/* =========================================
   THEME "XANH GIÁO DỤC" — FULL RESET & LAYOUT
   ========================================= */
:root{
  /* Màu & token giao diện */
  --bg1:#0b2a22;        /* nền dưới */
  --bg2:#0f3a2d;        /* nền trên  */
  --panel:#113f31;      /* khối đậm  */
  --panel2:#0f3329;     /* khối phụ  */
  --text:#eafff6;       /* chữ chính */
  --muted:#c8efe1;      /* chữ phụ   */
  --brand:#34d399;      /* nhấn sáng */
  --brand-dk:#059669;   /* nhấn đậm  */
  --good:#22c55e;       /* đúng      */
  --bad:#ef4444;        /* sai       */
  --border:#1a5a49;     /* viền      */
  --radius:18px;        /* bo góc    */
  --shadow:0 16px 44px rgba(0,0,0,.35);
  --gap:14px;           /* khoảng cách lưới */
  --maxw:1200px;
  --transition:.22s cubic-bezier(.22,.61,.36,1);
}

/* Reset nhẹ */
*{ box-sizing:border-box; }
html,body{ height:100%; }
body{
  margin:0;
  font-family:system-ui,-apple-system,Segoe UI,Roboto,"Helvetica Neue",Arial,"Noto Sans",sans-serif;
  color:var(--text);
  background:
    radial-gradient(1200px 600px at 50% -120px, rgba(52,211,153,.20) 0%, transparent 60%),
    linear-gradient(180deg, var(--bg2), var(--bg1));
}

/* =========================================
   KHUNG TRANG CHUNG
   ========================================= */
.page{ min-height:100dvh; display:flex; flex-direction:column; }
.container-inner{ width:min(100% - 32px, var(--maxw)); margin-inline:auto; }
.site-main{ flex:1 1 auto; display:block; padding:18px 0 22px; }

/* =========================================
   HEADER / MENU
   ========================================= */
.site-header{
  position:sticky; top:0; z-index:20;
  background:rgba(9,39,30,.85);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--border);
  box-shadow:0 8px 22px rgba(0,0,0,.25);
}
.site-header .container-inner{
  display:flex; align-items:center; justify-content:space-between; padding:12px 0;
}
.brand{
  color:var(--text); text-decoration:none;
  font-weight:800; font-size:1.1rem; letter-spacing:.3px;
}
.nav{ display:flex; gap:8px; align-items:center; }
.nav-link{
  text-decoration:none; color:var(--muted);
  padding:8px 12px; border-radius:999px; border:1px solid transparent;
  transition:var(--transition);
}
.nav-link:hover,.nav-link.active{
  color:var(--text);
  border-color:var(--border);
  background:rgba(5,150,105,.18);
  box-shadow:0 6px 16px rgba(5,150,105,.22);
}

/* =========================================
   ADSENSE SLOTS (trên cùng & trước footer)
   ========================================= */
.ad-slot{
  display:flex; align-items:center; justify-content:center;
  min-height:90px; margin:12px auto 0;
  border:1px dashed rgba(255,255,255,.18);
  border-radius:16px;
  background:#0c2f25; color:var(--muted);
  text-align:center; padding:8px;
}
.ad-bottom{ margin:18px auto; }
@media (max-width:600px){ .ad-slot{ min-height:50px; } }

/* =========================================
   THANH CHỌN BẢNG NHÂN (×1..×9)
   ========================================= */
.tables-toolbar{
  background:var(--panel);
  border:1px solid var(--border);
  border-radius:16px;
  box-shadow:var(--shadow);
  padding:16px;
  margin:12px 0 8px;
}
.tt-title{
  margin:0 0 10px;
  font-size:clamp(18px,2.4vw,26px);
  font-weight:900; letter-spacing:.2px;
}
.tt-row{
  display:flex; gap:16px; align-items:center;
  justify-content:space-between; flex-wrap:wrap;
}
.tt-group{
  display:grid; gap:8px;
  grid-template-columns:repeat(9, minmax(52px, 1fr));
}
.tt-item{
  display:flex; align-items:center; justify-content:center; gap:6px;
  background:var(--panel2);
  border:1px solid var(--border);
  border-radius:12px; padding:8px 10px;
  font-weight:800;
  user-select:none;
}
.tt-item input{ transform: translateY(1px); }
.tt-actions{ display:flex; gap:8px; }

.btn{
  background:linear-gradient(180deg, var(--brand), var(--brand-dk));
  color:#06271f;
  padding:10px 12px; font-weight:900;
  border:1px solid rgba(255,255,255,.12);
  border-radius:12px; cursor:pointer;
  transition:transform .08s ease, box-shadow var(--transition);
  box-shadow:0 10px 22px rgba(0,0,0,.25);
}
.btn:hover{ transform:translateY(-1px); }
.btn:active{ transform:translateY(0); }
.btn.ghost{ background:var(--panel2); color:var(--text); }

.tt-note{ margin:8px 0 0; color:var(--muted); font-size:14px; opacity:.9; }

/* Responsive cho toolbar */
@media (max-width:820px){ .tt-group{ grid-template-columns:repeat(6, minmax(52px, 1fr)); } }
@media (max-width:560px){ .tt-group{ grid-template-columns:repeat(3, minmax(72px, 1fr)); } }

/* =========================================
   KHỐI GAME NHÂN (điểm, câu hỏi, đáp án, timer)
   ========================================= */
#container{
  width:min(100% - 32px, 920px);
  margin:12px auto 0;
  background:var(--panel);
  border:1px solid var(--border);
  border-radius:var(--radius);
  box-shadow:var(--shadow);
  padding:clamp(14px, 2vw, 22px);
  position:relative;
  overflow:hidden;
}

/* Chip điểm & thời gian */
#score, #timeremaining{
  position:absolute; top:12px;
  padding:8px 12px; border-radius:999px;
  font-weight:800; font-size:14px;
  background:var(--panel2); color:var(--text);
  border:1px solid var(--border);
  box-shadow:0 8px 22px rgba(0,0,0,.25);
}
#score{ left:12px; }
#timeremaining{ right:12px; }
#scorevalue, #timeremainingvalue{ color:var(--brand); }

/* Câu hỏi to, rõ */
#question{
  margin-top:40px;
  text-align:center;
  background:#0f342a;
  border:1px solid var(--border);
  border-radius:16px;
  padding:clamp(16px,3vw,28px);
  box-shadow:inset 0 0 0 1px rgba(255,255,255,.06);
  font-weight:900; letter-spacing:.3px; line-height:1.25;
  font-size:clamp(28px, 4.2vw, 44px);
}

/* Hướng dẫn */
#instruction{
  margin-top:10px; text-align:center;
  color:var(--muted); font-weight:700;
}

/* Lưới đáp án */
#choices{
  margin-top:14px;
  display:grid; gap:var(--gap);
  grid-template-columns:repeat(4, minmax(120px, 1fr));
}
.box{
  background:var(--panel2);
  border:1px solid var(--border);
  border-radius:14px;
  min-height:74px;
  display:grid; place-items:center;
  font-weight:900;
  font-size:clamp(18px,2.2vw,22px);
  cursor:pointer; user-select:none;
  transition:transform .08s ease, box-shadow var(--transition), background var(--transition), border-color var(--transition);
  box-shadow:0 10px 22px rgba(0,0,0,.25);
}
.box:hover{
  transform:translateY(-2px);
  box-shadow:0 18px 40px rgba(0,0,0,.35);
  border-color:rgba(255,255,255,.18);
  background:#114235;
}
.box:active{ transform:translateY(0) scale(.98); }

/* Badge Đúng / Sai (JS thêm .show) */
#correct, #wrong{
  position:absolute; left:50%; top:10px;
  transform:translateX(-50%) translateY(-12px);
  padding:8px 14px; border-radius:999px;
  font-weight:900;
  border:1px solid rgba(255,255,255,.15);
  backdrop-filter:blur(6px);
  box-shadow:var(--shadow);
  opacity:0; pointer-events:none;
  transition:opacity .25s ease, transform .25s ease;
}
#correct{ background:rgba(34,197,94,.92); color:#06271f; }
#wrong{ background:rgba(239,68,68,.92); }
#correct.show, #wrong.show{ opacity:1; transform:translateX(-50%) translateY(0); }

/* Nút bắt đầu / chơi lại */
#startreset{
  margin:16px auto 8px;
  width:min(100%, 280px);
  text-align:center;
  background:linear-gradient(180deg, var(--brand), var(--brand-dk));
  color:#06271f;
  border:1px solid rgba(255,255,255,.12);
  border-radius:14px;
  padding:12px 16px;
  font-weight:900; cursor:pointer;
  box-shadow:0 12px 26px rgba(0,0,0,.28);
  transition:transform .08s ease, box-shadow var(--transition);
}
#startreset:hover{ transform:translateY(-1px); }
#startreset:active{ transform:translateY(0); }

/* Màn hình Game Over (overlay) */
#gameover{
  position:absolute; inset:0;
  display:none;           /* JS bật display:grid */
  place-items:center;
  background:rgba(0,0,0,.45);
  z-index:10;
}
#gameover::before{
  content:attr(data-title);
  display:block;
  background:linear-gradient(180deg, #114a3b, #0c372c);
  border:1px solid var(--border);
  color:var(--text);
  padding:20px; border-radius:16px;
  text-align:center;
  min-width:min(92vw, 420px);
  box-shadow:0 20px 50px rgba(0,0,0,.5);
  font-weight:800; line-height:1.4;
}

/* Đánh dấu ô khi đúng/sai (nếu JS gán class) */
.box.ok{ outline:3px solid rgba(34,197,94,.85); }
.box.bad{ outline:3px solid rgba(239,68,68,.85); }

/* =========================================
   FOOTER
   ========================================= */
.site-footer{
  margin-top:6px;
  border-top:1px solid var(--border);
  background:#0a2a21;
}
.site-footer .container-inner{
  padding:16px 0 20px;
  text-align:center;
  color:var(--muted);
  font-size:14px;
}
.footer-link{ color:var(--text); text-decoration:none; }
.footer-link:hover{ text-decoration:underline; }

/* =========================================
   RESPONSIVE
   ========================================= */
@media (max-width:820px){
  #choices{ grid-template-columns:repeat(2, minmax(140px, 1fr)); }
}
@media (max-width:480px){
  #choices{ grid-template-columns:1fr 1fr; gap:12px; }
  #question{ font-size:clamp(26px, 6vw, 34px); }
  #score, #timeremaining{ font-size:13px; padding:7px 10px; }
}