/* ==========================================================
   座標軍艦棋 — 深海夜戰風格 v4
   設計系統: Ocean navy + Cyan + Coral + Gold
   相容: 保留 app.js 所依賴的所有 class
   ========================================================== */

:root {
  --ocean-deep: #050d22;
  --ocean-900: #0a1740;
  --ocean-800: #11235a;
  --ocean-700: #1a3480;
  --ocean-600: #2550a8;
  --ocean-500: #3a6fd6;
  --ocean-400: #6b9eff;
  --ocean-300: #9cc2ff;

  --cyan: #00e0ff;
  --cyan-bright: #5af5ff;
  --cyan-dim: #0099b8;

  --coral: #ff5a6e;
  --coral-bright: #ff8294;
  --coral-deep: #c2283a;

  --gold: #ffc857;
  --gold-bright: #ffe08a;
  --gold-deep: #c89325;

  --lime: #9cff6b;
  --lime-deep: #5ac230;

  --violet: #b488ff;

  --cream: #f5ead3;
  --cream-dim: #d9cda8;

  --paper: #fef6e3;
  --paper-dim: #f0e3c0;

  --ink: #0b1733;
  --ink-dim: #2c3b64;
  --ink-mute: #627aa8;

  --white: #ffffff;

  --sans: "Noto Sans TC", -apple-system, BlinkMacSystemFont, "PingFang TC", "Microsoft JhengHei", sans-serif;
  --display: "M PLUS Rounded 1c", "Noto Sans TC", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --r-sm: 8px;
  --r-md: 14px;
  --r-lg: 22px;
  --r-xl: 32px;
  --r-pill: 999px;

  --shadow-sm: 0 2px 0 rgba(5, 13, 34, 0.35);
  --shadow-md: 0 6px 0 rgba(5, 13, 34, 0.35), 0 8px 24px rgba(5, 13, 34, 0.25);
  --shadow-lg: 0 10px 0 rgba(5, 13, 34, 0.4), 0 20px 40px rgba(5, 13, 34, 0.35);
  --shadow-paper: 0 2px 0 rgba(80, 60, 0, 0.15), 0 8px 20px rgba(80, 60, 0, 0.08);
}

* { box-sizing: border-box; }
html, body {
  margin: 0; padding: 0;
  min-height: 100%;
  background: var(--ocean-deep);
  color: var(--cream);
  font-family: var(--sans);
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  overflow-x: hidden;
}

/* ---------- 海洋背景 ---------- */
.ocean-bg {
  position: fixed; inset: 0;
  background:
    radial-gradient(ellipse 120% 80% at 50% -20%, rgba(90, 245, 255, 0.18), transparent 60%),
    radial-gradient(ellipse 80% 60% at 85% 110%, rgba(180, 136, 255, 0.22), transparent 60%),
    radial-gradient(ellipse 80% 60% at 15% 110%, rgba(0, 224, 255, 0.15), transparent 60%),
    linear-gradient(180deg, #050d22 0%, #0a1740 45%, #11235a 100%);
  z-index: -3;
  pointer-events: none;
}
.ocean-grid {
  position: fixed; inset: 0;
  background-image:
    linear-gradient(rgba(120, 180, 255, 0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(120, 180, 255, 0.06) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse 80% 70% at 50% 50%, black 40%, transparent 90%);
  -webkit-mask-image: radial-gradient(ellipse 80% 70% at 50% 50%, black 40%, transparent 90%);
  z-index: -2;
  pointer-events: none;
}
.ocean-stars {
  position: fixed; inset: 0;
  background-image:
    radial-gradient(1px 1px at 20% 30%, rgba(255,255,255,0.5), transparent 2px),
    radial-gradient(1px 1px at 80% 60%, rgba(255,255,255,0.4), transparent 2px),
    radial-gradient(1.5px 1.5px at 50% 85%, rgba(90,245,255,0.6), transparent 3px),
    radial-gradient(1px 1px at 15% 80%, rgba(255,255,255,0.4), transparent 2px),
    radial-gradient(1px 1px at 65% 15%, rgba(180, 136, 255, 0.6), transparent 2px),
    radial-gradient(1px 1px at 90% 40%, rgba(255,255,255,0.5), transparent 2px);
  z-index: -1;
  pointer-events: none;
  animation: twinkle 6s ease-in-out infinite alternate;
}
@keyframes twinkle {
  from { opacity: 0.5; }
  to { opacity: 1; }
}

/* ---------- 頂部 Topbar ---------- */
.app { position: relative; min-height: 100vh; display: flex; flex-direction: column; }
.topbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 18px 28px; gap: 16px;
  max-width: 1400px; width: 100%; margin: 0 auto;
}
.brand { display: flex; align-items: center; gap: 12px; cursor: pointer; user-select: none; }
.brand-mark {
  width: 44px; height: 44px; border-radius: 12px;
  background: linear-gradient(135deg, var(--cyan) 0%, var(--ocean-500) 100%);
  display: grid; place-items: center;
  box-shadow: 0 3px 0 rgba(0,0,0,0.4), inset 0 2px 0 rgba(255,255,255,0.3);
  font-size: 22px;
}
.brand-text { display: flex; flex-direction: column; line-height: 1; }
.brand-name { font-family: var(--display); font-weight: 900; font-size: 20px; color: var(--white); letter-spacing: 0.02em; }
.brand-sub { font-family: var(--mono); font-size: 10px; color: var(--cyan-bright); letter-spacing: 0.2em; margin-top: 3px; text-transform: uppercase; }
.topbar-actions { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }

/* ---------- Screen ---------- */
.screen {
  max-width: 1280px; width: 100%;
  margin: 0 auto;
  padding: 12px 28px 60px;
  animation: fadeIn 0.35s ease;
  position: relative;
  color: var(--cream);
}
.hidden { display: none !important; }
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

h1, h2, h3 { color: var(--white); margin-top: 0; font-family: var(--display); letter-spacing: 0.01em; font-weight: 900; }
h1 { font-size: clamp(28px, 4vw, 44px); line-height: 1.1; }
h2 { font-size: clamp(22px, 3vw, 32px); margin-bottom: 12px; }
h3 { font-size: 18px; color: var(--cyan-bright); margin-bottom: 10px; }

p { color: var(--ocean-300); line-height: 1.65; }
code {
  font-family: var(--mono);
  background: rgba(0, 224, 255, 0.08);
  color: var(--cyan-bright);
  padding: 2px 7px;
  border-radius: 6px;
  font-size: 0.88em;
  border: 1px solid rgba(0, 224, 255, 0.15);
}
b, strong { color: var(--white); }
ol, ul { line-height: 1.8; color: var(--cream); }

/* ---------- 按鈕(預設:深海主按鈕) ---------- */
button {
  font: inherit;
  font-family: var(--display);
  font-weight: 800;
  letter-spacing: 0.02em;
  border: none;
  cursor: pointer;
  padding: 12px 20px;
  border-radius: var(--r-md);
  background: linear-gradient(180deg, var(--cyan-bright) 0%, var(--cyan) 100%);
  color: var(--ocean-deep);
  box-shadow: 0 5px 0 var(--cyan-dim), 0 10px 20px rgba(0, 224, 255, 0.3);
  transition: transform 0.1s, filter 0.15s, box-shadow 0.1s;
  min-height: 44px;
  touch-action: manipulation;
  -webkit-appearance: none;
}
button:hover:not(:disabled) { filter: brightness(1.1); }
button:active:not(:disabled) { transform: translateY(3px); box-shadow: 0 2px 0 var(--cyan-dim); }
button:disabled { opacity: 0.4; cursor: not-allowed; transform: none !important; filter: grayscale(0.4); }

button.secondary {
  background: linear-gradient(180deg, var(--ocean-500) 0%, var(--ocean-600) 100%);
  color: var(--white);
  box-shadow: 0 5px 0 var(--ocean-800), 0 10px 20px rgba(37, 80, 168, 0.3);
}
button.secondary:active:not(:disabled) { box-shadow: 0 2px 0 var(--ocean-800); }

button.danger {
  background: linear-gradient(180deg, var(--coral-bright) 0%, var(--coral) 100%);
  color: var(--white);
  box-shadow: 0 5px 0 var(--coral-deep), 0 10px 20px rgba(255, 90, 110, 0.3);
}
button.danger:active:not(:disabled) { box-shadow: 0 2px 0 var(--coral-deep); }

button.gold {
  background: linear-gradient(180deg, var(--gold-bright) 0%, var(--gold) 100%);
  color: var(--ocean-deep);
  box-shadow: 0 5px 0 var(--gold-deep), 0 10px 20px rgba(255, 200, 87, 0.3);
}
button.gold:active:not(:disabled) { box-shadow: 0 2px 0 var(--gold-deep); }

button.ghost {
  background: transparent;
  color: var(--cream);
  border: 2px solid rgba(156, 194, 255, 0.35);
  box-shadow: 0 3px 0 rgba(5, 13, 34, 0.5);
}
button.ghost:hover:not(:disabled) { background: rgba(156, 194, 255, 0.1); }
button.ghost:active:not(:disabled) { box-shadow: 0 1px 0 rgba(5, 13, 34, 0.5); }

button.nav-btn {
  padding: 10px 16px;
  border-radius: var(--r-pill);
  font-size: 13px;
  background: rgba(255,255,255,0.06);
  color: var(--cream);
  border: 1px solid rgba(156, 194, 255, 0.2);
  box-shadow: none;
  font-weight: 700;
  min-height: 38px;
}
button.nav-btn:hover:not(:disabled) { background: rgba(255,255,255,0.12); transform: translateY(-1px); filter: none; }
button.nav-btn:active:not(:disabled) { transform: translateY(0); box-shadow: none; }

button.btn-lg { padding: 18px 30px; font-size: 17px; }
button.btn-sm { padding: 8px 14px; font-size: 13px; min-height: 36px; }

.orient-btn { padding: 10px 14px !important; font-size: 0.92em; min-height: 40px; }

/* ---------- 輸入框 ---------- */
input[type="text"], input[type="number"] {
  font: inherit;
  padding: 12px 14px;
  border: 2px solid rgba(156, 194, 255, 0.2);
  border-radius: var(--r-md);
  width: 100%;
  max-width: 280px;
  min-height: 44px;
  background: rgba(5, 13, 34, 0.6);
  color: var(--white);
  font-weight: 600;
  transition: border-color 0.15s, box-shadow 0.15s;
  -webkit-appearance: none;
}
input[type="text"]:focus, input[type="number"]:focus {
  outline: none;
  border-color: var(--cyan-bright);
  box-shadow: 0 0 0 3px rgba(0, 224, 255, 0.2);
}
input[type="text"]::placeholder, input[type="number"]::placeholder { color: var(--ink-mute); }

/* ---------- 版面輔助 ---------- */
.row { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; margin: 12px 0; }
label { display: inline-flex; align-items: center; gap: 8px; font-weight: 500; color: var(--cream); }

.tag {
  display: inline-block;
  background: rgba(0, 224, 255, 0.12);
  color: var(--cyan-bright);
  padding: 5px 12px;
  border-radius: var(--r-pill);
  font-size: 0.85em;
  font-weight: 700;
  font-family: var(--mono);
  letter-spacing: 0.08em;
  border: 1px solid rgba(0, 224, 255, 0.25);
}

.notice {
  background: rgba(0, 224, 255, 0.08);
  border-left: 3px solid var(--cyan);
  padding: 12px 14px;
  border-radius: var(--r-md);
  margin: 12px 0;
  font-size: 0.92em;
  color: var(--cream);
}
.notice code { background: rgba(0,0,0,0.25); }

.error {
  background: rgba(255, 90, 110, 0.12);
  border-left: 3px solid var(--coral);
  padding: 12px 14px;
  border-radius: var(--r-md);
  margin: 12px 0;
  font-size: 0.92em;
  color: var(--coral-bright);
}
.success {
  background: rgba(156, 255, 107, 0.1);
  border-left: 3px solid var(--lime);
  padding: 12px 14px;
  border-radius: var(--r-md);
  margin: 12px 0;
  font-size: 0.95em;
  color: var(--lime);
}

/* ---------- 首頁 Hero ---------- */
.hero {
  text-align: center;
  padding: 30px 0 20px;
  position: relative;
}
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 6px 14px;
  border-radius: var(--r-pill);
  background: rgba(0, 224, 255, 0.12);
  border: 1px solid rgba(0, 224, 255, 0.3);
  font-family: var(--mono);
  font-size: 11px;
  color: var(--cyan-bright);
  letter-spacing: 0.2em;
  margin-bottom: 20px;
  text-transform: uppercase;
}
.hero-title {
  font-family: var(--display);
  font-weight: 900;
  font-size: clamp(40px, 7vw, 84px);
  line-height: 0.95;
  color: var(--white);
  margin: 0 0 10px;
  text-shadow:
    0 2px 0 var(--ocean-800),
    0 4px 0 var(--ocean-900),
    0 10px 40px rgba(0, 224, 255, 0.4);
  letter-spacing: -0.02em;
}
.hero-title .accent { color: var(--cyan-bright); }
.hero-sub {
  font-size: 17px;
  color: var(--ocean-300);
  margin: 10px 0 0;
  font-weight: 500;
}
.hero-chips {
  display: flex; flex-wrap: wrap; gap: 8px; justify-content: center;
  margin-top: 22px;
}
.chip {
  padding: 8px 14px;
  border-radius: var(--r-pill);
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(156, 194, 255, 0.2);
  font-size: 13px;
  font-weight: 600;
  color: var(--cream);
  display: inline-flex; align-items: center; gap: 6px;
}
.chip-icon { color: var(--cyan-bright); }

/* ---------- CTA 卡片(建房 / 加入 / 批量) ---------- */
.cta-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(220px, 340px));
  gap: 20px;
  width: 100%;
  max-width: 720px;
  margin: 30px auto 0;
  justify-content: center;
}
.cta-card {
  background: linear-gradient(180deg, rgba(26, 52, 128, 0.7) 0%, rgba(10, 23, 64, 0.9) 100%);
  border: 2px solid rgba(156, 194, 255, 0.2);
  border-radius: var(--r-lg);
  padding: 24px 22px 22px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
  text-align: left;
  color: inherit;
  box-shadow: none;
  min-height: 180px;
  font-family: inherit;
  font-weight: inherit;
  letter-spacing: normal;
  width: 100%;
}
.cta-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 100% 0%, var(--glow, rgba(0, 224, 255, 0.25)) 0%, transparent 60%);
  opacity: 0.6;
  pointer-events: none;
}
.cta-card:hover:not(:disabled) {
  transform: translateY(-4px);
  border-color: var(--glow-border, rgba(0, 224, 255, 0.5));
  box-shadow: 0 14px 40px rgba(0, 0, 0, 0.35), 0 0 0 1px var(--glow-border, rgba(0, 224, 255, 0.5));
  filter: none;
}
.cta-card:active:not(:disabled) { transform: translateY(-1px); box-shadow: 0 6px 20px rgba(0,0,0,0.3); }
.cta-card .cta-icon {
  font-size: 32px;
  width: 56px; height: 56px;
  display: grid; place-items: center;
  border-radius: 16px;
  background: var(--icon-bg, linear-gradient(135deg, var(--cyan) 0%, var(--ocean-500) 100%));
  box-shadow: 0 3px 0 rgba(0,0,0,0.4), inset 0 2px 0 rgba(255,255,255,0.3);
  margin-bottom: 16px;
}
.cta-card h3 {
  font-family: var(--display);
  font-weight: 900;
  font-size: 22px;
  color: var(--white);
  margin: 0 0 6px;
}
.cta-card p {
  margin: 0;
  font-size: 13px;
  color: var(--ocean-300);
  line-height: 1.5;
}
.cta-card .cta-arrow {
  position: absolute;
  right: 22px; bottom: 22px;
  font-size: 20px;
  color: var(--cyan-bright);
  transition: transform 0.2s;
}
.cta-card:hover .cta-arrow { transform: translateX(6px); }

/* CTA 色調變體 */
.cta-card.glow-gold { --glow: rgba(255, 200, 87, 0.3); --glow-border: rgba(255, 200, 87, 0.6); --icon-bg: linear-gradient(135deg, var(--gold-bright), var(--gold-deep)); }
.cta-card.glow-coral { --glow: rgba(255, 90, 110, 0.3); --glow-border: rgba(255, 90, 110, 0.55); --icon-bg: linear-gradient(135deg, var(--coral-bright), var(--coral-deep)); }
.cta-card.glow-violet { --glow: rgba(180, 136, 255, 0.3); --glow-border: rgba(180, 136, 255, 0.55); --icon-bg: linear-gradient(135deg, var(--violet), var(--ocean-600)); }

/* 老師工具列 */
.teacher-strip {
  display: flex; gap: 10px; flex-wrap: wrap; align-items: center;
  margin: 32px auto 0;
  max-width: 960px;
  padding: 14px 18px;
  background: rgba(255, 200, 87, 0.08);
  border: 1px dashed rgba(255, 200, 87, 0.3);
  border-radius: var(--r-lg);
}
.teacher-strip .label {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--gold-bright);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin-right: 6px;
}

/* ---------- 規則區:紙卷風格 ---------- */
.rules-section {
  width: 100%;
  max-width: 1100px;
  margin: 40px auto 0;
}
.rules-paper {
  background:
    repeating-linear-gradient(180deg, transparent 0 30px, rgba(120, 90, 30, 0.06) 30px 31px),
    linear-gradient(180deg, var(--paper) 0%, var(--paper-dim) 100%);
  color: var(--ink);
  border-radius: var(--r-lg);
  padding: 20px 26px;
  box-shadow: var(--shadow-paper), inset 0 0 40px rgba(130, 90, 30, 0.1);
  position: relative;
}
.rules-title {
  font-family: var(--display);
  font-weight: 900;
  font-size: 20px;
  color: var(--ocean-900);
  margin: 0 0 12px;
  display: flex; align-items: center; gap: 10px;
}
.rules-title-dot { width: 12px; height: 12px; border-radius: 50%; background: var(--coral); }
.rules-paper ol { padding-left: 0; margin: 0; list-style: none; counter-reset: rule; }
.rules-paper ol > li {
  position: relative;
  padding: 7px 0 7px 32px;
  border-top: 1px dashed rgba(80, 60, 0, 0.18);
  counter-increment: rule;
  color: var(--ink);
  font-size: 13.5px;
  line-height: 1.6;
}
.rules-paper ol > li:first-of-type { border-top: none; padding-top: 0; }
.rules-paper ol > li:first-of-type::before { top: 0; }
.rules-paper ol > li::before {
  content: counter(rule);
  position: absolute;
  left: 0;
  top: 7px;
  font-family: var(--display);
  font-weight: 900;
  font-size: 17px;
  color: var(--coral-deep);
  line-height: 1.3;
  width: 24px;
}
.rules-paper b { color: var(--coral-deep); font-weight: 800; }
.rules-paper code {
  font-family: var(--mono);
  background: rgba(0,0,0,0.06);
  color: var(--ink);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 12.5px;
  border: none;
}
.rules-paper ul { margin: 4px 0 0; padding-left: 0; list-style: none; }
.rules-paper ul li {
  padding: 3px 0 3px 18px;
  position: relative;
  font-size: 13px;
  border: none !important;
  display: block !important;
  line-height: 1.6;
}
.rules-paper ul li::before {
  content: "▸";
  position: absolute; left: 4px; top: 3px;
  color: var(--ocean-600);
  font-weight: 700;
  font-size: 13px;
  font-family: var(--mono);
}
.rules-paper .tag {
  display: inline-flex; align-items: center; gap: 4px;
  background: #fff3d1;
  border: 1px solid var(--gold-deep);
  color: var(--coral-deep);
  padding: 1px 7px;
  border-radius: 5px;
  font-size: 11.5px;
  font-weight: 700;
  font-family: var(--mono);
  margin: 0 4px;
  vertical-align: middle;
}
.rules-paper small { color: var(--ink-dim); font-size: 12px; margin-left: 4px; }

/* ---------- 房號 / QR ---------- */
#qrBox {
  text-align: center;
  padding: 16px;
  background: #fff;
  border: 3px solid var(--cyan-bright);
  border-radius: var(--r-lg);
  display: inline-block;
  box-shadow: 0 10px 30px rgba(0, 224, 255, 0.2);
}
#roomCodeBig {
  font-size: 3em;
  font-weight: 900;
  letter-spacing: 10px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  text-shadow: 0 2px 0 var(--ocean-800), 0 4px 20px rgba(0, 224, 255, 0.5);
}

/* ---------- Trophy 獎盃 ---------- */
.trophy-img {
  display: block;
  width: 160px; height: auto;
  margin: 0 auto 14px;
  animation: trophy-pop 0.6s ease-out;
  filter: drop-shadow(0 10px 30px rgba(255, 200, 87, 0.4));
}
@keyframes trophy-pop {
  0% { transform: scale(0.4) rotate(-10deg); opacity: 0; }
  60% { transform: scale(1.1) rotate(4deg); opacity: 1; }
  100% { transform: scale(1) rotate(0); opacity: 1; }
}

/* ---------- 放船船艦選單 ---------- */
.ship-palette {
  display: flex; flex-direction: column; gap: 10px; flex-wrap: wrap;
  margin: 10px 0;
  padding: 14px;
  background: linear-gradient(180deg, rgba(26, 52, 128, 0.5) 0%, rgba(10, 23, 64, 0.7) 100%);
  border: 2px solid rgba(156, 194, 255, 0.2);
  border-radius: var(--r-lg);
  min-width: 260px;
}
.ship-item {
  padding: 10px 14px;
  border: 2px solid rgba(156, 194, 255, 0.15);
  border-radius: var(--r-md);
  cursor: pointer;
  background: rgba(5, 13, 34, 0.5);
  color: var(--cream);
  font-weight: 700;
  font-family: var(--display);
  transition: all 0.15s;
  min-height: 50px;
  display: inline-flex;
  align-items: center;
  gap: 10px;
  touch-action: manipulation;
  box-shadow: none;
}
.ship-item:hover:not(.placed) {
  background: rgba(0, 224, 255, 0.08);
  border-color: rgba(0, 224, 255, 0.4);
}
.ship-item.selected {
  background: rgba(0, 224, 255, 0.15);
  border-color: var(--cyan-bright);
  box-shadow: 0 0 0 3px rgba(0, 224, 255, 0.2);
  color: var(--white);
}
.ship-item.placed {
  opacity: 0.45;
  text-decoration: line-through;
  cursor: not-allowed;
  background: rgba(5, 13, 34, 0.3);
}
.ship-icon {
  height: 28px;
  width: auto;
  max-width: 80px;
  object-fit: contain;
  vertical-align: middle;
}
.ship-item.selected .ship-icon { filter: brightness(1.3) drop-shadow(0 0 6px var(--cyan-bright)); }

/* ---------- 棋盤容器 ---------- */
.board-wrapper {
  display: flex; gap: 24px; flex-wrap: wrap; justify-content: center;
  margin: 18px 0;
}
.board-block {
  text-align: center;
  background: linear-gradient(180deg, rgba(10, 23, 64, 0.9) 0%, rgba(5, 13, 34, 0.95) 100%);
  border: 2px solid rgba(156, 194, 255, 0.2);
  border-radius: var(--r-lg);
  padding: 18px;
  box-shadow: inset 0 0 60px rgba(0, 224, 255, 0.08), 0 10px 30px rgba(0,0,0,0.3);
  max-width: 100%;
  flex: 1 1 380px;
  position: relative;
}
.board-block::before {
  content: "";
  position: absolute;
  inset: 10px;
  background: radial-gradient(circle at 50% 50%, rgba(0, 224, 255, 0.05) 0%, transparent 60%);
  pointer-events: none;
  border-radius: calc(var(--r-lg) - 8px);
}
.board-block h3 {
  margin: 0 0 12px;
  font-size: 14px;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  display: flex; justify-content: center; align-items: center; gap: 6px;
  position: relative; z-index: 1;
}
.board { display: inline-block; position: relative; max-width: 100%; width: 100%; z-index: 1; }
.board-svg {
  background: transparent;
  display: block;
  width: 100%;
  height: auto;
  max-width: 460px;
  margin: 0 auto;
}
.board-legend {
  font-size: 12px;
  color: var(--ocean-300);
  margin-top: 10px;
  padding: 8px 10px;
  background: rgba(5, 13, 34, 0.5);
  border-radius: var(--r-md);
  line-height: 1.6;
  border: 1px solid rgba(156, 194, 255, 0.1);
}

/* ---------- HUD 統計卡 ---------- */
.hud {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 12px;
  margin: 16px 0;
}
.hud-cell {
  text-align: center;
  background: linear-gradient(180deg, rgba(26, 52, 128, 0.5) 0%, rgba(10, 23, 64, 0.7) 100%);
  border: 1px solid rgba(156, 194, 255, 0.2);
  padding: 14px 8px;
  border-radius: var(--r-md);
  transition: transform 0.2s, box-shadow 0.2s;
}
.hud-cell:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(0, 224, 255, 0.15); border-color: rgba(0, 224, 255, 0.4); }
.hud-cell small {
  display: block;
  color: var(--ocean-300);
  font-family: var(--mono);
  font-size: 10px;
  margin-bottom: 6px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
.hud-cell strong {
  font-size: 1.8em;
  color: var(--gold-bright);
  font-family: var(--display);
  font-weight: 900;
  display: block;
  line-height: 1;
}

/* ---------- 回合指示 ---------- */
.turn-indicator {
  padding: 14px 22px;
  border-radius: var(--r-pill);
  text-align: center;
  font-weight: 800;
  font-size: 1.1em;
  margin: 14px auto;
  max-width: 480px;
  transition: all 0.3s;
  background: rgba(5, 13, 34, 0.5);
  border: 2px solid rgba(156, 194, 255, 0.2);
  color: var(--ocean-300);
  font-family: var(--display);
}
.turn-mine {
  background: linear-gradient(180deg, rgba(0, 224, 255, 0.2), rgba(0, 224, 255, 0.1));
  border-color: var(--cyan-bright);
  color: var(--white);
  box-shadow: 0 0 0 3px rgba(0, 224, 255, 0.2), 0 0 40px rgba(0, 224, 255, 0.3);
  animation: turn-pulse 1.8s ease-in-out infinite;
}
@keyframes turn-pulse {
  0%, 100% { box-shadow: 0 0 0 3px rgba(0, 224, 255, 0.2), 0 0 40px rgba(0, 224, 255, 0.3); }
  50% { box-shadow: 0 0 0 5px rgba(0, 224, 255, 0.3), 0 0 60px rgba(0, 224, 255, 0.5); }
}
.turn-opponent {
  background: rgba(5, 13, 34, 0.5);
  border-color: rgba(180, 136, 255, 0.3);
  color: var(--ocean-300);
}

/* ---------- 攻擊模式切換 ---------- */
.attack-modes {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin: 14px 0;
  background: rgba(5, 13, 34, 0.5);
  padding: 6px;
  border-radius: var(--r-md);
  border: 1px solid rgba(156, 194, 255, 0.15);
}
.attack-modes button {
  padding: 12px;
  border-radius: 10px;
  font-family: var(--display);
  font-weight: 800;
  font-size: 14px;
  background: transparent;
  color: var(--ocean-300);
  box-shadow: none;
  min-height: 44px;
}
.attack-modes button:hover:not(:disabled) { background: rgba(255,255,255,0.06); filter: none; }
.attack-modes button:active:not(:disabled) { transform: none; }
.mode-active {
  background: linear-gradient(180deg, var(--cyan-bright) 0%, var(--cyan) 100%) !important;
  color: var(--ocean-deep) !important;
  box-shadow: 0 2px 0 var(--cyan-dim), 0 4px 12px rgba(0, 224, 255, 0.4) !important;
}

/* 攻擊輸入區 */
#attackCoordBox, #attackEqBox {
  background: rgba(5, 13, 34, 0.6);
  padding: 16px;
  border-radius: var(--r-md);
  margin: 10px 0;
  border: 2px solid rgba(156, 194, 255, 0.2);
}

/* ---------- 紀錄表 ---------- */
table.log {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88em;
  margin: 10px 0;
  background: rgba(5, 13, 34, 0.5);
  border-radius: var(--r-md);
  overflow: hidden;
  border: 1px solid rgba(156, 194, 255, 0.15);
}
table.log th, table.log td {
  padding: 10px 12px;
  border-bottom: 1px solid rgba(156, 194, 255, 0.1);
  text-align: left;
  color: var(--cream);
}
table.log th {
  background: rgba(0, 224, 255, 0.08);
  font-weight: 700;
  color: var(--cyan-bright);
  font-family: var(--mono);
  font-size: 0.82em;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}
table.log tr.hit { background: rgba(255, 200, 87, 0.08); }
table.log tr.hit td { color: var(--gold-bright); }
table.log tr.sunk { background: rgba(255, 90, 110, 0.1); font-weight: 700; }
table.log tr.sunk td { color: var(--coral-bright); }
table.log a { color: var(--cyan-bright); text-decoration: none; }
table.log a:hover { text-decoration: underline; }

table.leaderboard tr.top1 { background: linear-gradient(90deg, rgba(255, 200, 87, 0.18) 0%, rgba(255, 200, 87, 0.05) 100%); font-weight: bold; }
table.leaderboard tr.top1 td:first-child { color: var(--gold-bright); }
table.leaderboard tr.top2 { background: linear-gradient(90deg, rgba(180, 180, 200, 0.12) 0%, transparent 100%); }
table.leaderboard tr.top2 td:first-child { color: #d4d4e0; }
table.leaderboard tr.top3 { background: linear-gradient(90deg, rgba(220, 140, 90, 0.15) 0%, transparent 100%); }
table.leaderboard tr.top3 td:first-child { color: #d8a57a; }
table.leaderboard small { color: var(--ink-mute); font-weight: normal; display: block; font-size: 0.74em; }

/* ---------- QR 牆 ---------- */
.qr-wall {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 14px; margin: 14px 0;
}
.qr-card {
  background: #fff;
  border: 2px solid var(--cyan-bright);
  border-radius: var(--r-lg);
  padding: 14px;
  text-align: center;
  page-break-inside: avoid;
  box-shadow: 0 8px 24px rgba(0, 224, 255, 0.15);
  color: var(--ocean-deep);
}
.qr-code-num {
  font-family: var(--mono);
  font-size: 1.9em;
  font-weight: 900;
  color: var(--ocean-900);
  letter-spacing: 5px;
  margin-bottom: 6px;
}
.qr-canvas, .qr-canvas-slot {
  min-height: 140px; display: flex; justify-content: center; align-items: center;
}
.qr-url { font-size: 0.7em; color: var(--ink-mute); word-break: break-all; margin-top: 4px; font-family: var(--mono); }

/* ---------- 列表頁操作按鈕 ---------- */
table.log button {
  padding: 6px 10px;
  font-size: 12px;
  min-height: 32px;
  border-radius: var(--r-sm);
  box-shadow: none;
  margin: 2px;
}
table.log button:active { transform: none; }

/* ---------- 響應式 ---------- */
@media (max-width: 980px) {
  .cta-grid { grid-template-columns: 1fr; }
  .topbar { padding: 14px 16px; }
}

@media (max-width: 900px) {
  .screen { padding: 10px 16px 40px; }
  h1 { font-size: 1.65em; }
  h2 { font-size: 1.35em; }

  .hud { grid-template-columns: repeat(3, 1fr); gap: 10px; }
  .hud-cell { padding: 12px 6px; }
  .hud-cell strong { font-size: 1.45em; }

  .board-wrapper { flex-direction: column; align-items: stretch; gap: 14px; }
  .board-block { max-width: 100%; }
  .board-svg { max-width: 100%; }

  .attack-modes { grid-template-columns: 1fr; }
}

@media (max-width: 600px) {
  .topbar { padding: 12px; }
  .brand-mark { width: 38px; height: 38px; font-size: 18px; }
  .brand-name { font-size: 16px; }
  .screen { padding: 8px 12px 36px; }
  h1 { font-size: 1.4em; }
  #roomCodeBig { font-size: 2.2em; letter-spacing: 6px; }

  .hud { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .hud-cell { padding: 10px 6px; }
  .hud-cell strong { font-size: 1.25em; }

  .hero { padding: 14px 0 8px; }

  .ship-palette { min-width: 0; }
  .ship-item { padding: 9px 12px; font-size: 0.92em; min-height: 44px; }

  .turn-indicator { font-size: 1em; padding: 12px 16px; }

  table.log { font-size: 0.78em; }
  table.log th, table.log td { padding: 6px 8px; }

  button { padding: 10px 14px; font-size: 14px; }
  button.btn-lg { padding: 14px 22px; font-size: 15px; }
}

/* ---------- 列印 ---------- */
@media print {
  body { background: #fff; padding: 0; color: #000; }
  .ocean-bg, .ocean-grid, .ocean-stars, .topbar { display: none !important; }
  .no-print { display: none !important; }
  .screen { box-shadow: none; max-width: 100%; border-radius: 0; padding: 0; }

  .qr-wall {
    display: block;
    grid-template-columns: none;
    gap: 0; margin: 0;
  }
  .qr-card {
    display: flex !important;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    width: 100%;
    min-height: 95vh;
    padding: 40px 20px;
    border: none;
    page-break-after: always;
    break-after: page;
    color: #000;
  }
  .qr-card:last-child { page-break-after: auto; break-after: auto; }
  .qr-code-num { font-size: 4em !important; letter-spacing: 12px; margin-bottom: 30px; color: #000 !important; }
  .qr-canvas-slot canvas { width: 400px !important; height: 400px !important; }
  .qr-url { font-size: 1em !important; margin-top: 24px; color: #333 !important; }
}

/* ==========================================================
   v5 新增:大廳 / 登入 / 等待 / 房間列表 / Tabs / iPad RWD
   ========================================================== */

/* NS 公開試玩徽章 */
.ns-badge {
  display: inline-block;
  padding: 4px 10px;
  border-radius: var(--r-pill);
  background: rgba(255, 200, 87, 0.18);
  color: var(--gold-bright);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.05em;
  border: 1px solid rgba(255, 200, 87, 0.4);
}

/* 首頁 QR 卡 */
.home-qr-card {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 20px 24px;
  margin: 20px auto 8px;
  max-width: 720px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(0, 224, 255, 0.18);
  border-radius: var(--r-lg);
  flex-wrap: wrap;
}
.home-qr-text { flex: 0 1 auto; min-width: 220px; max-width: 380px; }
.home-qr-title {
  font-size: 1.5em;
  font-weight: 800;
  color: var(--cyan-bright);
  margin-bottom: 8px;
  line-height: 1.2;
}
.home-qr-sub {
  font-size: 1.05em;
  color: var(--ocean-300);
  margin-bottom: 10px;
  line-height: 1.5;
}
.home-qr-url {
  font-family: var(--mono);
  font-size: 0.78em;
  color: var(--ocean-400);
  word-break: break-all;
}
.home-qr-canvas {
  flex: 0 0 auto;
  background: #fff;
  padding: 10px;
  border-radius: var(--r-md);
  line-height: 0;
}
.home-qr-canvas canvas { display: block; }

/* 卡片 */
.card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(0, 224, 255, 0.15);
  border-radius: var(--r-lg);
  padding: 18px 20px;
  margin: 14px 0;
}
.id-label {
  display: block;
  font-size: 0.95em;
  color: var(--ocean-300);
  margin-bottom: 8px;
}
.id-input {
  width: 100%;
  padding: 14px 16px;
  font-size: 1.2em;
  font-family: var(--mono);
  background: rgba(0, 0, 0, 0.25);
  color: var(--white);
  border: 2px solid rgba(0, 224, 255, 0.3);
  border-radius: var(--r-md);
  outline: none;
  letter-spacing: 0.06em;
}
.id-input:focus { border-color: var(--cyan); box-shadow: 0 0 0 3px rgba(0, 224, 255, 0.18); }
.hint {
  font-size: 0.85em;
  color: var(--ocean-300);
  margin: 8px 0 12px;
}
.hint code {
  background: rgba(0, 0, 0, 0.3);
  padding: 1px 5px;
  border-radius: 4px;
  font-family: var(--mono);
  color: var(--cyan-bright);
}

button.primary.big {
  font-size: 1.05em;
  padding: 14px 24px;
  min-height: 52px;
}
button.link {
  background: transparent;
  border: none;
  color: var(--ocean-300);
  text-decoration: underline;
  padding: 8px 4px;
  font-size: 0.95em;
  box-shadow: none;
  min-height: 36px;
}
button.link:hover { color: var(--cyan-bright); background: transparent; transform: none; }
button.link.small { font-size: 0.85em; padding: 4px 6px; }

/* 大廳 */
.lobby-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 12px 0;
}
.lobby-join-by-code {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  align-items: center;
  flex-wrap: wrap;
}
.lobby-join-by-code input {
  flex: 1;
  min-width: 120px;
  padding: 12px 14px;
  font-size: 1.1em;
  font-family: var(--mono);
  background: rgba(0, 0, 0, 0.25);
  color: var(--white);
  border: 2px solid rgba(0, 224, 255, 0.25);
  border-radius: var(--r-md);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}
.lobby-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
}
.lobby-header h3 { margin: 0; }
.room-count {
  font-size: 0.9em;
  color: var(--ocean-300);
}
.room-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.room-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 14px;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid rgba(0, 224, 255, 0.12);
  border-radius: var(--r-md);
  gap: 12px;
}
.room-info { flex: 1; min-width: 0; }
.room-code {
  font-family: var(--mono);
  font-size: 1.4em;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--cyan-bright);
}
.room-host {
  font-size: 0.85em;
  color: var(--ocean-300);
  margin-top: 2px;
}
.room-actions { flex: 0 0 auto; }
.mono { font-family: var(--mono); }

/* 等待對手畫面 */
.waiting-card {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 24px 20px;
}
.waiting-room-code .waiting-label {
  font-family: var(--mono);
  font-size: 0.85em;
  color: var(--cyan-bright);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin-bottom: 4px;
}
.big-code {
  font-family: var(--mono);
  font-size: 4em;
  font-weight: 900;
  letter-spacing: 0.18em;
  color: var(--cyan-bright);
  text-shadow: 0 0 24px rgba(0, 224, 255, 0.5);
  line-height: 1;
}
.waiting-qr-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
}
.waiting-qr {
  background: #fff;
  padding: 14px;
  border-radius: var(--r-md);
  line-height: 0;
}
.waiting-qr canvas { display: block; }
.waiting-qr-hint {
  font-size: 0.92em;
  color: var(--ocean-300);
  max-width: 360px;
  line-height: 1.55;
}
.loading-dots {
  font-size: 1em;
  color: var(--ocean-300);
}
.loading-dots span {
  display: inline-block;
  animation: bounce 1.2s infinite;
}
.loading-dots span:nth-child(2) { animation-delay: 0.15s; }
.loading-dots span:nth-child(3) { animation-delay: 0.3s; }
@keyframes bounce {
  0%, 100% { transform: translateY(0); opacity: 0.5; }
  50% { transform: translateY(-4px); opacity: 1; }
}

/* 排行榜 Tabs */
.tabs {
  display: flex;
  gap: 6px;
  margin: 14px 0 8px;
  flex-wrap: wrap;
}
.tabs .tab {
  padding: 10px 16px;
  border: 1px solid rgba(0, 224, 255, 0.2);
  background: rgba(255, 255, 255, 0.03);
  color: var(--ocean-300);
  border-radius: var(--r-pill);
  font-size: 0.95em;
  cursor: pointer;
  font-weight: 600;
  min-height: 40px;
  box-shadow: none;
}
.tabs .tab:hover { background: rgba(0, 224, 255, 0.08); transform: none; }
.tabs .tab.active {
  background: linear-gradient(135deg, var(--ocean-600), var(--ocean-500));
  color: var(--white);
  border-color: var(--cyan);
  box-shadow: 0 0 12px rgba(0, 224, 255, 0.25);
}
.loading {
  text-align: center;
  padding: 20px;
  color: var(--ocean-300);
}

/* ==========================================================
   iPad / 平板 / 觸控 RWD 強化
   ========================================================== */
@media (pointer: coarse) {
  button { min-height: 44px; }
  .id-input, .lobby-join-by-code input { min-height: 48px; }
  .room-row { padding: 14px 16px; }
  .room-code { font-size: 1.5em; }
  .board, .board-svg, button, .room-row, .cta-card { touch-action: manipulation; }
}

/* iPad Portrait */
@media (min-width: 700px) and (max-width: 1100px) and (orientation: portrait) {
  .screen { padding: 18px 22px 60px; max-width: 760px; margin: 0 auto; }
  .hud { grid-template-columns: repeat(5, 1fr); gap: 10px; }
  .hud-cell { padding: 12px 8px; }
  .hud-cell strong { font-size: 1.4em; }
  .board-wrapper { flex-direction: column; align-items: stretch; gap: 16px; }
  .board-block { max-width: 100%; }
  .board-svg { max-width: min(100%, 520px); height: auto; margin: 0 auto; display: block; }
  .home-qr-canvas canvas { width: 200px !important; height: 200px !important; }
  .big-code { font-size: 4.2em; }
  .waiting-qr canvas { width: 260px !important; height: 260px !important; }
  #attackCoordBox input, #attackEqBox input { min-height: 48px; font-size: 1.1em; }
}

/* iPad Landscape */
@media (min-width: 1000px) and (max-width: 1300px) and (orientation: landscape) {
  .screen { padding: 18px 28px 60px; max-width: 1180px; margin: 0 auto; }
  .board-wrapper { flex-direction: row; gap: 20px; align-items: flex-start; }
  .board-block { flex: 1; max-width: 50%; }
  .board-svg { max-width: 100%; height: auto; }
  .hud { grid-template-columns: repeat(5, 1fr); }
  .home-qr-canvas canvas { width: 200px !important; height: 200px !important; }
}

/* 手機 / 小平板 */
@media (max-width: 700px) {
  .home-qr-card { flex-direction: column; align-items: stretch; text-align: center; }
  .home-qr-canvas { align-self: center; }
  .home-qr-canvas canvas { width: 180px !important; height: 180px !important; }
  .big-code { font-size: 3em; letter-spacing: 0.12em; }
  .waiting-qr canvas { width: 220px !important; height: 220px !important; }
  .room-code { font-size: 1.3em; }
  .lobby-join-by-code { flex-direction: column; align-items: stretch; }
  .lobby-join-by-code input { width: 100%; }
}

/* 防止點擊棋盤觸發 iOS 文字選取 */
.board, .board-svg, .ship-palette, .room-list { user-select: none; -webkit-user-select: none; }