:root{
  --navy:#1b3a6b; --red:#d92121; --green:#0b8a3c; --amber:#f59e0b;
  --card:#fff; --ink:#1f2937; --muted:#64748b;
  --radius:18px; --shadow:0 6px 24px rgba(27,58,107,.12);
}
*{box-sizing:border-box}
body{
  margin:0; padding:20px 14px 60px;
  font-family:"Segoe UI",system-ui,-apple-system,"Helvetica Neue",Arial,sans-serif;
  background:linear-gradient(180deg,#eef4fb 0%,#e3ecf8 100%);
  color:var(--ink); line-height:1.6;
}
.wrap{max-width:880px;margin:0 auto}

/* ---------------- header ---------------- */
header{text-align:center;margin-bottom:18px;position:relative}
.badge{display:inline-block;background:var(--navy);color:#fff;font-weight:700;
  font-size:13px;letter-spacing:.06em;padding:5px 14px;border-radius:999px}
h1{margin:10px 0 2px;font-size:28px;color:var(--red);letter-spacing:.5px}
.sub{margin:0;font-size:17px;font-weight:700;color:var(--navy)}
.home-link{position:absolute;left:0;top:4px;color:var(--navy);text-decoration:none;
  font-weight:700;font-size:14px;background:#fff;border:1px solid #d7e3f4;
  padding:5px 12px;border-radius:999px;box-shadow:var(--shadow)}
.home-link:hover{background:#eef4fb}

/* ---------------- tiến độ ---------------- */
.bar{display:flex;align-items:center;gap:12px;margin:18px 0 14px}
.track{flex:1;height:12px;background:#d7e3f4;border-radius:999px;overflow:hidden}
.fill{height:100%;width:0;background:linear-gradient(90deg,#22c55e,#0b8a3c);
  border-radius:999px;transition:width .35s ease}
.score{font-weight:800;color:var(--navy);white-space:nowrap;font-size:15px}

.card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:24px 26px;border:1px solid #e2e9f4}

/* ---------------- câu hỏi ---------------- */
.qhead{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:10px}
.qcode{background:#fee2e2;color:var(--red);font-weight:800;padding:4px 12px;
  border-radius:999px;font-size:14px}
.qnum{color:var(--muted);font-size:14px;font-weight:600}
.q-en{font-size:16px;font-weight:600;color:var(--navy);margin:0 0 4px}
.q-vi{font-size:16px;font-style:italic;color:#475569;margin:0 0 18px}
/* đề vòng chung kết TIMO không có bản dịch, sách chỉ cho bảng từ vựng */
.gloss{font-size:14px;color:#6b5330;background:#fffaf3;border-left:4px solid #e7c9a5;
  border-radius:0 10px 10px 0;padding:8px 12px;margin:0 0 18px}

.seq{text-align:center;margin:18px 0 22px;overflow-x:auto}
.seq img{max-width:100%;height:auto}
.seq img + img{margin-top:10px}
.seq-text{font-size:30px;font-weight:800;color:#7a3b12;letter-spacing:2px;
  background:#fffaf3;border:2px dashed #e7c9a5;border-radius:14px;padding:18px 12px;
  display:inline-block;max-width:100%}

/* ---------------- ô trả lời ---------------- */
.answer-row{display:flex;gap:10px;flex-wrap:wrap;align-items:center;justify-content:center}
label.lbl{font-weight:700;color:var(--navy);font-size:16px}
input[type=text]{
  font-size:26px;font-weight:800;text-align:center;width:160px;padding:10px 12px;
  border:3px solid #cbd5e1;border-radius:14px;outline:none;color:var(--navy);
  transition:border-color .2s,box-shadow .2s;font-family:inherit}
input[type=text]:focus{border-color:var(--navy);box-shadow:0 0 0 4px rgba(27,58,107,.12)}
input.ok{border-color:var(--green);background:#f0fdf4}
input.no{border-color:var(--red);background:#fef2f2;animation:shake .35s}
@keyframes shake{0%,100%{transform:translateX(0)}25%{transform:translateX(-7px)}75%{transform:translateX(7px)}}

/* ---------------- trắc nghiệm hình ---------------- */
.choices{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;margin-bottom:18px}
.choice{display:flex;flex-direction:column;align-items:center;gap:4px;
  background:#fff;border:3px solid #cbd5e1;border-radius:16px;padding:12px 18px;
  cursor:pointer;color:var(--navy);min-width:86px;transition:.15s}
.choice:hover{border-color:var(--navy);transform:translateY(-2px)}
.choice .ckey{font-weight:800;font-size:15px;color:var(--muted)}
.choice .ctext{font-size:20px;font-weight:800}
/* đáp án in bằng hình (dãy hình có quy luật, khối lập phương…) */
.choice .cimg{max-width:120px;max-height:76px;width:auto;height:auto;display:block}
.choice.sel{border-color:var(--navy);background:#eef4fb;box-shadow:0 0 0 4px rgba(27,58,107,.12)}
.choice.ok{border-color:var(--green);background:#f0fdf4;color:var(--green)}
.choice.ok .ckey{color:var(--green)}
.choice.no{border-color:var(--red);background:#fef2f2;color:var(--red);animation:shake .35s}
.choice.no .ckey{color:var(--red)}

/* ---------------- nút ---------------- */
button{font-family:inherit;font-size:16px;font-weight:700;padding:11px 22px;border:0;
  border-radius:14px;cursor:pointer;transition:transform .12s,filter .15s}
button:active{transform:translateY(1px)}
button:disabled{opacity:.5;cursor:not-allowed}
.btn-check{background:var(--navy);color:#fff}
.btn-check:hover:not(:disabled){filter:brightness(1.15)}
.btn-ghost{background:#eef2f7;color:var(--navy)}
.btn-ghost:hover:not(:disabled){background:#dde6f2}
.btn-next{background:var(--green);color:#fff}
.btn-next:hover:not(:disabled){filter:brightness(1.12)}
.btn-link{display:inline-block;padding:11px 22px;border-radius:14px;font-weight:700;
  color:var(--navy);background:#eef2f7;text-decoration:none}
.btn-link:hover{background:#dde6f2}

/* ---------------- phản hồi & lời giải ---------------- */
.feedback{margin-top:16px;text-align:center;font-size:18px;font-weight:800;min-height:28px}
.feedback.ok{color:var(--green)}
.feedback.no{color:var(--red)}
.feedback.hint{color:var(--amber);font-weight:700;font-size:16px}

.intro{background:#eef5ff;border:2px solid #c7dcfa;border-radius:14px;
  padding:12px 16px;margin-bottom:14px;color:#1e3a5f}
.intro b{display:block;margin-bottom:6px;color:var(--navy);font-size:15px}
.intro ol{margin:0;padding-left:22px}
.intro li{margin:3px 0;font-size:14.5px}

.solution{margin-top:20px;border-top:2px dashed #dbe4f0;padding-top:18px;display:none}
.solution.show{display:block;animation:fade .3s ease}
@keyframes fade{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:none}}
.rule{background:#fff7ed;border-left:5px solid var(--amber);padding:10px 14px;
  border-radius:0 12px 12px 0;font-weight:700;color:#92400e;margin-bottom:14px}
.sol-title{font-weight:800;color:var(--navy);margin:0 0 10px;font-size:17px}
ol.steps{margin:0;padding-left:22px}
ol.steps li{margin-bottom:9px;color:#334155}
.final{margin-top:14px;text-align:center;font-size:22px;font-weight:800;color:var(--green);
  background:#dcfce7;border:2px solid var(--green);border-radius:14px;padding:10px}

.nav{display:flex;justify-content:space-between;gap:10px;margin-top:22px;flex-wrap:wrap}

.dots{display:flex;gap:7px;justify-content:center;flex-wrap:wrap;margin-top:20px}
.dot{width:34px;height:34px;border-radius:10px;border:2px solid #cbd5e1;background:#fff;
  font-weight:800;font-size:14px;color:var(--muted);cursor:pointer;line-height:1;
  display:flex;align-items:center;justify-content:center;transition:.15s}
.dot:hover{border-color:var(--navy)}
.dot.cur{border-color:var(--navy);background:var(--navy);color:#fff}
.dot.ok{border-color:var(--green);background:#dcfce7;color:var(--green)}
.dot.no{border-color:var(--red);background:#fee2e2;color:var(--red)}

.done{text-align:center;padding:14px 4px}
.done h2{font-size:30px;color:var(--navy);margin:8px 0}
.done .big{font-size:56px;font-weight:900;color:var(--green);margin:6px 0}
.done p{font-size:17px;color:#475569}

/* ---------------- trang danh sách ngày ---------------- */
.daylist{display:grid;gap:16px;grid-template-columns:repeat(auto-fit,minmax(330px,1fr))}
.daycard{display:flex;flex-direction:column;gap:10px;text-decoration:none;color:inherit;
  background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  border:1px solid #e2e9f4;border-top:6px solid var(--navy);padding:20px 22px;
  transition:transform .15s,box-shadow .15s}
.daycard:hover{transform:translateY(-4px);box-shadow:0 12px 30px rgba(27,58,107,.2)}
.daycard .top{display:flex;align-items:center;gap:12px}
.daycard .ico{font-size:34px;line-height:1}
.daycard .dnum{font-size:13px;font-weight:800;letter-spacing:.08em;color:var(--muted);
  text-transform:uppercase}
.daycard h3{margin:2px 0 0;font-size:20px;color:var(--navy)}
.daycard .ten{margin:0;font-size:13px;font-weight:700;color:var(--red);letter-spacing:.04em}
.daycard .desc{margin:0;font-size:15px;color:#475569}
.daycard .meta{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:auto;
  padding-top:8px;font-size:14px;font-weight:700;color:var(--muted)}
.pill{background:#eef4fb;color:var(--navy);padding:3px 11px;border-radius:999px}
.pill.done{background:#dcfce7;color:var(--green)}
.daycard .mini{flex:1;height:8px;background:#e6edf7;border-radius:999px;overflow:hidden;min-width:70px}
.daycard .mini i{display:block;height:100%;background:linear-gradient(90deg,#22c55e,#0b8a3c)}
.go{align-self:flex-start;background:var(--navy);color:#fff;font-weight:700;font-size:15px;
  padding:9px 18px;border-radius:12px}
.tools{text-align:center;margin-top:22px}

/* tiêu đề mục — dùng khi một trang có nhiều danh sách (Lớp 3: chủ đề + ngày) */
.secttl{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap;
  margin:30px 0 14px;padding-bottom:8px;border-bottom:3px solid #dbe4f0;
  font-size:22px;color:var(--navy)}
.secttl span{font-size:14px;font-weight:700;color:var(--muted)}

/* ---------------- trang chọn lớp ---------------- */
.gradelist{display:grid;gap:18px;grid-template-columns:repeat(auto-fit,minmax(330px,1fr))}
.gradecard{display:flex;gap:16px;align-items:flex-start;text-decoration:none;color:inherit;
  background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  border:1px solid #e2e9f4;border-top:6px solid var(--navy);padding:22px 24px;
  transition:transform .15s,box-shadow .15s;flex-wrap:wrap}
.gradecard:hover{transform:translateY(-4px);box-shadow:0 12px 30px rgba(27,58,107,.2)}
.gradecard .gico{font-size:38px;line-height:1;border-radius:16px;padding:12px 14px}
.gradecard .gbody{flex:1;min-width:190px}
.gradecard .gnum{font-size:13px;font-weight:800;letter-spacing:.08em;color:var(--muted);
  text-transform:uppercase}
.gradecard h3{margin:2px 0 6px;font-size:22px;color:var(--navy)}
.gradecard .desc{margin:0;font-size:15px;color:#475569}
.gradecard .meta{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-top:12px;
  font-size:14px;font-weight:700;color:var(--muted)}
.gradecard .mini{flex:1;height:8px;background:#e6edf7;border-radius:999px;overflow:hidden;min-width:70px}
.gradecard .mini i{display:block;height:100%;background:linear-gradient(90deg,#22c55e,#0b8a3c)}
.gradecard .go{align-self:center}

/* ---------------- tab Từ vựng / Luyện tập ---------------- */
.tabs{display:flex;gap:8px;justify-content:center;margin:18px 0 16px;flex-wrap:wrap}
.tab{background:#fff;color:var(--navy);border:2px solid #d7e3f4;border-radius:999px;
  padding:9px 20px;font-size:15px;box-shadow:var(--shadow)}
.tab:hover{background:#eef4fb}
.tab.cur{background:var(--navy);color:#fff;border-color:var(--navy)}

/* ---------------- phần 1: từ vựng & lý thuyết ---------------- */
.lesson-toc{background:#fff7ed;border:2px solid #fcd9a8;border-radius:14px;
  padding:12px 18px;margin-bottom:18px;color:#92400e}
.lesson-toc b{font-size:15px}
.lesson-toc ol{margin:6px 0 0;padding-left:22px}
.lesson-toc li{margin:3px 0;font-weight:700}
.toc-en{font-weight:500;font-style:italic;color:#b45309;font-size:14px}

.lesson{margin-bottom:18px}
.lhead{display:flex;align-items:center;gap:12px;padding-bottom:12px;margin-bottom:14px;
  border-bottom:2px dashed #dbe4f0}
.lno{background:var(--navy);color:#fff;font-weight:800;font-size:14px;
  padding:6px 14px;border-radius:999px;white-space:nowrap}
.lhead h3{margin:2px 0 0;font-size:20px;color:var(--navy)}
.lhead .ten{margin:0;font-size:13px;font-weight:700;color:var(--red);letter-spacing:.04em}

h4.sec{margin:18px 0 10px;font-size:16px;color:var(--navy)}

table.vocab{width:100%;border-collapse:collapse;font-size:15px}
table.vocab th{background:var(--navy);color:#fff;font-size:13px;letter-spacing:.05em;
  padding:7px 10px;text-align:left}
table.vocab th:first-child{width:38px;text-align:center;border-radius:10px 0 0 0}
table.vocab th:last-child{border-radius:0 10px 0 0}
table.vocab td{padding:7px 10px;border-bottom:1px solid #e6edf7}
table.vocab td:first-child{text-align:center;color:var(--muted);font-weight:700}
table.vocab td.en{font-weight:800;color:var(--navy)}
table.vocab tr:nth-child(even) td{background:#f7faff}

ul.method{margin:0;padding-left:22px;background:#f0fdf4;border-left:5px solid var(--green);
  border-radius:0 12px 12px 0;padding:12px 12px 12px 34px}
ul.method li{margin:5px 0;color:#14532d;font-weight:600}

.example{background:#f8fafc;border:1px solid #e2e9f4;border-radius:14px;
  padding:14px 18px;margin-bottom:14px}
.exno{display:inline-block;background:#fef3c7;color:#92400e;font-weight:800;font-size:13px;
  padding:3px 12px;border-radius:999px;margin-bottom:8px}
.example .q-vi{margin-bottom:10px}
.example .seq{margin:10px 0 14px}
.example .seq-text{font-size:24px}
.example .final{font-size:18px;padding:7px}

footer{text-align:center;color:var(--muted);font-size:13px;margin-top:26px}
.err{background:#fef2f2;border:2px solid var(--red);color:#991b1b;padding:16px;border-radius:14px}

@media(max-width:560px){
  h1{font-size:22px}
  .card{padding:18px 16px}
  .seq-text{font-size:22px}
  input[type=text]{width:130px;font-size:22px}
  .home-link{position:static;display:inline-block;margin-bottom:12px}
  .daylist{grid-template-columns:1fr}
  .gradelist{grid-template-columns:1fr}
  .gradecard{padding:18px 16px}
  .tab{padding:8px 14px;font-size:14px}
  table.vocab{font-size:14px}
  .lhead{flex-wrap:wrap}
}