:root {
  --bg: #f7f9fc;
  --panel: #ffffff;
  --text: #111827;
  --muted: #667085;
  --accent: #4f8cff;
  --accent-2: #50e3c2;
  --warning: #ffb020;
  --danger: #ff5a6b;
  --gap: 10px;
  --board-size: min(82vmin, 420px);
  --cell-radius: 8px;
  --cell-border: 2px;
  --shadow-sm: 0 6px 16px rgba(0,0,0,.12);
  --shadow-md: 0 10px 30px rgba(0,0,0,.18);
  --game-gap: 16px;
  --title-center-offset: 0px;
  --controls-center-offset: 0px;
  /* Tagline under logo */
  --tagline-size: 16px;
  --tagline-color: var(--muted);
  --tagline-offset-x: 0px;  /* horizontal shift relative to logo center */
  --tagline-offset-y: -4px;  /* vertical space between logo and text */
  /* Main page controls */
  --main-btn-height: 34px;      /* height of top buttons */
  --logo-buttons-gap: 36px;     /* space between logo block and buttons block */
}
* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, Noto Sans, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: url('color_sample.PNG') center / cover no-repeat fixed, var(--bg);
}
#app { min-height: 100%; display: grid; }
.screen { display: none; min-height: 100%; }
.screen.active { display: grid; }
#start-screen .center {
  margin: auto;
  text-align: center;
  padding: 24px;
}
#start-screen h1 { font-size: clamp(28px, 4vw, 48px); margin: 0 0 8px; }
.subtitle { color: var(--muted); margin: 6px 0 0; }
#howto-screen { grid-template-rows: auto 1fr; }
.screen-header { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 8px; padding: 12px 16px; }
.screen-header .left { justify-self: start; }
.screen-header .center { justify-self: center; }
.screen-header .right { justify-self: end; }
.title { margin: 0; font-size: clamp(18px, 2.2vw, 28px); color: var(--muted); margin-inline-end: var(--title-center-offset); display: inline-grid; width: max-content; justify-items: center; }
#howto-screen .content { max-width: 880px; margin: 0 auto; padding: 12px 20px 40px; }
.rules { line-height: 1.5; color: var(--muted); }
.rules li { margin: 10px 0; }
.top-bar { display: grid; justify-content: center; row-gap: 8px; padding: 12px 16px 0; }
.header-top { display: grid; grid-auto-flow: column; align-items: center; gap: var(--logo-buttons-gap, 16px); justify-content: center; }
.top-controls { display: grid; grid-auto-flow: column; gap: 8px; margin-inline-start: var(--controls-center-offset); }
.top-bar .subtitle { text-align: center; }
.top-controls .btn { background: #ffffff; color: var(--text); min-height: var(--main-btn-height, 44px); border: 1px solid rgba(0,0,0,0.08); }
.title .tagline { display: block; font-weight: 700; font-size: var(--tagline-size); color: var(--tagline-color); margin-top: var(--tagline-offset-y); transform: translateX(var(--tagline-offset-x)); }
#game-screen { grid-template-rows: auto 1fr; }
.game-wrap {
  display: grid;
  grid-template-columns: auto auto;
  gap: var(--game-gap);
  justify-content: center;
  align-items: start;
  padding: 18px 16px 24px;
}
.board-wrap { position: relative; display: grid; place-items: center; }
.board {
  width: var(--board-size);
  height: var(--board-size);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: var(--gap);
  background: linear-gradient(180deg, #ffffff, #f5f7fb);
  padding: var(--gap);
  border-radius: 14px;
  box-shadow: var(--shadow-md);
  position: relative;
  z-index: 1;
}
.cell {
  position: relative;
  border-radius: var(--cell-radius);
  background: rgba(0,0,0,0.03);
  outline: var(--cell-border) solid rgba(0,0,0,0.08);
  overflow: hidden;
  aspect-ratio: 1 / 1;
}
.cell.dropzone { transition: outline-color .2s, background-color .2s; }
.cell.dropzone.over { outline-color: rgba(0,0,0,0.1); background-color: rgba(0,0,0,0.04); }
.pieces-layer {
  position: absolute;
  width: var(--board-size);
  height: var(--board-size);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: var(--gap);
  padding: var(--gap);
  pointer-events: none;
  z-index: 2;
}
.piece {
  pointer-events: auto;
  user-select: none;
  -webkit-user-drag: element;
  display: grid;
  grid-template-columns: repeat(var(--cols, 5), 1fr);
  grid-template-rows: repeat(var(--rows, 1), 1fr);
  /* remove rectangular container look */
  border-radius: 0;
  color: #111315;
  font-weight: 900;
  letter-spacing: 1px;
  text-shadow: 0 1px 0 rgba(255,255,255,.4);
  cursor: grab;
  box-shadow: none; /* no rectangular shadow */
  transition: transform .12s ease-out, box-shadow .12s ease-out, opacity .12s ease-out;
  overflow: visible; /* keep holes and tile corners visible */
  background: transparent; /* ensure no white fill behind holes/corners */
}
.piece:active { cursor: grabbing; transform: translateY(1px); }
.piece.preview {
  pointer-events: none;
  opacity: 0.55;
  box-shadow: none;
  /* remove dashed rectangular outline around preview */
}
/* In the pool (right side), make sure holes and rounded corners are fully transparent */
.pool .piece { background: transparent; overflow: visible; }
.piece-cell { display: grid; place-items: center; border-radius: var(--cell-radius); }
.piece-cell .char { font-size: clamp(16px, 3.6vmin, 28px); }
.piece-hole { background: transparent; }
.pool {
  --pool-cell: 34px;
  --pool-gap: 6px;
  width: calc(5 * var(--pool-cell) + 4 * var(--pool-gap));
  display: grid;
  grid-auto-flow: dense;
  grid-auto-rows: var(--pool-cell);
  grid-auto-columns: var(--pool-cell);
  grid-template-columns: repeat(5, var(--pool-cell));
  gap: var(--pool-gap);
  background: transparent;
  border-radius: 0;
  padding: 0;
  box-shadow: none;
  overflow: visible;
}
.pool.dropzone.over { outline: 2px dashed rgba(79,140,255,0.6); }
.pool .piece {
  width: 100%;
  height: 100%;
  grid-column: span var(--cols);
  grid-row: span var(--rows);
}
.pool .piece-cell .char { font-size: 16px; }
.solution-overlay {
  position: absolute;
  width: var(--board-size);
  height: var(--board-size);
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
  gap: var(--gap);
  padding: var(--gap);
  pointer-events: none;
  opacity: 0;
  transition: opacity .18s ease-out;
  z-index: 3;
}
.solution-overlay.visible { opacity: .9; }
.solution-overlay .ghost {
  border-radius: var(--cell-radius);
  display: grid; place-items: center;
  color: rgba(0,0,0,0.35);
  font-weight: 800; font-size: clamp(18px, 5.3vmin, 42px);
  background: repeating-linear-gradient(135deg, rgba(0,0,0,0.06) 0 6px, transparent 6px 12px);
}
.side { display: grid; align-content: start; gap: 12px; }
.controls { display: grid; gap: 8px; background: var(--panel); padding: 12px; border-radius: 10px; box-shadow: var(--shadow-sm); border: 1px solid rgba(0,0,0,0.06); }
.pool-title { margin: 0 0 6px 0; color: var(--muted); font-weight: 600; }
.btn { appearance: none; border: 1px solid rgba(0,0,0,0.1); border-radius: 10px; padding: 10px 14px; color: var(--text); background: #ffffff; cursor: pointer; font-weight: 700; box-shadow: var(--shadow-sm); }
.btn:hover { filter: brightness(0.98); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: linear-gradient(180deg, var(--accent), #2d69ff); color: white; border-color: transparent; }
.btn.ghost { background: transparent; border: 1px solid rgba(0,0,0,0.2); color: var(--text); }
.btn-row { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }
.modal { position: fixed; inset: 0; display: grid; place-items: center; background: rgba(0,0,0,.35); opacity: 0; pointer-events: none; transition: opacity .15s; z-index: 9999; }
.modal.show { opacity: 1; pointer-events: auto; }
.modal-card { background: #ffffff; border: 1px solid rgba(0,0,0,0.12); border-radius: 14px; padding: 20px; min-width: 260px; max-width: 600px; max-height: 80vh; overflow: auto; box-shadow: var(--shadow-md); }
.modal-card h2 { margin: 0 0 6px; }
.modal-card p { color: var(--muted); margin: 0 0 16px; }
.modal-actions { margin-top: 12px; text-align: right; }
.share-panel { display: grid; gap: 14px; }
.share-preview-wrap { display: grid; place-items: center; }
.pattern-preview {
  --cell: 30px;
  --gap: 4px;
  display: grid;
  grid-template-columns: repeat(5, var(--cell));
  grid-template-rows: repeat(5, var(--cell));
  gap: var(--gap);
  padding: var(--gap);
  background: #ffffff;
  border-radius: 12px;
  box-shadow: inset 0 0 0 1px rgba(0,0,0,0.08);
}
.pattern-preview .sq { width: var(--cell); height: var(--cell); border-radius: 6px; box-shadow: inset 0 0 0 1px rgba(0,0,0,0.06); }
.actions.share-actions { display: flex; gap: 8px; flex-wrap: wrap; justify-content: center; }
.share-row { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 10px; }
.share-label { color: var(--text); font-weight: 700; }
.share-buttons {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 12px;
    }
    .share-buttons a {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 48px;
      height: 48px;
      border-radius: 50%;
      color: #fff;
      text-decoration: none;
      font-size: 22px;
      transition: opacity 0.2s;
    }
    .share-buttons a:hover {
      opacity: 0.8;
    }
    /* Button colors */
    .facebook   { background: #3b5998; }
    .twitter    { background: #000000; } /* X (Twitter) */
    .linkedin   { background: #0077b5; }
    .pinterest  { background: #bd081c; }
    .reddit     { background: #ff4500; }
    .whatsapp   { background: #25d366; }
    .telegram   { background: #0088cc; }
    .email      { background: #666666; }@media (max-width: 960px) {
  .game-wrap { grid-template-columns: 1fr; }
  .pattern-preview { --cell: 24px; --gap: 5px; }
}

@media (max-width: 768px) {
  html, body { overflow-x: hidden; }

  .game-wrap {
    grid-template-columns: 1fr;
    justify-items: center;
    align-items: start;
    gap: 14px;
  }

  .board-wrap,
  .board,
  .pieces-layer,
  .solution-overlay {
    width: min(92vw, var(--board-size));
    height: min(92vw, var(--board-size));
  }

  .pool {
    --pool-cell: clamp(26px, 8vw, 34px);
    --pool-gap: 6px;
    width: min(92vw, calc(5 * var(--pool-cell) + 4 * var(--pool-gap)));
    margin-top: 6px;
    justify-content: center;
  }

  .pool .piece-cell .char { font-size: clamp(14px, 3.5vmin, 16px); }
}

@media (max-width: 768px) {
  html, body { overflow-x: hidden; }
  .main { padding-left: 0; padding-right: 0; }

  .game-wrap {
    grid-template-columns: 1fr;
    justify-items: stretch;
    width: 100vw;
    margin: 0;
  }

  .board-wrap {
    width: 100vw;
    margin: 0;
    justify-self: stretch;
  }

  .board,
  .pieces-layer,
  .solution-overlay {
    box-sizing: border-box;
    width: calc(100vw - env(safe-area-inset-left) - env(safe-area-inset-right));
    height: calc(100vw - env(safe-area-inset-left) - env(safe-area-inset-right));
    max-width: 100vw;
    max-height: 100vw;
    margin: 0 auto;
  }

  .pool {
    width: calc(100vw - env(safe-area-inset-left) - env(safe-area-inset-right));
    max-width: 100vw;
    margin-inline: auto;
  }

  .topbar {
    padding-left: max(8px, env(safe-area-inset-left));
    padding-right: max(8px, env(safe-area-inset-right));
  }
}