dish-bot: #252934;
  --key-op-text: #FFFFFF;
  --key-op-shadow: #0A0B0E;

  --shadow-bento: 0 14px 40px -8px rgba(0, 0, 0, 0.6), 0 0 0 1px var(--border-hairline);
}

/* Base Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-font-smoothing: antialiased;
}

body {
  background-color: var(--bg-canvas);
  color: var(--text-primary);
  font-family: var(--font-sans);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 24px 16px;
  position: relative;
  overflow-x: hidden;
  transition: background-color 0.3s ease, color 0.3s ease;
}

.grain-overlay {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  opacity: 0.035;
  pointer-events: none;
  background-image: radial-gradient(#000 1px, transparent 1px);
  background-size: 4px 4px;
  z-index: 999;
}

.calculator-wrapper {
  width: 100%;
  max-width: 1100px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ==========================================================================
   HEADER
   ========================================================================== */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 4px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.swiss-cross {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  background-color: var(--swiss-red);
  color: #FFFFFF;
  font-size: 24px;
  font-weight: 900;
  border-radius: 6px;
  box-shadow: 0 4px 12px rgba(230, 57, 46, 0.3);
}

.brand-title {
  font-family: var(--font-display);
  font-size: 1.4rem;
  letter-spacing: -0.03em;
  font-weight: 600;
  line-height: 1.1;
}

.brand-title b {
  font-weight: 800;
  color: var(--swiss-red);
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  color: var(--text-secondary);
  margin-top: 2px;
}

.badge-group {
  display: flex;
  gap: 8px;
}

.btn-pill {
  background: var(--bg-card);
  border: 1px solid var(--border-hairline);
  padding: 6px 12px;
  border-radius: 30px;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  box-shadow: var(--shadow-bento);
  transition: var(--transition-fast);
}

.btn-pill:hover {
  border-color: var(--border-strong);
  color: var(--text-primary);
  transform: translateY(-1px);
}

.btn-pill .pill-val {
  font-weight: 700;
  color: var(--text-primary);
}

.btn-pill.active .pill-val {
  color: var(--swiss-red);
}

/* ==========================================================================
   BENTO CONTAINER & CARDS
   ========================================================================== */
.bento-container {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 16px;
}

.bento-card {
  background-color: var(--bg-card);
  border-radius: var(--card-radius);
  border: 1px solid var(--border-hairline);
  box-shadow: var(--shadow-bento);
  padding: 20px;
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

.card-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--text-secondary);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-num {
  color: var(--swiss-red);
  font-weight: 900;
}

/* 1. BENTO HERO DISPLAY (Span 8 Cols) */
.bento-display {
  grid-column: span 8;
  padding: 24px;
  justify-content: space-between;
  gap: 18px;
  background: linear-gradient(145deg, var(--bg-card) 0%, var(--bg-screen) 100%);
}

.display-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.status-tags {
  display: flex;
  gap: 6px;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 4px;
  background: rgba(0, 0, 0, 0.05);
  color: var(--text-tertiary);
  border: 1px solid transparent;
  transition: var(--transition-fast);
}

body.theme-dark .tag {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-secondary);
}

.tag.tag-active {
  background: var(--swiss-red);
  color: #FFFFFF !important;
}

.tag-memory {
  color: var(--text-secondary);
  border-color: var(--border-hairline);
}

.btn-icon {
  background: transparent;
  border: 1px solid var(--border-hairline);
  color: var(--text-secondary);
  width: 28px;
  height: 28px;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  position: relative;
  transition: var(--transition-fast);
}

.btn-icon:hover {
  background: var(--bg-card);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.copy-tooltip {
  position: absolute;
  top: -28px;
  right: 0;
  background: var(--text-primary);
  color: var(--bg-canvas);
  font-family: var(--font-mono);
  font-size: 0.65rem;
  padding: 3px 7px;
  border-radius: 4px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
  white-space: nowrap;
}

.copy-tooltip.show { opacity: 1; }

.display-screen {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
  padding: 16px 20px;
  background: var(--bg-screen);
  border-radius: 12px;
  border: 1px inset var(--border-hairline);
  min-height: 100px;
}

.screen-history-line {
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--text-secondary);
  word-break: break-all;
  text-align: right;
  min-height: 1.4em;
  opacity: 0.85;
}

.screen-main-line {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  width: 100%;
  overflow-x: auto;
  scrollbar-width: none;
}

.screen-main-line::-webkit-scrollbar { display: none; }

.screen-cursor {
  display: inline-block;
  width: 3px;
  height: 2.2rem;
  background-color: var(--swiss-red);
  margin-right: 4px;
  animation: blink 1s infinite;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

.screen-value {
  font-family: var(--font-display);
  font-size: 2.8rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  white-space: nowrap;
}

.display-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-tertiary);
  letter-spacing: 0.06em;
}

/* 2. BENTO TAPE HISTORY (Span 4 Cols) */
.bento-history {
  grid-column: span 4;
  justify-content: space-between;
}

.history-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.btn-text {
  background: transparent;
  border: none;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  font-weight: 700;
  color: var(--text-tertiary);
  cursor: pointer;
  letter-spacing: 0.05em;
  transition: color 0.15s ease;
}

.btn-text:hover { color: var(--swiss-red); }

.history-feed {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 10px;
  overflow-y: auto;
  max-height: 220px;
  padding-right: 4px;
  scrollbar-width: thin;
}

.history-item {
  background: rgba(0, 0, 0, 0.02);
  border: 1px solid var(--border-hairline);
  padding: 8px 12px;
  border-radius: 8px;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  cursor: pointer;
  transition: var(--transition-fast);
}

body.theme-dark .history-item {
  background: rgba(255, 255, 255, 0.03);
}

.history-item:hover {
  border-color: var(--swiss-red);
  background: rgba(230, 57, 46, 0.08);
}

.hist-expr {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.hist-res {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.history-empty {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-tertiary);
  text-align: center;
  margin: auto;
  font-style: italic;
}

/* 3. BENTO SCIENTIFIC PANEL (Span 5 Cols) */
.bento-scientific {
  grid-column: span 5;
}

.sci-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

/* 4. BENTO NUMPAD (Span 7 Cols) */
.bento-numpad {
  grid-column: span 7;
}

.num-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 12px;
}

/* 5. BENTO CONSTANTS (Span 12 Cols) */
.bento-constants {
  grid-column: span 12;
  padding: 16px 20px;
}

.constants-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 12px;
}

.btn-constant {
  background: var(--bg-card);
  border: 1px solid var(--border-hairline);
  padding: 10px 14px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.02);
  transition: var(--transition-fast);
}

.btn-constant:hover {
  border-color: var(--swiss-red);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(230, 57, 46, 0.15);
}

.const-sym {
  font-family: var(--font-typewriter);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--swiss-red);
}

.const-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--text-secondary);
}

.const-meta b {
  font-family: var(--font-sans);
  color: var(--text-primary);
  font-size: 0.75rem;
}

/* ==========================================================================
   TYPEWRITER MECHANICAL KEYCAP DESIGN (VARIABLE-DRIVEN)
   ========================================================================== */
.tw-key {
  position: relative;
  aspect-ratio: 1 / 1;
  border-radius: 50%;
  border: none;
  background: transparent;
  cursor: pointer;
  padding: 0;
  outline: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

/* Outer concentric metallic rim */
.tw-key::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  border-radius: 50%;
  background: linear-gradient(145deg, var(--key-num-rim-top) 0%, var(--key-num-rim-bot) 100%);
  box-shadow: 0 5px 0 var(--key-num-shadow), 0 8px 12px rgba(0, 0, 0, 0.25);
  transition: all 0.08s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Inner concave key dish with typewriter stamp */
.key-inner {
  position: absolute;
  top: 3px; left: 3px; right: 3px; bottom: 7px;
  border-radius: 50%;
  background: radial-gradient(circle at 45% 40%, var(--key-num-dish-top) 0%, var(--key-num-dish-bot) 100%);
  color: var(--key-num-text);
  font-family: var(--font-typewriter);
  font-size: 1.3rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: inset 0 2px 3px rgba(255, 255, 255, 0.2), inset 0 -2px 4px rgba(0, 0, 0, 0.3);
  transition: all 0.08s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 2;
}

/* Mechanical Key Depression Active State */
.tw-key:active::before,
.tw-key.key-pressed::before {
  box-shadow: 0 1px 0 var(--key-num-shadow), 0 2px 4px rgba(0, 0, 0, 0.3);
  transform: translateY(4px);
}

.tw-key:active .key-inner,
.tw-key.key-pressed .key-inner {
  transform: translateY(4px);
  box-shadow: inset 0 2px 6px rgba(0, 0, 0, 0.5);
}

/* VARIANT: Function / Scientific Keys */
.tw-key-fn::before {
  background: linear-gradient(145deg, var(--key-fn-rim-top) 0%, var(--key-fn-rim-bot) 100%);
  box-shadow: 0 4px 0 var(--key-fn-shadow), 0 6px 10px rgba(0, 0, 0, 0.2);
}
.tw-key-fn .key-inner {
  background: radial-gradient(circle at 45% 40%, var(--key-fn-dish-top) 0%, var(--key-fn-dish-bot) 100%);
  color: var(--key-fn-text);
  font-size: 0.95rem;
  font-family: var(--font-mono);
  font-weight: 600;
}
.tw-key-fn:active::before,
.tw-key-fn.key-pressed::before {
  box-shadow: 0 1px 0 var(--key-fn-shadow);
}

/* VARIANT: Operators */
.tw-key-op::before {
  background: linear-gradient(145deg, var(--key-op-rim-top) 0%, var(--key-op-rim-bot) 100%);
  box-shadow: 0 5px 0 var(--key-op-shadow), 0 8px 14px rgba(0, 0, 0, 0.3);
}
.tw-key-op .key-inner {
  background: radial-gradient(circle at 45% 35%, var(--key-op-dish-top) 0%, var(--key-op-dish-bot) 100%);
  color: var(--key-op-text);
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
}
.tw-key-op:active::before,
.tw-key-op.key-pressed::before {
  box-shadow: 0 1px 0 var(--key-op-shadow);
}

/* VARIANT: Swiss Red (AC Key) */
.tw-key-red::before {
  background: linear-gradient(145deg, #FF6B60 0%, var(--swiss-red) 100%);
  box-shadow: 0 5px 0 #8F1911, 0 8px 14px rgba(230, 57, 46, 0.35);
}
.tw-key-red .key-inner {
  background: radial-gradient(circle at 45% 35%, #FF5246 0%, var(--swiss-red) 100%);
  color: #FFFFFF !important;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 1rem;
}
.tw-key-red:active::before,
.tw-key-red.key-pressed::before {
  box-shadow: 0 1px 0 #8F1911;
}

/* VARIANT: Amber Delete */
.tw-key-orange::before {
  background: linear-gradient(145deg, #FBBF24 0%, var(--amber-warn) 100%);
  box-shadow: 0 5px 0 #78350F, 0 8px 14px rgba(217, 119, 6, 0.3);
}
.tw-key-orange .key-inner {
  background: radial-gradient(circle at 45% 35%, #F59E0B 0%, var(--amber-warn) 100%);
  color: #FFFFFF !important;
  font-size: 1.1rem;
}
.tw-key-orange:active::before,
.tw-key-orange.key-pressed::before {
  box-shadow: 0 1px 0 #78350F;
}

/* VARIANT: Equals Key (Bold Swiss Accent) */
.tw-key-equals::before {
  background: linear-gradient(145deg, #FF6B60 0%, var(--swiss-red) 100%);
  box-shadow: 0 6px 0 #8F1911, 0 10px 18px rgba(230, 57, 46, 0.4);
}
.tw-key-equals .key-inner {
  background: radial-gradient(circle at 45% 35%, #FF4D40 0%, var(--swiss-red) 100%);
  color: #FFFFFF !important;
  font-size: 1.6rem;
  font-weight: 800;
}
.tw-key-equals:active::before,
.tw-key-equals.key-pressed::before {
  box-shadow: 0 1px 0 #8F1911;
}

/* Memory Keys */
.tw-key-mem .key-inner {
  font-size: 0.85rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
}

/* ==========================================================================
   FOOTER
   ========================================================================== */
.app-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0 4px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-tertiary);
}

.footer-left {
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer-dot { color: var(--swiss-red); }

.footer-right {
  display: flex;
  gap: 12px;
}

.shortcut-tip kbd {
  background: var(--bg-card);
  border: 1px solid var(--border-hairline);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--text-primary);
  font-weight: 700;
}

/* ==========================================================================
   RESPONSIVE DESIGN
   ========================================================================== */
@media (max-width: 960px) {
  .bento-display { grid-column: span 12; }
  .bento-history { grid-column: span 12; }
  .bento-scientific { grid-column: span 12; }
  .bento-numpad { grid-column: span 12; }
  .constants-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 600px) {
  .constants-grid { grid-template-columns: repeat(2, 1fr); }
  .screen-value { font-size: 2.1rem; }
  .app-footer { flex-direction: column; gap: 8px; text-align: center; }
  .footer-right { flex-wrap: wrap; justify-content: center; }
}