/* ===================================================================
   Unit 4 — shared interlocking puzzle (Smart CSS Puzzle)
   Pages set --u4-puzzle-stroke, --u4-puzzle-title-bg, --u4-puzzle-banner-bg.
   =================================================================== */

:root {
  --u4-puzzle-tab: 40px;
  --u4-puzzle-border: 5px;
}

.u4-puzzle {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: 100%;
  margin: 1.25rem 0 0;
  overflow: visible;
}

.u4-puzzle-banner {
  z-index: 2;
  display: inline-block;
  box-sizing: border-box;
  width: fit-content;
  max-width: min(100%, 42rem);
  margin: 0 auto 0.85rem;
  padding: 0.45rem 1.5rem;
  border: 0;
  border-radius: 10px;
  background: var(--u4-puzzle-banner-bg);
  color: var(--navy);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.6;
  letter-spacing: -0.02em;
  direction: rtl;
  text-align: right;
  text-wrap: pretty;
}

.u4-puzzle-board {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
  isolation: isolate;
  width: 100%;
  max-width: min(72rem, 100%);
  overflow: visible;
}

.u4-puzzle-row {
  display: flex;
  flex-direction: row;
  align-items: stretch;
  gap: 0;
  isolation: isolate;
  width: 100%;
  overflow: visible;
}

.u4-piece {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  flex: 1 1 0;
  min-width: 0;
  min-height: 12rem;
  overflow: visible;
  background: #ffffff;
  border: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  color: var(--navy);
}

.u4-piece + .u4-piece {
  margin-inline-start: calc(var(--u4-puzzle-border) * -1);
}

.u4-puzzle-row .u4-piece:nth-child(1) {
  z-index: 3;
}

.u4-puzzle-row .u4-piece:nth-child(2) {
  z-index: 2;
}

.u4-puzzle-row .u4-piece:nth-child(3) {
  z-index: 1;
}

.u4-piece-right,
.u4-puzzle-row .u4-piece:first-child {
  border-start-start-radius: 1.15rem;
  border-end-start-radius: 1.15rem;
  border-start-end-radius: 0.45rem;
  border-end-end-radius: 0.45rem;
}

.u4-piece-middle {
  border-radius: 0.45rem;
}

.u4-piece-left,
.u4-puzzle-row .u4-piece:last-child {
  border-start-start-radius: 0.45rem;
  border-end-start-radius: 0.45rem;
  border-start-end-radius: 1.15rem;
  border-end-end-radius: 1.15rem;
}

.u4-puzzle-row .u4-piece:only-child {
  border-radius: 1.15rem;
}

.u4-piece-surface {
  display: flex;
  flex: 1 1 auto;
  flex-direction: column;
  width: 100%;
  min-height: 12rem;
  background: transparent;
  border: 0;
}

.u4-piece:not(:last-child)::before {
  content: "";
  position: absolute;
  top: 50%;
  left: calc(-1 * var(--u4-puzzle-tab) + 2px);
  z-index: 4;
  box-sizing: border-box;
  width: var(--u4-puzzle-tab);
  height: var(--u4-puzzle-tab);
  background: #ffffff;
  border-top: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-left: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-bottom: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-right: 0;
  border-radius: 50%;
  transform: translateY(-50%);
  pointer-events: none;
}

.u4-piece:not(:last-child)::after {
  content: "";
  position: absolute;
  top: 50%;
  left: calc(-1 * var(--u4-puzzle-border));
  z-index: 5;
  width: calc(var(--u4-puzzle-border) + 8px);
  height: 26px;
  background: #ffffff;
  transform: translateY(-50%);
  pointer-events: none;
}

.u4-piece:last-child::before,
.u4-piece:last-child::after {
  content: none;
  display: none;
}

/* 2×2 boards: vertical tab from the top row down into the bottom row */
.u4-puzzle-board-2x2 {
  gap: 0;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child {
  z-index: 2;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:last-child {
  z-index: 1;
  margin-top: calc(var(--u4-puzzle-border) * -1);
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece:first-child {
  border-end-start-radius: 0;
  border-end-end-radius: 0.45rem;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece:last-child {
  border-end-start-radius: 0.45rem;
  border-end-end-radius: 0;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece-middle {
  border-end-start-radius: 0;
  border-end-end-radius: 0;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece:nth-child(2):nth-last-child(2) .u4-piece-surface::before,
.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece:nth-child(2):nth-last-child(2) .u4-piece-surface::after {
  content: none;
  display: none;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:last-child > .u4-piece:first-child {
  border-start-start-radius: 0;
  border-start-end-radius: 0.45rem;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:last-child > .u4-piece:last-child {
  border-start-start-radius: 0.45rem;
  border-start-end-radius: 0;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece .u4-piece-surface::before {
  content: "";
  position: absolute;
  left: 50%;
  bottom: calc(-1 * var(--u4-puzzle-tab) + 2px);
  z-index: 4;
  box-sizing: border-box;
  width: var(--u4-puzzle-tab);
  height: var(--u4-puzzle-tab);
  background: #ffffff;
  border-right: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-bottom: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-left: var(--u4-puzzle-border) solid var(--u4-puzzle-stroke);
  border-top: 0;
  border-radius: 50%;
  transform: translateX(-50%);
  pointer-events: none;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:first-child > .u4-piece .u4-piece-surface::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: calc(-1 * var(--u4-puzzle-border));
  z-index: 5;
  width: 26px;
  height: calc(var(--u4-puzzle-border) + 8px);
  background: #ffffff;
  transform: translateX(-50%);
  pointer-events: none;
}

.u4-puzzle-board-2x2 > .u4-puzzle-row:last-child .puzzle-content-safe-area {
  padding-top: calc(var(--u4-puzzle-tab) + 1.15rem);
}

.puzzle-content-safe-area {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: flex-start;
  box-sizing: border-box;
  width: 100%;
  height: 100%;
  direction: rtl;
  text-align: right;
}

.u4-piece:first-child .puzzle-content-safe-area {
  padding-top: 1.2rem;
  padding-right: 1.35rem;
  padding-bottom: 1.2rem;
  padding-left: 1.35rem;
}

.u4-piece:not(:first-child) .puzzle-content-safe-area {
  padding-top: 1.2rem;
  padding-right: calc(var(--u4-puzzle-tab) + 1.15rem);
  padding-bottom: 1.2rem;
  padding-left: 1.35rem;
}

.u4-cell-title {
  display: inline-block;
  align-self: flex-end;
  width: auto;
  max-width: 100%;
  margin-top: 0;
  margin-left: auto;
  margin-right: 0;
  margin-bottom: 0.55rem;
  padding: 0.25rem 0.875rem;
  border-radius: 8px;
  background: var(--u4-puzzle-title-bg);
  color: var(--navy);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.35;
  direction: rtl;
  text-align: right;
}

.u4-cell-text {
  width: 100%;
  max-width: none;
  margin: 0;
  color: var(--navy);
  font-size: 16px;
  font-weight: 400;
  line-height: 1.7;
  direction: rtl;
  text-align: right;
  text-wrap: pretty;
}

@media (max-width: 48rem) {
  .u4-puzzle-board,
  .u4-puzzle-row {
    flex-direction: column;
    gap: 0.9rem;
  }

  .u4-piece,
  .u4-piece-right,
  .u4-piece-middle,
  .u4-piece-left {
    z-index: 1;
    flex: 0 0 auto;
    height: auto;
    min-height: 0;
    margin: 0;
    border-radius: 1rem;
  }

  .u4-piece + .u4-piece {
    margin-inline-start: 0;
  }

  .u4-piece-surface {
    min-height: 0;
    height: auto;
    overflow: visible;
    border: 0;
    border-radius: 0;
  }

  .u4-piece::before,
  .u4-piece::after,
  .u4-piece-surface::before,
  .u4-piece-surface::after {
    display: none;
  }

  .u4-puzzle-board-2x2 {
    gap: 0.9rem;
  }

  .u4-puzzle-board-2x2 > .u4-puzzle-row:last-child {
    margin-top: 0;
  }

  .u4-puzzle-board-2x2 > .u4-puzzle-row:last-child .puzzle-content-safe-area {
    padding-top: 1.1rem;
  }

  .u4-piece .puzzle-content-safe-area,
  .u4-piece:first-child .puzzle-content-safe-area,
  .u4-piece:not(:first-child) .puzzle-content-safe-area {
    padding: 1.1rem 1.2rem;
  }
}

@media (max-width: 47.9375rem) {
  .u4-puzzle-banner {
    margin-bottom: 0.75rem;
    text-align: right;
  }
}