:root {
  /* Light Theme */
  --light-bg: hsl(0, 0%, 90%);
  --light-text: hsl(60, 10%, 19%);
  --light-display-bg: hsl(0, 0%, 100%);
  --light-display-text: hsl(0, 0%, 0%);
  --light-btn-bg: hsl(45, 7%, 89%);
  --light-btn-shadow: hsl(35, 11%, 61%);
  --light-del-bg: hsl(185, 42%, 37%);
  --light-del-shadow: hsl(185, 58%, 25%);
  --light-equal-bg: hsl(25, 98%, 40%);
  
  /* Dark Theme */
  --dark-bg: hsl(222, 26%, 20%);
  --dark-text: hsl(221, 14%, 80%);
  --dark-display-bg: hsl(224, 32%, 30%);
  --dark-btn-bg: hsl(30, 25%, 89%);
  --dark-btn-shadow: hsl(28, 16%, 65%);
  --dark-del-bg: hsl(225, 21%, 49%);
  --dark-del-shadow: hsl(224, 28%, 35%);
  --dark-equal-bg: hsl(6, 63%, 50%);
  
  /* Blue Theme */
  --blue-bg: hsl(268, 75%, 9%);
  --blue-text: hsl(52, 100%, 62%);
  --blue-display-bg: hsl(268, 71%, 12%);
  --blue-btn-bg: hsl(268, 47%, 21%);
  --blue-btn-shadow: hsl(290, 70%, 36%);
  --blue-del-bg: hsl(281, 89%, 26%);
  --blue-del-shadow: hsl(285, 91%, 52%);
  --blue-equal-bg: hsl(176, 100%, 44%);
  
  /* Common */
  --transition: all 0.3s ease;
}

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

body {
  font-family: 'Cairo', sans-serif;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  background: var(--dark-bg);
  color: var(--dark-text);
  transition: var(--transition);
}

/* Theme Styles */
body[data-theme="light"] {
  background: var(--light-bg);
  color: var(--light-text);
}

body[data-theme="dark"] {
  background: var(--dark-bg);
  color: var(--dark-text);
}

body[data-theme="blue"] {
  background: var(--blue-bg);
  color: var(--blue-text);
}

.main-container {
  width: 600px;
  margin-top: 50px;
}

.head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.head h2 {
  font-size: 30px;
  font-weight: bold;
}

/* Theme Switch */
.theme-switch {
  position: relative;
  display: inline-block;
  width: 60px;
  height: 25px;
}

.slider {
  position: absolute;
  cursor: pointer;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: hsla(0, 0%, 38%, 0.116);
  transition: var(--transition);
  border-radius: 40px;
  display: flex;
  align-items: center;
  padding: 5px;
}

.slider span {
  width: 15px;
  height: 15px;
  border-radius: 50%;
  transition: var(--transition);
  position: absolute;
}

.slider[data-position="0"] span {
  left: 5px;
  background: var(--light-equal-bg);
}

.slider[data-position="1"] span {
  left: 20px;
  background: var(--dark-equal-bg);
}

.slider[data-position="2"] span {
  left: 40px;
  background: var(--blue-equal-bg);
}

/* Input Display */
.inp input {
  padding: 30px;
  width: 100%;
  border: none;
  border-radius: 10px;
  font-size: 50px;
  font-weight: 900;
  text-align: right;
  outline: none;
  transition: var(--transition);
  background: var(--dark-display-bg);
  color: white;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

body[data-theme="light"] .inp input {
  background: var(--light-display-bg);
  color: var(--light-display-text);
}

body[data-theme="dark"] .inp input {
  background: var(--dark-display-bg);
  color: white;
}

body[data-theme="blue"] .inp input {
  background: var(--blue-display-bg);
  color: var(--blue-text);
}

/* Calculator Body */
.content {
  background: hsl(223, 31%, 20%);
  margin: 30px 0;
  padding: 30px;
  border-radius: 20px;
  transition: var(--transition);
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

body[data-theme="light"] .content {
  background: hsl(0, 0%, 93%);
}

body[data-theme="blue"] .content {
  background: var(--blue-del-bg);
}

/* Calculator Buttons */
.calculator {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin-bottom: 20px;
}

.btn, .del, .c, .result {
  border: none;
  border-radius: 10px;
  font-size: 30px;
  font-weight: 900;
  padding: 15px 0;
  cursor: pointer;
  transition: var(--transition);
  transform-origin: center;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

.btn {
  background: var(--dark-btn-bg);
  color: var(--dark-text);
}

.del, .c {
  background: var(--dark-del-bg);
  color: white;
  font-size: 24px;
  text-transform: uppercase;
}

.result {
  background: var(--dark-equal-bg);
  color: white;
}

/* Hover Effects */
.btn:hover, .del:hover, .c:hover, .result:hover {
  transform: scale(1.05);
}

.btn:active, .del:active, .c:active, .result:active {
  transform: scale(0.98);
}

/* Theme-specific Button Styles */
body[data-theme="light"] .btn {
  background: var(--light-btn-bg);
  color: var(--light-text);
  box-shadow: 0 4px 8px var(--light-btn-shadow);
}

body[data-theme="light"] .del, 
body[data-theme="light"] .c {
  background: var(--light-del-bg);
  box-shadow: 0 4px 8px var(--light-del-shadow);
}

body[data-theme="blue"] .btn {
  background: var(--blue-btn-bg);
  color: var(--blue-text);
  box-shadow: 0 4px 8px var(--blue-btn-shadow);
}

body[data-theme="blue"] .del,
body[data-theme="blue"] .c {
  background: var(--blue-del-bg);
  box-shadow: 0 4px 8px var(--blue-del-shadow);
}

body[data-theme="blue"] .result {
  background: var(--blue-equal-bg);
}

/* Equal/Reset Row */
.equal {
  display: flex;
  gap: 20px;
}

.equal .c, .equal .result {
  width: 50%;
}

/* Responsive Design */
@media (max-width: 768px) {
  .main-container {
    width: 350px;
    margin-top: 30px;
  }
  
  .inp input {
    font-size: 32px;
    padding: 25px;
  }
  
  .content {
    padding: 20px;
  }
  
  .calculator {
    gap: 15px;
  }
  
  .btn, .del, .c, .result {
    font-size: 24px;
    padding: 12px 0;
  }
  
  .del, .c {
    font-size: 20px;
  }
}

@media (max-width: 480px) {
  .main-container {
    width: 90%;
  }
  
  .inp input {
    font-size: 28px;
    padding: 20px;
  }
  
  .btn, .del, .c, .result {
    font-size: 20px;
  }
}