:root {
  --bg-1: linear-gradient(180deg, #f7f8fb, #e7edf3);
  --card: #ffffff;
  --muted: #6b7280;
  --accent: #6b21a8; /* purple */
  --board-deep: #0b3b5c; /* deep teal for the board */
  --hole-shadow: rgba(0, 0, 0, 0.35);
  --player1: #ef4444; /* red */
  --player2: #2563eb; /* blue */
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: Roboto, system-ui, -apple-system, "Segoe UI", Helvetica, Arial;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  background: var(--bg-1);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

#wrapper {
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
  display: flex;
  gap: 20px;
  align-items: center; /* center children horizontally so header/footer align */
  justify-content: center;
  flex-direction: column;
}

.title {
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  padding: 10px 16px;
  border-radius: 10px;
  display: inline-block;
  box-shadow: 0 6px 18px rgba(99, 102, 241, 0.08), 0 2px 6px rgba(0, 0, 0, 0.06);
  letter-spacing: 0.4px;
}

.game_description {
  text-align: center;
  color: var(--muted);
  margin: 6px 0 12px;
  font-size: 15px;
}

#gameboard {
  margin: 0 auto;
  background: linear-gradient(180deg, #f8fafc, #eef2ff);
  padding: 18px;
  border-radius: 14px;
  box-shadow: 0 10px 30px rgba(2, 6, 23, 0.08);
  display: flex;
  flex-direction: column;
  align-items: center;
}

#game_info,
#next_player {
  color: var(--muted);
  font-size: 14px;
  margin: 6px 0;
}

#game_info {
  font-weight: 600;
  color: #111827;
}

#game_table {
  margin-top: 12px;
  border-collapse: collapse;
}

/* style the drop buttons (thead) */
thead td {
  padding: 6px;
}

.drop {
  min-width: 56px;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid rgba(15, 23, 42, 0.06);
  background: linear-gradient(180deg, #fff, #f3f4f6);
  color: #0f172a;
  font-weight: 600;
  cursor: pointer;
  transition: transform 150ms ease, box-shadow 150ms ease, background 120ms ease;
  box-shadow: 0 6px 14px rgba(2, 6, 23, 0.06);
}

.drop:hover:not(:disabled) {
  transform: translateY(-3px);
}

.drop:active:not(:disabled) {
  transform: translateY(-1px);
}

.drop:focus {
  outline: 3px solid rgba(99, 102, 241, 0.12);
  outline-offset: 2px;
}

.drop:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.drop.col-full {
  background: #f1f5f9;
}

/* board look: rounded rectangle with holes */
table#game_table {
  background: var(--board-deep);
  padding: 12px;
  border-radius: 12px;
}

tbody tr {
  height: 56px;
}

.board_square {
  width: 56px;
  height: 56px;
  padding: 0;
  margin: 4px;
  border-radius: 8px;
  box-shadow: inset 0 -6px 12px rgba(0, 0, 0, 0.25);
  background: radial-gradient(
      circle at 50% 30%,
      rgba(255, 255, 255, 0.02),
      transparent 25%
    ),
    linear-gradient(180deg, #0b3b5c, #06324d);
  text-align: center;
  display: flex; /* use flexbox to perfectly center pieces */
  align-items: center;
  justify-content: center;
}

.board_square .piece {
  display: inline-block;
  vertical-align: middle;
}

/* piece appearance */
.piece {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: inline-block;
  transition: transform 260ms cubic-bezier(0.2, 0.9, 0.3, 1),
    box-shadow 260ms ease;
  transform: none;
  box-shadow: 0 6px 18px rgba(2, 6, 23, 0.16);
  background: linear-gradient(180deg, #fff8, rgba(0, 0, 0, 0.08));
}

.player0 {
  background: #cbd5e1;
  box-shadow: none;
}

.player1 {
  background: radial-gradient(circle at 35% 30%, #fff6, var(--player1));
  padding: 2px 4px;
}

.player2 {
  background: radial-gradient(circle at 35% 30%, #fff6, var(--player2));
  padding: 2px 4px;
}

/* appear animation: when a piece is present we bring it down */
.board_square .piece {
  transform: translateY(0);
}

/* winning highlight */
.board_square.win {
  box-shadow: 0 0 28px 6px rgba(245, 158, 11, 0.12),
    inset 0 0 0 3px rgba(245, 158, 11, 0.06);
  transform: scale(1.02);
}

.board_square.win .piece {
  box-shadow: 0 6px 22px rgba(245, 158, 11, 0.18),
    0 1px 0 rgba(255, 255, 255, 0.04);
}

/* restart button */
#restart {
  margin-top: 8px;
  padding: 8px 12px;
  border-radius: 8px;
  border: none;
  color: #fff;
  background: linear-gradient(180deg, var(--accent), #4c1d95);
  box-shadow: 0 8px 26px rgba(99, 102, 241, 0.12);
  cursor: pointer;
  font-weight: 700;
}

#restart:hover {
  transform: translateY(-2px);
  opacity: 0.98;
}

/* responsive */
@media (max-width: 600px) {
  .board_square {
    width: 44px;
    height: 44px;
  }
  .piece {
    width: 30px;
    height: 30px;
  }
  .drop {
    min-width: 44px;
    padding: 6px 8px;
  }
  #wrapper {
    padding: 10px;
  }
}

/* grid layout for the board */
.grid-board {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
}

.grid-top {
  display: flex;
  gap: 8px;
  margin-bottom: 8px;
}

/* the actual board grid: use --cols set on the element to create columns */
.grid {
  display: grid;
  grid-template-columns: repeat(var(--cols), 56px);
  grid-auto-rows: 56px;
  gap: 8px;
  justify-content: center; /* center grid in container */
  align-items: center;
}

.drop {
  min-width: 56px;
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid rgba(15, 23, 42, 0.06);
  background: linear-gradient(180deg, #fff, #f3f4f6);
  color: #0f172a;
  font-weight: 600;
  cursor: pointer;
  transition: transform 150ms ease, box-shadow 150ms ease, background 120ms ease;
  box-shadow: 0 6px 14px rgba(2, 6, 23, 0.06);
}
.drop.focused {
  box-shadow: 0 8px 18px rgba(59, 130, 246, 0.18);
  transform: translateY(-4px);
}

/* toolbar and footer */
.toolbar {
  display: flex;
  gap: 8px;
  align-items: center;
  margin: 10px 0;
}

.toolbar button {
  padding: 6px 10px;
  border-radius: 8px;
  border: none;
  background: #111827;
  color: #fff;
}

.toolbar label {
  color: var(--muted);
  font-size: 13px;
}

.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.toggle span {
  color: var(--muted);
}

.site-header .controls {
  display: flex;
  gap: 12px;
  align-items: center;
}

.toggle {
  display: flex;
  align-items: center;
  gap: 6px;
}

.site-footer {
  color: var(--muted);
  font-size: 12px;
  margin-top: 12px;
  text-align: center;
  width: 100%;
}

/* theme: dark mode */
:root[data-theme="dark"] {
  --bg-1: linear-gradient(180deg, #0f1724, #071024);
  --card: #071023;
  --muted: #9ca3af;
  --accent: #8b5cf6;
  --board-deep: #071e2b;
}

/* scoreboard */
#scoreboard {
  font-weight: 700;
  color: var(--muted);
  font-size: 14px;
}