/* Reset box-sizing for consisten sizing */
*,
*::after,
*::before {
  box-sizing: border-box;
}

/* Root variables for board size and mark size */
:root {
  --cell-size: min(26vw, 100px); /* 26% of viewport width or max 100px */
  --mark-size: calc(var(--cell-size) * 0.85); /* size of X and O marks */
}

/* Body styling for centering game */
body {
  margin: 0;
  height: 100svh; /* full viewport height including mobile */
  display: flex;
  justify-content: center;
  align-items: center;
}

/* Cover page styling */
.cover-page {
  position: fixed;
  inset: 0;
  background: linear-gradient(135deg, #111, #1f1f2f);
  color: white;
  display: grid;
  place-items: center;
  text-align: center;
  font-family: sans-serif;
}

/* Cover page title and description */
.cover-page h1 {
  font-size: 4rem;
  margin: 0;
  text-shadow: 2px 2px 6px rgba(255, 255, 255, 0.7);
}

/* Buttons in cover page */
.cover-page p {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: 2px;
  color: white;
  text-shadow: 2px 2px 6px rgba(255, 255, 255, 0.5);
}

.cover-page .mode-buttons {
  display: flex;
  gap: 20px;
  justify-content: center;
}

.cover-page .mode-buttons button {
  font-size: 1.5rem;
  padding: 10px 20px;
  margin: 10px;
  cursor: pointer;
  background-color: crimson;
  border: none;
  color: white;
  border-radius: 8px;
  transition: all 0.2 ease;
}

.cover-page .mode-buttons button:hover {
  transform: scale(1.05);
  box-shadow: 0 0 12px crimson;
}

/* Game container styling */
.game-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

.game-container,
.difficulty-page {
  display: none;
}

/* Difficulty page styling */
.difficulty-page {
  position: fixed;
  inset: 0;
  background-color: #111;
  color: white;
  display: none;
  place-items: center;
  text-align: center;
  font-family: sans-serif;
  text-shadow: 2px 2px 6px rgba(255, 255, 255, 0.5);
}

.difficulty-page h2 {
  font-size: 3rem;
  margin-bottom: 30px;
}

button[data-difficulty] {
  padding: 14px 32px;
  border: none;
  border-radius: 10px;
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  color: white;
  transition: transform 0.2 ease, background-color 0.2s ease,
    box-shadow 0.2s ease;
}

button[data-difficulty="easy"] {
  background-color: #22c55e;
}

button[data-difficulty="medium"] {
  background-color: #ea7908;
}

button[data-difficulty="hard"] {
  background-color: #7f1d1d;
}

button[data-difficulty]:hover {
  transform: scale(1.07);
  box-shadow: 0 0 15px rgba(255, 255, 255, 0.3);
}

button[data-difficulty]:active {
  transform: scale(0.97);
}
.difficulty-buttons {
  display: flex;
  gap: 20px;
  justify-content: center;
}

/* Top bar styling */
.top-bar {
  display: flex;
  justify-content: space-between;
  width: 100%;
  max-width: 360px;
  align-items: center;
  padding: 12px 20px;
  background-color: #222;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
  font-family: "Segoe UI", sans-serif;
}

.score {
  background-color: #111;
  padding: 8px 16px;
  border-radius: 8px;
  font-weight: bold;
  font-size: 1.1rem;
  color: white;
  display: flex;
  gap: 20px;
  box-shadow: inset 0 0 5px rgba(255, 255, 255, 0.2);
}

.score span {
  color: #22c55e; /* X score green */
  font-weight: bold;
  text-shadow: 0 0 4px rgba(255, 255, 255, 0.3);
}

.score span + span {
  color: #f87171; /* O score red */
}

/* Back button */
#backToMenu {
  padding: 8px 16px;
  background-color: crimson;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-weight: bold;
  transition: all 0.2s ease;
}

#backToMenu:hover {
  background-color: white;
  color: crimson;
  border: 1px solid crimson;
}

/* Turn indicator styling */
.turn-indicator {
  display: flex;
  justify-content: space-between;
  margin: 20px auto;
  border-radius: 12px;
  width: 220px;
  background-color: #222;
  padding: 8px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
  font-family: "Segoe UI", sans-serif;
}

.turn {
  flex: 1;
  padding: 10px 0;
  text-align: center;
  font-size: 1.8rem;
  font-weight: bold;
  background-color: #111;
  color: white;
  border-radius: 8px;
  transition: all 0.2s ease;
  cursor: default;
  box-shadow: inset 0 0 5px rgba(255, 255, 255, 0.1);
}

.turn.active {
  background-color: crimson;
  color: white;
  box-shadow: 0 0 15px rgba(255, 255, 255, 0.5);
  transform: scale(1.05);
}

/* Board styling */
.board {
  display: grid;
  grid-template-columns: repeat(3, auto);
}

.cell {
  width: var(--cell-size);
  height: var(--cell-size);
  border: 1px solid black;
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  cursor: pointer;
}

.cell:first-child,
.cell:nth-child(2),
.cell:nth-child(3) {
  border-top: none;
}

.cell:nth-child(3n + 1) {
  border-left: none;
}

.cell:nth-child(3n + 3) {
  border-right: none;
}

.cell:last-child,
.cell:nth-child(8),
.cell:nth-child(7) {
  border-bottom: none;
}

.cell.x,
.cell.circle {
  cursor: not-allowed;
}

.cell.x::before,
.cell.x::after,
.cell.circle::before {
  background-color: black;
}

.board.x .cell:not(.x):not(.circle):hover::before,
.board.x .cell:not(.x):not(.circle):hover::after,
.board.circle .cell:not(.x):not(.circle):hover::before {
  background-color: lightgrey;
}

/* X marking styling*/
.cell.x::before,
.cell.x::after,
.board.x .cell:not(.x):not(.circle):hover::before,
.board.x .cell:not(.x):not(.circle):hover::after {
  content: "";
  position: absolute;
  width: calc(var(--mark-size) * 0.15);
  height: var(--mark-size);
}

.cell.x::before,
.board.x .cell:not(.x):not(.circle):hover::before {
  transform: rotate(45deg);
}

.cell.x::after,
.board.x .cell:not(.x):not(.circle):hover::after {
  transform: rotate(-45deg);
}

/* O mark styling */
.cell.circle::before,
.cell.circle::after,
.board.circle .cell:not(.x):not(.circle):hover::before,
.board.circle .cell:not(.x):not(.circle):hover::after {
  content: "";
  position: absolute;
  border-radius: 50%;
}

.cell.circle::before,
.board.circle .cell:not(.x):not(.circle):hover::before {
  width: var(--mark-size);
  height: var(--mark-size);
}

.cell.circle::after,
.board.circle .cell:not(.x):not(.circle):hover::after {
  width: calc(var(--mark-size) * 0.7);
  height: calc(var(--mark-size) * 0.7);
  background-color: white;
}

/* Winning message overlay */
.winning-message {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.9);
  color: white;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 20px;
}

.winning-message div[data-winning-message-text] {
  font-size: 3rem;
  margin-bottom: 30px;
  word-wrap: break-word;
  text-shadow: 2px 2px 6px rgba(255, 255, 255, 0.5);
}

.end-buttons {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-top: 30px;
}

.winning-message button {
  font-size: 1.5rem;
  padding: 10px 20px;
  min-width: 120px;
  border-radius: 8px;
  background-color: white;
  border: 1px solid black;
  color: black;
  cursor: pointer;
  transition: all 0.2 ease;
}

.winning-message button:hover {
  background-color: black;
  color: white;
  border-color: white;
}

.winning-message.show {
  display: flex;
}

/* Fallback for browsers not supporting 100svh */
@supports not (height: 100svh) {
  body {
    min-height: 100vh;
  }
}

.board {
  display: grid;
  grid-template-columns: repeat(3, var(--cell-size));
  grid-template-rows: repeat(3, var(--cell-size));
  gap: 5px;
}