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

:root {
  /* header */
  --bg-header: #1d1d1d;
  --bg-header-shadow: #202020;
  --sz-header-height: 6rem;

  --bg-navbar-toggle: #97c8ff;

  /* main */
  --bg: #303030;
  --fg: #7eb85a;
  --fg-number: #f76060;

  /* container */
  --bg-board: #1a1a1a;
  --bg-board-outline: #252525;

  /* snake */
  --bg-snake-body: #606060;
  --bg-snake-head: #62ffb0;

  /* apple */
  --bg-apple: #fa5252;
  --bg-apple-moving: var(--bg-board);

  --apple-duration: 0.2s;
}

html {
  height: 100%;

  font-size: 0.5rem;
}

@media (min-width: 425px) {
  html {
    font-size: 0.5625rem;
  }
}

@media (min-width: 576px) {
  html {
    font-size: 0.625rem;
  }
}

@media (min-width: 768px) {
  html {
    font-size: 0.6875rem;
  }
}

@media (min-width: 992px) {
  html {
    font-size: 0.75rem;
  }
}

@media (min-width: 1200px) {
  html {
    font-size: 0.8125rem;
  }
}

@media (min-width: 1400px) {
  html {
    font-size: 0.875rem;
  }
}

@media (min-width: 1920px) {
  html {
    font-size: 0.9375rem;
  }
}

body {
  height: 100%;
  background-color: var(--bg);
  color: var(--fg);

  font-size: 1.4rem;
}

/* header */
header.header {
  height: var(--sz-header-height);
}

.header__container {
  background-color: var(--bg-header);
  box-shadow: 0 0 1rem 0.2rem var(--bg-header-shadow);

  height: 100%;
  margin: 0 auto;
  max-width: 192rem;
  padding: 1rem 2rem;
  display: flex;
  gap: 1rem;
}

.header__status {
  flex: 1;

  display: flex;
  align-items: center;
  justify-content: space-between;
  text-transform: capitalize;
  gap: 5rem;
}

.header__status span {
  color: var(--fg-number);
}

.status__spacer {
  min-width: 3rem;
}

.navbar-toggle {
  cursor: pointer;
  padding: 1rem 0.5rem;
  display: grid;
  place-items: center;
}

.navbar-toggle .toggle-icon {
  position: relative;
  display: inline-block;

  width: 2rem;
  height: 0.3rem;
  border-radius: 0.1rem;
  background-color: var(--bg-navbar-toggle);
  transition: all 0.5s;
}

.navbar-toggle .toggle-icon::after,
.navbar-toggle .toggle-icon::before {
  content: '';
  position: absolute;

  width: 2rem;
  height: 0.3rem;
  border-radius: 0.1rem;
  background-color: var(--bg-navbar-toggle);
  transition: all 0.5s;
}

.navbar-toggle .toggle-icon::before {
  top: -0.6rem;
}

.navbar-toggle .toggle-icon::after {
  top: 0.6rem;
}

.navbar-toggle.active .toggle-icon {
  background-color: transparent;
}

.navbar-toggle.active .toggle-icon::before {
  -webkit-transform: translateY(6px) rotateZ(-45deg);
  transform: translateY(6px) rotateZ(-45deg);
}

.navbar-toggle.active .toggle-icon::after {
  -webkit-transform: translateY(-6px) rotateZ(45deg);
  transform: translateY(-6px) rotateZ(45deg);
}

.screen-overlay {
  z-index: 1;
  background-color: rgba(0, 0, 0, 0.4);
  transition: all 0.5s;
  visibility: hidden;
  opacity: 0;
  position: fixed;
  left: 0;
  top: 65px;
  bottom: 0;
  right: 0;
  cursor: pointer;
}

/* main */
main.snake-game {
  height: calc(100% - var(--sz-header-height));
  overflow: hidden;
}

main.snake-game .container {
  height: 100%;
  margin: 0 auto;
  max-width: 192rem;

  display: grid;
  place-items: center;
}

main.snake-game .board {
  position: relative;
  background-color: var(--bg-board);
  outline: 0.5rem solid var(--bg-board-outline);

  border-radius: 0.1rem;
}

/* blocks */
/* snake body, snake apple */
.board .snake-head,
.board .snake-body,
.board .apple {
  position: absolute;
  background-color: var(--bg-snake-body);

  border-radius: 0.1rem;
  aspect-ratio: 1;
}

/* snake head */
.board .snake-head {
  background-color: var(--bg-snake-head);
  box-shadow: 0 0 0.3em var(--bg-snake-head);
  z-index: 2;
}

/* snake apple */
.board .apple {
  background-color: var(--bg-apple);
  box-shadow: 0 0 0.3em var(--bg-apple);
  transition: all var(--apple-duration);
  z-index: 1;
}

.board .apple.hide {
  opacity: 0;
  visibility: 0;
}