:root {
  --bg: hsl(222, 26%, 31%);
  --key-text: hsla(0, 0%, 100%, 0.822);
  --bg-hover: hsla(0, 0%, 100%, 0.927);
  --key-bg: hsl(224, 36%, 15%);
  --text: hsl(221, 14%, 31%);
  --accent: hsl(6, 63%, 50%);
  --sc: hsl(225, 21%, 49%);
  --accent-hover: hsla(6, 84%, 56%, 0.979);
  --sc-hover: hsl(226, 26%, 62%);
  --mobile-key: hsl(0, 0%, 90%);
}

* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
}
html {
  font-size: 62.5%;
  overflow-x: hidden;
  /*does NOT work on safari(browser)*/
  scroll-behavior: smooth;
}

body {
  /* font-family: 'Rubik', sans-serif; */
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  line-height: 1;
  font-weight: 400;
  color: var(--text);
  background-color: var(--bg);
}
.container {
  max-width: 23rem;
  margin: 10rem auto;
}

.theme-switch {
  text-align: right;
  font-size: 0.75rem;
  text-transform: uppercase;
  color: var(--text);
}

.toggle-wrapper {
  display: inline-block;
  transform: translateY(-1.4rem);
}
.theme {
  margin-right: 1rem;
  font-size: 0.5rem;
  color: #fff;
}
.theme-numbers {
  display: flex;
  align-items: center;
  gap: 0.2rem;
  /* justify-content: space-between; */
  padding: 0 5px;
  margin-bottom: 5px;
  font-size: 0.6rem;
}

.theme-numbers span {
  width: 10px;
  text-align: center;
  color: #fff;
}

.toggle {
  position: relative;
  /* background: var(--toggle-bg); */
  border-radius: 20px;
  height: 10px;
  width: 38px;
  display: flex;
  justify-content: space-between;
  padding: 0 5px;
  align-items: center;
  background-color: hsl(223, 31%, 20%);
}

/* Position each clickable area */
.toggle input#theme-1 {
  left: 0;
}
.toggle input#theme-2 {
  left: 33.3%;
}
.toggle input#theme-3 {
  left: 66.6%;
}

/* Hide radio buttons */
.toggle input[type='radio'] {
  opacity: 0;
  position: absolute;
}

/* Circle (slider knob) */
.slider {
  position: absolute;
  top: 2px;
  left: 5px;
  height: 7.5px;
  width: 7.5px;
  /* background: var(--accent-color); */
  background-color: rgb(192, 58, 9);
  /* background-color: rgb(169, 72, 37); */

  border-radius: 50%;
  transition: transform 0.3s ease;
}

/* Move the circle when checked */
#theme-2:checked ~ .slider {
  transform: translateX(14px);
}
#theme-3:checked ~ .slider {
  transform: translateX(25px);
}
.top-bar {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  /* margin-bottom: 1rem; */
}
.calc {
  color: #fff;
  font-weight: 800;
}

#calc-box {
  width: 100%;
  height: 5rem;
  font-family: 'Rubik', sans-serif;
  text-align: right;
  padding: 0 1.5rem;
  background-color: hsl(223, 31%, 20%);
  color: #fff;
  border: none;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 2.2rem;
}

#calc-box.error {
  color: hsl(0, 100%, 70%);
  background-color: hsl(0, 0%, 20%);
  font-weight: bold;
  /* font-size: 1rem; */
  text-transform: uppercase;
  transition: all 0.3s ease;
  animation: shake 0.3s ease;
}

@keyframes shake {
  0% {
    transform: translateX(0);
  }
  20% {
    transform: translateX(-3px);
  }
  40% {
    transform: translateX(3px);
  }
  60% {
    transform: translateX(-3px);
  }
  80% {
    transform: translateX(3px);
  }
  100% {
    transform: translateX(0);
  }
}
/* Keep styles consistent on focus, hover, and autofill */
#calc-box:focus,
#calc-box:hover {
  background-color: hsl(223, 31%, 20%);
  color: #fff;
  outline: none;
}

/* Tame autofill background on Chrome */
#calc-box:-webkit-autofill {
  -webkit-box-shadow: 0 0 0 1000px hsl(223, 31%, 20%) inset !important;
  -webkit-text-fill-color: #fff !important;
}

.keys-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  align-items: center;
  margin-top: 1rem;
  gap: 1rem;
  border-radius: 5px;
  background-color: var(--key-bg);
  padding: 1.5rem 1.5rem;
}
.keys,
.key-del,
.key-reset,
.key-equal {
  font-size: 1.3rem;
  font-weight: 800;
  height: 2.5rem;
  border-radius: 5px;
  border: none;
  color: var(--text);
  background-color: var(--key-text);
}

.keys:hover {
  background-color: var(--bg-hover);
}

.key-del {
  background-color: var(--sc);
  text-transform: uppercase;
  color: #fff;
  font-size: 0.9rem;
}

.key-del:hover {
  background-color: var(--sc-hover);
}

.key-reset {
  grid-column: span 2;
  background-color: var(--sc);
  color: #fff;
  text-transform: uppercase;
  font-size: 0.9rem;
  box-shadow: 0px 3px 5px rgba(85, 85, 85, 0.5); /* subtle gray tone */
}

.key-reset:hover {
  background-color: var(--sc-hover);
}

.key-equal {
  grid-column: span 2;
  /* background-color: hsl(6, 63%, 50%); */
  background-color: var(--accent);
  color: #fff;
  font-size: 1rem;
  box-shadow: 0px 3px 5px rgba(85, 85, 85, 0.4); /* subtle gray tone */
}

.key-equal:hover {
  background-color: var(--accent-hover);
}

/*themes*/

.theme-2 {
  --bg: #ddd;
  --text: hsl(60, 10%, 20%);
  --bg-hover: hsla(0, 0%, 100%, 0.927);
  --key-bg: hsl(0, 5%, 81%);
  --key-text: hsl(0, 0%, 93%); /*hover*/
  --accent: hsl(25, 98%, 40%);
  --sc: hsl(185, 58%, 25%);
  --accent-hover: hsl(25, 91%, 52%);
  --sc-hover: hsl(185, 50%, 52%);
}

.theme-3 {
  --bg: hsl(268, 75%, 9%);
  --text: hsl(52, 100%, 62%);
  --bg-hover: hsl(285, 63%, 48%);
  --key-bg: hsla(268, 66%, 14%, 0.93);
  --key-text: hsl(281, 72%, 18%);
  --accent: hsl(176, 100%, 44%);
  --sc: hsla(285, 91%, 52%, 0.644);
  --accent-hover: hsl(177, 92%, 70%);
  --sc-hover: hsl(285, 91%, 52%);
}

.theme-3 .key,
.theme-3 .key-del,
.theme-3 .key-reset {
  box-shadow: 0 2px 1px hsla(268, 80%, 70%, 0.5); /* soft purple glow downward */
}

.theme-3 .key-equal {
  color: #000;
}

/* Box Shadow explained 

box-shadow: offset-x offset-y blur-radius spread-radius color;
Here’s what each part means:

offset-x → how far the shadow moves horizontally

0 = no left or right shift

positive = right

negative = left

offset-y → how far the shadow moves vertically

0 = no top or bottom shift

positive = shadow moves down

negative = shadow moves up

blur-radius → how soft the shadow edges are

0 = sharp

higher = more blurry/soft

spread-radius (optional) → size of the shadow itself

positive = makes it bigger

negative = shrinks it

color → any valid CSS color

*/