:root {
  --bg-start: #e5eddc;
  --bg-end: #b9d3e3;
  --panel: rgba(251, 254, 248, 0.9);
  --ink: #15212f;
  --ink-soft: #435463;
  --accent: #2f6f66;
  --accent-deep: #255850;
  --line: rgba(21, 33, 47, 0.14);
  --board-shadow: 0 18px 45px rgba(0, 0, 0, 0.22);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Candara", "Trebuchet MS", "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 9% 11%, rgba(255, 255, 255, 0.7), transparent 36%),
    radial-gradient(circle at 90% 4%, rgba(47, 111, 102, 0.24), transparent 33%),
    linear-gradient(150deg, var(--bg-start), var(--bg-end));
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 18px;
  overscroll-behavior-y: contain;
}

#app {
  position: relative;
  width: min(1080px, 100%);
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.8);
  border-radius: 14px;
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.18);
  padding: 16px 16px 22px;
  overflow: hidden;
  touch-action: manipulation;
}

.titlebar {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: flex-start;
  padding: 4px 2px 8px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 12px;
}

.menu-btn {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  border: none;
  background: #163046;
  color: #fff;
  font-size: 1.2rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

.menu-btn:hover {
  filter: brightness(1.1);
}

h1 {
  font-size: 1.25rem;
  margin: 0;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.title-spacer {
  margin-left: auto;
  color: var(--ink-soft);
  font-weight: 700;
}

.controls {
  display: flex;
  gap: 8px;
  align-items: center;
  flex-wrap: wrap;
}

button {
  border: none;
  border-radius: 999px;
  background: linear-gradient(120deg, var(--accent), var(--accent-deep));
  color: white;
  padding: 9px 14px;
  font-weight: 700;
  cursor: pointer;
  transition:
    transform 130ms ease,
    filter 130ms ease;
}

button:hover {
  transform: translateY(-1px);
  filter: brightness(1.06);
}

#status {
  font-weight: 700;
  min-height: 1.4em;
  color: var(--ink-soft);
}

#playfield {
  position: relative;
  width: 100%;
  height: 74vh;
  min-height: 560px;
  border-radius: 12px;
  overflow: hidden;
  touch-action: none;
  background:
    radial-gradient(
      circle at 16% 10%,
      rgba(255, 255, 255, 0.5),
      transparent 40%
    ),
    repeating-linear-gradient(
      45deg,
      rgba(0, 0, 0, 0.025),
      rgba(0, 0, 0, 0.025) 9px,
      rgba(255, 255, 255, 0.05) 9px,
      rgba(255, 255, 255, 0.05) 18px
    ),
    #d4dfcd;
  border: 1px solid rgba(0, 0, 0, 0.08);
}

#board {
  position: absolute;
  border: 2px solid #0f1d2c;
  box-shadow: var(--board-shadow);
  background-color: rgba(255, 255, 255, 0.72);
  background-repeat: no-repeat;
  background-size: 100% 100%;
}

#board-overlay {
  position: absolute;
  pointer-events: none;
  user-select: none;
  background-repeat: no-repeat;
  background-size: 100% 100%;
  opacity: 0.2;
}

.piece {
  position: absolute;
  cursor: grab;
  touch-action: none;
  user-select: none;
  filter: drop-shadow(0 5px 8px rgba(0, 0, 0, 0.3));
}

.piece.dragging {
  cursor: grabbing;
  filter: drop-shadow(0 12px 14px rgba(0, 0, 0, 0.38));
}

.sidenav-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.28);
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
  z-index: 10000;
}

.sidenav-backdrop.open {
  opacity: 1;
  pointer-events: auto;
}

.sidenav {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: min(320px, 84vw);
  background: linear-gradient(180deg, #193247, #132434);
  color: #f4fcff;
  padding: 14px;
  transform: translateX(-104%);
  transition: transform 200ms ease;
  z-index: 10010;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.sidenav.open {
  transform: translateX(0);
}

.sidenav-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.sidenav-close {
  border: none;
  background: transparent;
  color: #f4fcff;
  cursor: pointer;
  font-size: 1.35rem;
}

.nav-item {
  width: 100%;
  border: none;
  border-radius: 10px;
  text-align: left;
  padding: 10px 12px;
  background: rgba(255, 255, 255, 0.1);
  color: #f4fcff;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
}

.nav-item:hover {
  background: rgba(255, 255, 255, 0.18);
}

.nav-icon {
  display: inline-block;
  width: 1.3rem;
}

.overlay-root {
  position: absolute;
  inset: 0;
  background: rgba(6, 15, 24, 0.45);
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 14px;
  z-index: 10020;
}

.overlay-root[hidden] {
  display: none;
}

.overlay-panel {
  width: min(640px, 100%);
  max-height: 84vh;
  overflow: auto;
  background: #f9fcff;
  border-radius: 14px;
  border: 1px solid rgba(23, 36, 52, 0.2);
  box-shadow: 0 18px 36px rgba(0, 0, 0, 0.24);
  padding: 14px;
  position: relative;
  z-index: 10030;
}

.overlay-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  border-bottom: 1px solid var(--line);
  padding-bottom: 8px;
  margin-bottom: 10px;
}

.overlay-head h2 {
  margin: 0;
  font-size: 1.1rem;
}

.overlay-page {
  display: none;
  line-height: 1.5;
}

.overlay-page.active {
  display: block;
}

.option-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(120px, 1fr));
  gap: 12px;
  margin-bottom: 12px;
}

.option-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.option-field select {
  padding: 8px;
  border-radius: 8px;
  border: 1px solid #9fb2c0;
  font-size: 1rem;
}

.palette-legend {
  margin: 8px 0 14px;
}

.palette-title {
  margin: 0 0 8px;
  font-weight: 700;
  color: var(--ink-soft);
}

.palette-swatches {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(24px, 1fr));
  gap: 6px;
}

.palette-swatch {
  height: 20px;
  border-radius: 6px;
  border: 1px solid rgba(0, 0, 0, 0.15);
}

@media (max-width: 700px) {
  #playfield {
    min-height: 650px;
    height: 82vh;
  }

  .controls {
    margin-top: 4px;
  }

  .title-spacer {
    display: none;
  }

  .option-grid {
    grid-template-columns: 1fr;
  }
}