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

/* Remove default padding */
ul[class],
ol[class] {
  padding: 0;
}

/* remove default margin */
body,
h1,
h2,
h3,
h4,
p,
ul[class],
ol[class],
li,
figure,
figcaption,
blockquote,
dl,
dd {
  margin: 0;
}

/* set core body defaults */
body {
  min-height: 100vh;
  scroll-behavior: smooth;
  text-rendering: optimizeSpeed;
  line-height: 1;
}

/* remove list styles on ul, ol elements with a class attribute */
ul[class],
ol[class] {
  list-style: none;
}

/* a elements that don't have a class get default styles */
a:not([class]) {
  text-decoration-skip-ink: auto;
}

/* make images easier to work with */
img {
  max-width: 100%;
  display: block;
}

/* inherit font for inputs and buttons */
input,
button,
textarea,
select {
  font: inherit;
}

/* reset default button styles */
button {
  background: transparent;
  border: none;
  padding: 0;
  margin: 0;
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  line-height: inherit;
}

/* remove all animations, transitions, and smooth scrolling for people that prefer not to see them */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* Theme 1 */
:root {
  --bg-main: hsl(222, 26%, 31%);
  --bg-toggle: hsl(223, 31%, 20%);
  --bg-screen: hsl(224, 36%, 15%);
  --key-toogle-equal: hsl(6, 63%, 50%);
  --key-toogle-equal-hover: hsl(7, 93%, 66%);
  --key-toogle-equal-shadow: hsl(6, 70%, 34%);
  --key-reset-delete: hsl(225, 21%, 49%);
  --key-reset-delete-hover: hsl(225, 51%, 76%);
  --key-reset-delete-shadow: hsl(224, 28%, 35%);
  --key-num-opertor: hsl(30, 25%, 89%);
  --key-num-opertor-hover: hsl(0, 0%, 100%);
  --key-num-opertor-shadow: hsl(28, 16%, 65%);
  --text-white: hsl(0, 0%, 100%);
  --text-body: hsl(0, 0%, 100%);
  --text-num: hsl(221, 14%, 31%);
}

/* Theme 2 */
:root.theme2 {
  --bg-main: hsl(0, 0%, 90%);
  --bg-toggle: hsl(0, 5%, 81%);
  --bg-screen: hsl(0, 0%, 93%);
  --key-toogle-equal: hsl(25, 98%, 40%);
  --key-toogle-equal-hover: hsl(25, 100%, 60%);
  --key-toogle-equal-shadow: hsl(25, 99%, 27%);
  --key-reset-delete: hsl(185, 42%, 37%);
  --key-reset-delete-hover: hsl(185, 41%, 56%);
  --key-reset-delete-shadow: hsl(185, 58%, 25%);
  --key-num-opertor: hsl(45, 7%, 89%);
  --key-num-opertor-hover: hsl(0, 0%, 100%);
  --key-num-opertor-shadow: hsl(35, 11%, 61%);
  --text-body: hsl(60, 10%, 19%);
  --text-num: hsl(60, 10%, 19%);
}

/* Theme 3 */
:root.theme3 {
  --bg-main: hsl(268, 75%, 9%);
  --bg-toggle: hsl(268, 71%, 12%);
  --bg-screen: hsl(268, 71%, 12%);
  --key-toogle-equal: hsl(176, 100%, 44%);
  --key-toogle-equal-hover: hsl(176, 89%, 75%);
  --key-toogle-equal-shadow: hsl(177, 92%, 70%);
  --key-reset-delete: hsl(281, 89%, 26%);
  --key-reset-delete-hover: hsl(280, 56%, 44%);
  --key-reset-delete-shadow: hsl(285, 91%, 52%);
  --key-num-opertor: hsl(268, 47%, 21%);
  --key-num-opertor-hover: hsl(267, 54%, 44%);
  --key-num-opertor-shadow: hsl(290, 70%, 36%);
  --text-body: hsl(52, 100%, 62%);
  --text-num: hsl(52, 100%, 62%);
}

body {
  font-family: "League Spartan", sans-serif;
  font-weight: 700;
  font-size: 32px;

  background-color: var(--bg-main);
  color: var(--text-body);

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px 0;

  user-select: none;

  transition:
    background 300ms ease-in-out,
    color 300ms ease-in-out;
}

.calculator {
  width: 100%;
  max-width: 588px;
  padding: 24px;
}

.calc-header {
  display: flex;
  justify-content: space-between;
  align-items: end;

  margin-bottom: 32px;
}

.logo {
  letter-spacing: -0.01em;
}

.theme-toggle {
  display: flex;
  flex-direction: column;
  gap: 4px;
  align-items: end;
}

.theme-number {
  display: flex;
  gap: 16px;
  padding: 0 6px;
}

.theme-number span {
  font-size: 16px;
}

.theme-container {
  display: flex;
  gap: 20px;
  align-items: center;
}

.theme-container span {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.theme-option {
  display: flex;
  gap: 4px;
  padding: 4px;

  width: 70px;
  border-radius: 12px;

  background: var(--bg-toggle);

  transition: background 300ms ease-in-out;
}

.theme-btn {
  width: 18px;
  height: 18px;

  border-radius: 100%;

  background: var(--key-toogle-equal);

  transition: background 300ms ease-in-out;
}

.theme-btn:hover {
  background: var(--key-toogle-equal-hover);
}

.display {
  background: var(--bg-screen);

  border-radius: 12px;
  padding: 36px 32px 32px;
  margin-bottom: 24px;

  transition: background 300ms ease-in-out;
}

.result {
  color: var(--text-body);

  text-align: right;
  font-size: 56px;
  letter-spacing: -0.015em;

  width: 100%;

  border: none;
  outline: none;
  background: transparent;
  padding: 0;

  cursor: auto;
}

.keypad-container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(5, 1fr);

  gap: 28px 24px;

  background: var(--bg-toggle);
  border-radius: 12px;
  padding: 32px;

  transition: backgroud 300ms ease-in-out;
}

.keypad-container button {
  border-radius: 10px;

transition: backgroud 300ms ease-in-out;  
}

.keypad-container button:active{
    transform: translateY(5px);
    box-shadow: 0px 0px 0px 0px transparent;

    transform: transform 100ms ease-in, box-shaadow 100ms ease-in;
}

.num-btn,
.operator-btn {
  width: 100%;
  padding: 10px 0;
  background: var(--key-num-opertor);

  font-size: 40px;
  letter-spacing: -0.02em;

  color: var(--text-num);

  box-shadow: 0px 5px 0px 0px var(--key-num-opertor-shadow);
}

.num-btn:hover,
.operator-btn:hover {
  background: var(--key-num-opertor-hover);
}

.reset-btn {
    grid-column-start: 1;
    grid-column-end: 3;
}

.equal-btn {
    grid-column-start: 3;
    grid-column-end: 5;

    font-size: 40px;

    background: var(--key-toogle-equal);
    color: var(--text-white);

    box-shadow: 0px 5px 0px 0px var(--key-toogle-equal-shadow);
}

.equal-btn:hover{
    background: var(--key-toogle-equal-hover);
}

.reset-btn,
.delete-btn {
    font-size: 28px;

    background: var(--key-reset-delete);
    color: var(--text-white);

    box-shadow: 0px 5px 0px 0px var(--key-reset-delete-shadow);
}

.reset-btn:hover,
.delete-btn:hover {
    background: var(--key-reset-delete-hover);
}

@media only screen and (max-width: 480px) {
    .display {
        padding: 24px;
    }

    .result{
        font-size: 40px;
    }

    .keypad-container{
        gap: 16px 12px;
    }

    .num-btn,.equal-btn{
        font-size: 32px;
        padding: 14px 0;
    }

    .reset-btn, .delete-btn{
        font-size: 20px;
    }
}

.attribution {
  font-size: 13px;
  text-align: center;
  margin-top: 16px;
  color: var(--text-body);
}

.attribution a {
  color: var(--key-toogle-equal);
}