:root {
  --font-display: "Ma Shan Zheng", "Noto Serif SC", serif;
  --font-ui: "Source Serif 4", "Noto Serif SC", Georgia, serif;
  --font-piece: "Noto Serif SC", "Source Han Serif SC", "Songti SC", serif;

  --radius-sm: 8px;
  --radius-md: 18px;
  --transition: 220ms ease;

  color-scheme: light;
  --bg-0: #f6efe6;
  --bg-1: #e9d8c2;
  --bg-2: #d4bd9f;
  --ink: #2a1f16;
  --ink-muted: #6d5643;
  --panel: rgba(255, 249, 240, 0.78);
  --panel-border: rgba(90, 60, 30, 0.14);
  --accent: #8b3a2a;
  --accent-soft: rgba(139, 58, 42, 0.12);
  --toggle-bg: rgba(43, 33, 24, 0.08);
  --toggle-border: rgba(43, 33, 24, 0.12);

  /* Polished rosewood / maple palette */
  --wood-face: #c9a06a;
  --wood-face-mid: #b88852;
  --wood-face-deep: #9a6a3a;
  --wood-warm: #e8c896;
  --wood-cool: #8a5a32;
  --wood-highlight: rgba(255, 240, 210, 0.55);
  --wood-grain: rgba(70, 35, 12, 0.14);
  --line: rgba(42, 22, 10, 0.82);
  --line-soft: rgba(42, 22, 10, 0.5);
  --river-ink: rgba(62, 36, 18, 0.72);
  --frame-outer: #3a2112;
  --frame-mid: #6b3f22;
  --frame-light: #a06a3c;
  --frame-shine: rgba(255, 220, 175, 0.28);

  --piece-red-rim: #8a2418;
  --piece-red-ink: #9c1c12;
  --piece-black-rim: #241c14;
  --piece-black-ink: #17120d;
  --piece-shadow: rgba(28, 14, 6, 0.42);
  --piece-contact: rgba(40, 18, 6, 0.28);
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg-0: #14100d;
  --bg-1: #221910;
  --bg-2: #342314;
  --ink: #f4ead9;
  --ink-muted: #c4ad92;
  --panel: rgba(24, 17, 12, 0.82);
  --panel-border: rgba(230, 200, 160, 0.1);
  --accent: #d77a5a;
  --accent-soft: rgba(215, 122, 90, 0.14);
  --toggle-bg: rgba(243, 231, 213, 0.08);
  --toggle-border: rgba(243, 231, 213, 0.12);

  --wood-face: #a07448;
  --wood-face-mid: #865532;
  --wood-face-deep: #6a4022;
  --wood-warm: #c49a62;
  --wood-cool: #5a3218;
  --wood-highlight: rgba(255, 220, 170, 0.2);
  --wood-grain: rgba(12, 6, 2, 0.28);
  --line: rgba(18, 10, 5, 0.88);
  --line-soft: rgba(12, 6, 2, 0.7);
  --river-ink: rgba(18, 10, 5, 0.78);
  --frame-outer: #140c08;
  --frame-mid: #3d2312;
  --frame-light: #6e4424;
  --frame-shine: rgba(255, 210, 150, 0.14);

  --piece-red-rim: #6e1c12;
  --piece-red-ink: #8a160e;
  --piece-black-rim: #14100c;
  --piece-black-ink: #0c0a08;
  --piece-shadow: rgba(0, 0, 0, 0.55);
  --piece-contact: rgba(0, 0, 0, 0.4);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  font-family: var(--font-ui);
  color: var(--ink);
  background:
    radial-gradient(1100px 640px at 18% -8%, var(--wood-highlight), transparent 55%),
    radial-gradient(900px 560px at 92% 8%, var(--accent-soft), transparent 52%),
    linear-gradient(165deg, var(--bg-0), var(--bg-1) 46%, var(--bg-2));
  background-attachment: fixed;
}

.wood-defs {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}

.app {
  height: 100dvh;
  min-height: 100dvh;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  overflow: hidden;
}

.topbar {
  position: relative;
  z-index: 80;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--panel-border);
  background: var(--panel);
  backdrop-filter: blur(14px);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-mark {
  width: 2.75rem;
  height: 2.75rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  font-family: var(--font-display);
  font-size: 1.55rem;
  color: var(--piece-red-ink);
  background:
    radial-gradient(circle at 30% 26%, rgba(255, 245, 220, 0.85), transparent 40%),
    radial-gradient(circle at 70% 78%, rgba(60, 25, 10, 0.35), transparent 48%),
    linear-gradient(150deg, #f0d4ae, #c89458);
  border: 3px solid var(--piece-red-rim);
  box-shadow:
    inset 0 1px 0 rgba(255, 245, 220, 0.7),
    0 8px 18px var(--piece-shadow);
}

.brand-text h1 {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.7rem, 3vw, 2.2rem);
  font-weight: 400;
  letter-spacing: 0.04em;
  line-height: 1;
}

.brand-text p {
  margin: 0.15rem 0 0;
  color: var(--ink-muted);
  font-size: 0.85rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 0.55rem;
}

.lang-select {
  position: relative;
  display: grid;
  place-items: center;
}

.lang-select-btn {
  position: relative;
  appearance: none;
  height: 2.75rem;
  min-width: 4.4rem;
  padding: 0 1.7rem 0 0.8rem;
  border-radius: 999px;
  border: 1px solid var(--toggle-border);
  background: var(--toggle-bg);
  color: var(--ink);
  font: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  cursor: pointer;
  transition:
    background var(--transition),
    border-color var(--transition),
    transform var(--transition);
}

.lang-select-btn::after {
  content: "";
  position: absolute;
  right: 0.7rem;
  top: 50%;
  width: 0.45rem;
  height: 0.45rem;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: translateY(-70%) rotate(45deg);
  opacity: 0.7;
  pointer-events: none;
}

.lang-select-btn:hover {
  transform: translateY(-1px);
  background: var(--accent-soft);
}

.lang-select-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.lang-menu {
  position: absolute;
  top: calc(100% + 0.35rem);
  right: 0;
  z-index: 90;
  margin: 0;
  padding: 0.35rem;
  list-style: none;
  min-width: 6.5rem;
  border-radius: 12px;
  border: 1px solid var(--panel-border);
  background: var(--bg-0);
  color: var(--ink);
  box-shadow: 0 14px 30px rgba(20, 10, 4, 0.22);
}

.lang-menu[hidden] {
  display: none;
}

.lang-menu li {
  padding: 0.45rem 0.7rem;
  border-radius: 8px;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  cursor: pointer;
  color: var(--ink);
}

.lang-menu li:hover,
.lang-menu li:focus-visible {
  outline: none;
  background: var(--accent-soft);
}

.lang-menu li[aria-selected="true"] {
  background: var(--accent-soft);
  color: var(--accent);
}

.theme-toggle {
  position: relative;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: 999px;
  border: 1px solid var(--toggle-border);
  background: var(--toggle-bg);
  color: var(--ink);
  cursor: pointer;
  display: grid;
  place-items: center;
  transition:
    background var(--transition),
    border-color var(--transition),
    transform var(--transition);
}

.theme-toggle:hover {
  transform: translateY(-1px);
  background: var(--accent-soft);
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.theme-icon {
  width: 1.25rem;
  height: 1.25rem;
  display: none;
}

.theme-icon svg {
  width: 100%;
  height: 100%;
}

html[data-theme="light"] .theme-icon-moon,
html[data-theme="dark"] .theme-icon-sun {
  display: block;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}