:root {
  --color-dark-blue: #1d2b53;
  --color-dark-purple: #222034;
  --color-purple: #3f3f74;
  --color-red: #ff004d;
  --color-pink: #ff77a8;
  --color-orange: #ffec27;
  --color-yellow: #ffcc00;
  --color-green: #00e436;
  --color-blue: #29adff;
  --color-light-blue: #83769c;
  --color-white: #fff1e8;
  --color-black: #000000;
  
  --border-radius-sm: 6px;
  --border-radius-md: 10px;
  --border-radius-lg: 16px;
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 12px;
  --spacing-lg: 16px;
  --spacing-xl: 24px;
  --spacing-xxl: 32px;
  
  --shadow-sm: 0 3px 0;
  --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.6);
  --shadow-inner: inset 0 2px 4px rgba(0, 0, 0, 0.3);
  
  --font-pixel: 'Press Start 2P', monospace;
  --font-size-xs: 0.7rem;
  --font-size-small: 0.8rem;
  --font-size-normal: 1rem;
  --font-size-large: 1.75rem;
  
  --transition-fast: 0.1s;
  --transition-medium: 0.2s;
  --transition-slow: 0.3s;
  
  --container-max-width: 360px;
  --display-min-width: 240px;
  --button-min-size: 56px;
  --button-min-size-mobile: 42px;
}

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
}

body {
  background: var(--color-dark-blue);
  background-image: radial-gradient(var(--color-light-blue) 1px, transparent 1px);
  background-size: 20px 20px;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-pixel);
  padding: var(--spacing-md);
  color: var(--color-white);
}

.calculator-container {
  background: var(--color-dark-purple);
  border: var(--spacing-sm) solid var(--color-red);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-lg), 
              0 0 0 var(--spacing-xs) var(--color-pink), 
              0 0 0 calc(var(--spacing-xs) * 2) var(--color-blue);
  padding: var(--spacing-xxl) var(--spacing-xl);
  display: flex;
  justify-content: center;
  transform: rotate(-1deg);
  position: relative;
  max-width: var(--container-max-width);
  width: 100%;
  animation: fadeIn 0.6s ease-out;
}

.calculator-container::before {
  content: "CALC-8";
  position: absolute;
  top: -10px;
  right: 20px;
  background: var(--color-orange);
  color: var(--color-dark-purple);
  font-size: var(--font-size-small);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius-sm);
  transform: rotate(3deg);
  box-shadow: var(--shadow-sm) var(--color-dark-purple);
  z-index: 1;
  animation: wiggle 2s ease-in-out infinite;
}

.calculator {
  background: var(--color-purple);
  background-image: linear-gradient(
    45deg, 
    var(--color-purple) 25%, 
    var(--color-light-blue) 25%, 
    var(--color-light-blue) 50%, 
    var(--color-purple) 50%, 
    var(--color-purple) 75%, 
    var(--color-light-blue) 75%, 
    var(--color-light-blue) 100%
  );
  background-size: 8px 8px;
  border-radius: var(--border-radius-md);
  padding: var(--spacing-xl) var(--spacing-lg) var(--spacing-lg) var(--spacing-lg);
  box-shadow: var(--shadow-md);
  border: var(--spacing-xs) solid var(--color-white);
  width: 100%;
}

.display {
  background: var(--color-white);
  color: var(--color-dark-blue);
  font-size: var(--font-size-large);
  padding: var(--spacing-lg) var(--spacing-md);
  margin-bottom: var(--spacing-xl);
  border-radius: var(--border-radius-sm);
  text-align: right;
  font-family: var(--font-pixel);
  letter-spacing: 2px;
  box-shadow: var(--shadow-sm) var(--color-orange), 
              inset 0 2px 5px rgba(0, 0, 0, 0.2);
  min-width: var(--display-min-width);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  border: 2px solid var(--color-dark-blue);
  position: relative;
  transition: all var(--transition-fast);
  height: 70px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.display::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(to right, 
              var(--color-green), 
              var(--color-blue), 
              var(--color-pink));
  opacity: 0.5;
}

.display::after {
  content: attr(data-operation);
  position: absolute;
  top: 8px;
  left: 8px;
  font-size: var(--font-size-xs);
  color: var(--color-purple);
  opacity: 0.7;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(5, auto);
  gap: var(--spacing-md);
  max-width: 100%;
  grid-template-areas:
    "seven eight nine divide"
    "four five six multiply"
    "one two three subtract"
    "zero dot equals add"
    "clear clear equals add";
}

.btn {
  background: var(--color-blue);
  color: var(--color-white);
  font-family: var(--font-pixel);
  font-size: var(--font-size-normal);
  border: 2px solid var(--color-white);
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-sm) var(--color-green);
  padding: var(--spacing-md) 0;
  cursor: pointer;
  transition: transform var(--transition-fast),
              background-color var(--transition-fast),
              box-shadow var(--transition-fast);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  position: relative;
  overflow: hidden;
  min-width: var(--button-min-size);
  min-height: var(--button-min-size);
  display: flex;
  align-items: center;
  justify-content: center;
  transform: rotate(-1deg);
}

.btn::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(to bottom, rgba(255,255,255,0.2), transparent);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.btn:active {
  background: var(--color-green);
  transform: translateY(3px) rotate(0deg);
  box-shadow: none;
}

.btn:hover {
  filter: brightness(1.2);
  transform: translateY(1px) rotate(0deg);
}

.btn:hover::before {
  opacity: 1;
}

.btn:focus-visible {
  outline: 3px solid var(--color-orange);
  outline-offset: 2px;
  animation: pulse 1s infinite;
}

.btn.op {
  background: var(--color-pink);
  color: var(--color-dark-blue);
  border-color: var(--color-orange);
  box-shadow: var(--shadow-sm) var(--color-orange);
  font-weight: bold;
  transform: rotate(2deg);
}

.btn.eq {
  background: var(--color-orange);
  color: var(--color-dark-blue);
  border-color: var(--color-red);
  box-shadow: var(--shadow-sm) var(--color-red);
  font-weight: bold;
  grid-area: equals;
  transform: rotate(0deg);
}

.btn.clr {
  background: var(--color-red);
  color: var(--color-white);
  border-color: var(--color-blue);
  box-shadow: var(--shadow-sm) var(--color-dark-blue);
  font-weight: bold;
  grid-area: clear;
  transform: rotate(0deg);
}

.btn.op:active {
  background: var(--color-yellow);
}

.btn.eq:active {
  background: var(--color-green);
}

.btn.clr:active {
  background: var(--color-dark-purple);
}

.btn[data-value="0"] { grid-area: zero; }
.btn[data-value="1"] { grid-area: one; }
.btn[data-value="2"] { grid-area: two; }
.btn[data-value="3"] { grid-area: three; }
.btn[data-value="4"] { grid-area: four; }
.btn[data-value="5"] { grid-area: five; }
.btn[data-value="6"] { grid-area: six; }
.btn[data-value="7"] { grid-area: seven; }
.btn[data-value="8"] { grid-area: eight; }
.btn[data-value="9"] { grid-area: nine; }
.btn[data-value="."] { grid-area: dot; }
.btn[data-op="/"] { grid-area: divide; }
.btn[data-op="*"] { grid-area: multiply; }
.btn[data-op="-"] { grid-area: subtract; }
.btn[data-op="+"] { grid-area: add; }

.btn:nth-child(odd) {
  transform: rotate(1deg);
}
.btn:nth-child(even) {
  transform: rotate(-1deg);
}

@media (max-width: 480px) {
  html {
    font-size: 14px;
  }
  
  .calculator-container {
    padding: var(--spacing-lg) var(--spacing-md);
    transform: rotate(0deg);
  }
  
  .calculator {
    padding: var(--spacing-lg) var(--spacing-md) var(--spacing-md) var(--spacing-md);
  }
  
  .buttons {
    gap: var(--spacing-sm);
  }
  
  .btn {
    font-size: var(--font-size-small);
    padding: var(--spacing-sm) 0;
    min-width: var(--button-min-size-mobile);
    min-height: var(--button-min-size-mobile);
    transform: rotate(0deg) !important;
  }
  
  .display {
    font-size: 1.4rem;
    padding: var(--spacing-md) var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
    min-width: auto;
    height: 60px;
  }
  
  .calculator-container::before {
    font-size: var(--font-size-xs);
    padding: 2px 4px;
  }
}

@media (max-width: 320px) {
  html {
    font-size: 12px;
  }
  
  .btn {
    min-width: 36px;
    min-height: 36px;
  }
  
  .display {
    height: 50px;
    font-size: 1.2rem;
  }
}

@media (prefers-color-scheme: dark) {
  .display {
    color: var(--color-dark-blue);
  }
}

@keyframes fadeIn {
  from { 
    opacity: 0; 
    transform: translateY(-10px) rotate(-1deg); 
  }
  to { 
    opacity: 1; 
    transform: translateY(0) rotate(-1deg); 
  }
}

@keyframes buttonPress {
  0% { transform: scale(1); }
  50% { transform: scale(0.95); }
  100% { transform: scale(1); }
}

.btn.pressed {
  animation: buttonPress 0.2s ease-out;
}

@keyframes displayUpdate {
  0% { background-color: var(--color-white); }
  50% { background-color: var(--color-green); }
  100% { background-color: var(--color-white); }
}

.display.updated {
  animation: displayUpdate 0.2s ease-out;
}

@keyframes pulse {
  0% {
    box-shadow: 0 0 0 0 rgba(255, 236, 39, 0.7);
  }
  70% {
    box-shadow: 0 0 0 6px rgba(255, 236, 39, 0);
  }
  100% {
    box-shadow: 0 0 0 0 rgba(255, 236, 39, 0);
  }
}

@keyframes wiggle {
  0%, 100% { transform: rotate(3deg); }
  50% { transform: rotate(5deg); }
}

.btn:focus {
  outline: none;
  box-shadow: var(--shadow-sm) var(--color-green), 
              0 0 0 2px var(--color-orange);
}

.display.error {
  background-color: var(--color-red);
  color: var(--color-white);
  animation: shake 0.4s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-5px); }
  40%, 80% { transform: translateX(5px); }
}

.btn:active::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.1);
  border-radius: inherit;
}