/* ==========================================================================
   base.css — giao diện dùng chung cho trang chủ và mọi game.
   Màu sắc khai báo bằng token trên :root; sáng/tối theo hệ điều hành, hoặc theo
   lựa chọn của người dùng (data-theme="light|dark" trên <html>, đặt bởi lang.js).
   ========================================================================== */

:root {
  --bg: #f6f7fb;
  --surface: #ffffff;
  --surface-2: #eff1f8;
  --text: #121830;
  --muted: #586079;
  --border: #e0e4ef;
  --accent: #0b56b8;
  --accent-strong: #094695;
  --accent-soft: #dce9fa;
  --on-accent: #ffffff;
  --good: #15803d;
  --good-soft: #dcfce7;
  --bad: #c02626;
  --bad-soft: #fee2e2;
  --warn: #b45309;
  --warn-soft: #fef3c7;
  --bit-on: #f59e0b;
  --bit-on-glow: rgb(245 158 11 / 0.45);
  --bit-off: #cfd5e3;
  --glow: rgb(11 86 184 / 0.16);
  --grid-line: rgb(18 24 48 / 0.05);
  --shadow: 0 1px 2px rgb(18 24 48 / 0.05), 0 8px 24px rgb(18 24 48 / 0.06);
  --shadow-lg: 0 2px 4px rgb(18 24 48 / 0.06), 0 18px 40px rgb(18 24 48 / 0.12);
  color-scheme: light;
  --radius: 16px;
  --radius-sm: 10px;
  --font: "Be Vietnam Pro", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", ui-monospace, "SFMono-Regular", Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #161c30;
    --surface: #1f2742;
    --surface-2: #29325a;
    --text: #f0f2fb;
    --muted: #b0b9d6;
    --border: #38426b;
    --accent: #6ea8f0;
    --accent-strong: #93bff5;
    --accent-soft: #223c66;
    --on-accent: #0b1020;
    --good: #4ade80;
    --good-soft: #12351f;
    --bad: #f87171;
    --bad-soft: #441b1d;
    --warn: #fbbf24;
    --warn-soft: #3d2f0e;
    --bit-on: #fbbf24;
    --bit-on-glow: rgb(251 191 36 / 0.4);
    --bit-off: #404b72;
    --glow: rgb(110 168 240 / 0.18);
    --grid-line: rgb(255 255 255 / 0.05);
    --shadow: 0 1px 2px rgb(0 0 0 / 0.35), 0 8px 24px rgb(0 0 0 / 0.3);
    --shadow-lg: 0 2px 4px rgb(0 0 0 / 0.4), 0 18px 40px rgb(0 0 0 / 0.45);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #161c30;
  --surface: #1f2742;
  --surface-2: #29325a;
  --text: #f0f2fb;
  --muted: #b0b9d6;
  --border: #38426b;
  --accent: #6ea8f0;
  --accent-strong: #93bff5;
  --accent-soft: #223c66;
  --on-accent: #0b1020;
  --good: #4ade80;
  --good-soft: #12351f;
  --bad: #f87171;
  --bad-soft: #441b1d;
  --warn: #fbbf24;
  --warn-soft: #3d2f0e;
  --bit-on: #fbbf24;
  --bit-on-glow: rgb(251 191 36 / 0.4);
  --bit-off: #404b72;
  --glow: rgb(110 168 240 / 0.18);
  --grid-line: rgb(255 255 255 / 0.05);
  --shadow: 0 1px 2px rgb(0 0 0 / 0.35), 0 8px 24px rgb(0 0 0 / 0.3);
  --shadow-lg: 0 2px 4px rgb(0 0 0 / 0.4), 0 18px 40px rgb(0 0 0 / 0.45);
  color-scheme: dark;
}
:root[data-theme="light"] { color-scheme: light; }

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

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.25s, color 0.25s;
}
::selection { background: var(--accent-soft); color: var(--text); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

h1, h2, h3 { line-height: 1.25; margin: 0 0 0.5em; }
h1 { font-size: clamp(1.6rem, 4vw, 2.2rem); font-weight: 800; letter-spacing: -0.02em; }
h2 { font-size: 1.3rem; font-weight: 700; letter-spacing: -0.01em; }
h3 { font-size: 1.05rem; font-weight: 700; }
p { margin: 0 0 0.8em; }
a { color: var(--accent); }
code, .mono, kbd { font-family: var(--mono); font-variant-ligatures: none; }
code { background: var(--surface-2); padding: 0.1em 0.35em; border-radius: 5px; font-size: 0.92em; }
sub { font-size: 0.7em; }
[hidden] { display: none !important; }

.container { width: 100%; max-width: 980px; margin: 0 auto; padding: 0 16px; }
.muted { color: var(--muted); }
.center { text-align: center; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.stack > * + * { margin-top: 12px; }
.spacer { flex: 1; }

/* ---------- Header chung (do common.js chèn vào) ---------- */
.site-header {
  position: sticky; top: 0; z-index: 20;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px) saturate(1.4);
  border-bottom: 1px solid var(--border);
}
.site-header .container { display: flex; align-items: center; gap: 8px; min-height: 60px; }
.site-header .back {
  text-decoration: none; color: var(--muted); font-weight: 600; font-size: 0.9rem; white-space: nowrap;
  padding: 6px 12px 6px 10px; border-radius: 999px; border: 1px solid var(--border); background: var(--surface);
  transition: color 0.15s, border-color 0.15s;
}
.site-header .back:hover { color: var(--accent); border-color: var(--accent); }
.site-header .title { font-weight: 800; font-size: 1.05rem; flex: 1; min-width: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; margin-left: 6px; letter-spacing: -0.01em; }
.site-header .title small { font-weight: 500; color: var(--muted); margin-left: 8px; font-size: 0.8rem; }

.icon-btn {
  width: 38px; height: 38px; border-radius: 12px; flex: none;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
  font: inherit; font-weight: 700; cursor: pointer; display: grid; place-items: center;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.icon-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }

/* ---------- Card, nút, badge ---------- */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 24px;
}

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 20px; border-radius: 12px; border: 1px solid transparent;
  background: var(--accent); color: var(--on-accent);
  font: inherit; font-weight: 700; cursor: pointer; text-decoration: none;
  transition: transform 0.08s, background 0.15s, box-shadow 0.15s, border-color 0.15s, color 0.15s;
  min-height: 42px;
}
.btn:hover { background: var(--accent-strong); box-shadow: 0 6px 18px var(--glow); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; box-shadow: none; }
.btn.ghost { background: var(--surface); color: var(--text); border-color: var(--border); box-shadow: none; }
.btn.ghost:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }
.btn.good { background: var(--good); color: var(--on-accent); }
.btn.bad { background: var(--bad); color: var(--on-accent); }
.btn.lg { padding: 14px 28px; font-size: 1.05rem; border-radius: 14px; }
.btn.sm { padding: 6px 12px; min-height: 34px; font-size: 0.88rem; border-radius: 10px; }

.badge {
  display: inline-block; padding: 2px 10px; border-radius: 999px;
  background: var(--accent-soft); color: var(--accent); font-size: 0.76rem; font-weight: 700; letter-spacing: 0.01em;
}
.badge.good { background: var(--good-soft); color: var(--good); }
.badge.warn { background: var(--warn-soft); color: var(--warn); }

kbd { font-family: var(--mono); font-variant-ligatures: none; }
code { background: var(--surface-2); padding: 0.1em 0.35em; border-radius: 5px; font-size: 0.92em; }
sub { font-size: 0.7em; }
[hidden] { display: none !important; }

.container { width: 100%; max-width: 980px; margin: 0 auto; padding: 0 16px; }
.muted { color: var(--muted); }
.center { text-align: center; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.stack > * + * { margin-top: 12px; }
.spacer { flex: 1; }

/* ---------- Header chung (do common.js chèn vào) ---------- */
.site-header {
  position: sticky; top: 0; z-index: 20;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(14px) saturate(1.4);
  border-bottom: 1px solid var(--border);
}
.site-header .container { display: flex; align-items: center; gap: 8px; min-height: 60px; }
.site-header .back {
  text-decoration: none; color: var(--muted); font-weight: 600; font-size: 0.9rem; white-space: nowrap;
  padding: 6px 12px 6px 10px; border-radius: 999px; border: 1px solid var(--border); background: var(--surface);
  transition: color 0.15s, border-color 0.15s;
}
.site-header .back:hover { color: var(--accent); border-color: var(--accent); }
.site-header .title { font-weight: 800; font-size: 1.05rem; flex: 1; min-width: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; margin-left: 6px; letter-spacing: -0.01em; }
.site-header .title small { font-weight: 500; color: var(--muted); margin-left: 8px; font-size: 0.8rem; }

.icon-btn {
  width: 38px; height: 38px; border-radius: 12px; flex: none;
  border: 1px solid var(--border); background: var(--surface); color: var(--text);
  font: inherit; font-weight: 700; cursor: pointer; display: grid; place-items: center;
  transition: border-color 0.15s, color 0.15s, background 0.15s;
}
.icon-btn:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }

/* ---------- Card, nút, badge ---------- */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px;
}

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 18px; border-radius: 999px; border: 1px solid transparent;
  background: var(--accent); color: var(--on-accent);
  font: inherit; font-weight: 700; cursor: pointer; text-decoration: none;
  transition: transform 0.08s, background 0.15s;
  min-height: 42px;
}
.btn:hover { background: var(--accent-strong); }
.btn:active { transform: translateY(1px); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn.ghost { background: transparent; color: var(--text); border-color: var(--border); }
.btn.ghost:hover { border-color: var(--accent); color: var(--accent); }
.btn.good { background: var(--good); color: var(--on-accent); }
.btn.bad { background: var(--bad); color: var(--on-accent); }
.btn.lg { padding: 14px 26px; font-size: 1.05rem; }
.btn.sm { padding: 6px 12px; min-height: 34px; font-size: 0.9rem; }

.badge {
  display: inline-block; padding: 2px 10px; border-radius: 999px;
  background: var(--accent-soft); color: var(--accent); font-size: 0.78rem; font-weight: 700;
}
.badge.good { background: var(--good-soft); color: var(--good); }
.badge.warn { background: var(--warn-soft); color: var(--warn); }

kbd {
  font-family: var(--mono); font-size: 0.8em; padding: 1px 6px; border-radius: 5px;
  border: 1px solid var(--border); border-bottom-width: 2px; background: var(--surface);
}

/* ---------- Bố cục trang game ---------- */
.game-main { padding-top: 24px; padding-bottom: 56px; }

.hud { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 14px; }
.hud .stat {
  background: var(--surface); border: 1px solid var(--border); border-radius: 10px;
  padding: 5px 14px; font-size: 0.88rem; font-weight: 600; color: var(--muted); box-shadow: var(--shadow);
}
.hud .stat b { font-family: var(--mono); color: var(--text); margin-left: 6px; }

.timer-bar { height: 6px; background: var(--surface-2); border-radius: 99px; overflow: hidden; margin-bottom: 16px; }
.timer-bar > span { display: block; height: 100%; background: var(--accent); width: 100%; transition: width 0.25s linear, background 0.3s; }
.timer-bar.low > span { background: var(--bad); }

.feedback {
  border-radius: var(--radius-sm); padding: 12px 16px; margin-top: 14px;
  background: var(--surface-2); min-height: 44px;
}
.feedback.good { background: var(--good-soft); color: var(--good); }
.feedback.bad { background: var(--bad-soft); color: var(--bad); }
.feedback.warn { background: var(--warn-soft); color: var(--warn); }
.feedback .detail { color: var(--text); font-weight: 400; display: block; margin-top: 4px; }

/* Màn hình bắt đầu: danh sách level */
.level-list { display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); margin-top: 20px; }
.level-btn {
  position: relative; text-align: left; padding: 16px 18px; border-radius: 14px;
  border: 1px solid var(--border); background: var(--surface-2); color: var(--text);
  font: inherit; cursor: pointer; display: flex; flex-direction: column; gap: 3px;
  transition: transform 0.12s, border-color 0.12s, box-shadow 0.12s, background 0.12s;
}
.level-btn:hover { transform: translateY(-2px); border-color: var(--accent); background: var(--surface); box-shadow: var(--shadow-lg); }
.level-btn .lv { font-family: var(--mono); font-size: 0.72rem; font-weight: 700; color: var(--accent); text-transform: uppercase; letter-spacing: 0.08em; }
.level-btn .nm { font-weight: 700; }
.level-btn .ds { font-size: 0.85rem; color: var(--muted); }
.level-btn .best { font-size: 0.78rem; color: var(--good); font-weight: 700; margin-top: 4px; }

.end-score { font-size: 3.4rem; font-weight: 800; color: var(--accent); font-family: var(--mono); line-height: 1.1; letter-spacing: -0.02em; }

/* ---------- Hàng bit dùng chung (G.bitRow) ---------- */
.bitrow { display: inline-flex; gap: 3px; }
.bitrow .bit {
  width: clamp(26px, 7.5vw, 38px); height: clamp(34px, 9vw, 44px); display: grid; place-items: center; padding: 0;
  font-family: var(--mono); font-weight: 700; font-size: clamp(1rem, 4vw, 1.35rem);
  border-radius: 7px; border: 2px solid var(--border); background: var(--surface-2); color: var(--text);
}
.bitrow .bit.one { background: var(--accent-soft); color: var(--accent); border-color: var(--accent); }
.bitrow button.bit { cursor: pointer; }
.bitrow button.bit:hover { border-color: var(--accent-strong); }
.bitrow .bit.mark { box-shadow: 0 0 0 3px var(--warn); }
.bitrow .bit.bad { border-color: var(--bad); background: var(--bad-soft); color: var(--bad); }
.bitrow.sm .bit { width: clamp(20px, 5.5vw, 28px); height: clamp(26px, 7vw, 32px); font-size: clamp(0.85rem, 3.2vw, 1.05rem); border-radius: 5px; }

/* ---------- Dialog hướng dẫn ---------- */
dialog.help {
  max-width: 560px; width: calc(100% - 32px); border: 1px solid var(--border);
  border-radius: var(--radius); background: var(--surface); color: var(--text);
  padding: 24px 26px; box-shadow: var(--shadow-lg);
}
dialog.help::backdrop { background: rgb(10 12 25 / 0.55); backdrop-filter: blur(3px); }
dialog.help ul { padding-left: 1.2em; }
dialog.help li { margin-bottom: 4px; }

/* ---------- Toast & confetti ---------- */
.toast-wrap { position: fixed; left: 50%; bottom: 24px; transform: translateX(-50%); z-index: 50; display: grid; gap: 8px; pointer-events: none; width: max-content; max-width: calc(100% - 32px); }
.toast {
  background: var(--text); color: var(--bg); padding: 10px 18px; border-radius: 12px;
  font-weight: 700; box-shadow: var(--shadow); animation: toast-in 0.2s ease-out; text-align: center;
}
.toast.good { background: var(--good); color: var(--on-accent); }
.toast.bad { background: var(--bad); color: var(--on-accent); }
@keyframes toast-in { from { transform: translateY(10px); opacity: 0; } }

.confetti { position: fixed; top: -12px; width: 9px; height: 14px; z-index: 60; pointer-events: none; border-radius: 2px; animation: confetti-fall linear forwards; }
@keyframes confetti-fall { to { transform: translate(var(--dx), 105vh) rotate(var(--rot)); } }

@keyframes shake { 20%, 60% { transform: translateX(-6px); } 40%, 80% { transform: translateX(6px); } }
.shake { animation: shake 0.35s; }
@keyframes pop { 0% { transform: scale(0.6); opacity: 0; } 70% { transform: scale(1.08); } 100% { transform: scale(1); opacity: 1; } }
.pop { animation: pop 0.3s ease-out; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

@media (max-width: 560px) {
  .card { padding: 16px; }
  .site-header .title small { display: none; }
}

/* ---------- Đa ngôn ngữ: chỉ hiện khối đúng ngôn ngữ ---------- */
html[lang="vi"] [data-lang="en"], html[lang="en"] [data-lang="vi"] { display: none !important; }
.lang-btn { font-size: 0.76rem; font-weight: 800; letter-spacing: 0.03em; font-family: var(--mono); }
.theme-btn svg { display: block; }