* { box-sizing: border-box; }
body { margin: 0; font-family: Segoe UI, Arial, sans-serif; background: #f3f5f8; color: #1d232b; }
header { position: sticky; top: 0; z-index: 10; background: #232f3e; color: #fff; padding: 12px 24px 0; }
header h1 { margin: 0 0 10px; font-size: 20px; }
#tabs { display: flex; gap: 4px; }
#tabs button { border: 0; background: #37475a; color: #fff; padding: 10px 18px; cursor: pointer; font-size: 14px; border-radius: 6px 6px 0 0; }
#tabs button[aria-selected="true"] { background: #f3f5f8; color: #232f3e; font-weight: 600; }
main { max-width: 1000px; margin: 0 auto; padding: 16px; }
#toolbar { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; margin-bottom: 16px; font-size: 14px; }
#score { font-weight: 600; margin-right: auto; }
#jump { width: 70px; }
.q { background: #fff; border-radius: 8px; padding: 18px 22px; margin-bottom: 18px; box-shadow: 0 1px 3px rgba(0,0,0,.08); scroll-margin-top: 120px; }
.q h2 { margin: 0 0 8px; font-size: 16px; color: #ff9900; }
.q .src { font-weight: normal; color: #8a94a3; font-size: 12px; margin-left: 8px; }
.q p { margin: 0 0 10px; line-height: 1.5; white-space: pre-line; }
.q .hint { font-size: 13px; color: #5a6472; margin-bottom: 8px; }
.q .exhibit { display: block; max-width: 100%; margin: 0 0 12px; border: 1px solid #dde2e8; border-radius: 6px; }
.opt { display: flex; align-items: flex-start; gap: 10px; padding: 8px 10px; border: 1px solid #dde2e8; border-radius: 6px; margin-bottom: 6px; cursor: pointer; line-height: 1.45; }
.opt:hover { background: #f7f9fb; }
.opt input { margin-top: 4px; flex: none; }
.opt .txt { flex: 1; }
.opt.correct { background: #e3f6e8; border-color: #2ea44f; }
.opt.wrong { background: #fde8e8; border-color: #d73a49; }
.opt.missed { border: 2px dashed #2ea44f; }
.why-btn { flex: none; width: 24px; height: 24px; border-radius: 50%; border: 0; background: #d73a49; color: #fff; font-weight: 700; cursor: pointer; }
.why-wrong { display: none; margin: -2px 0 8px 34px; padding: 8px 12px; border-left: 4px solid #d73a49; background: #fff5f5; font-size: 14px; line-height: 1.45; }
.why-wrong.open { display: block; }
details.why-right { margin-top: 10px; border: 1px solid #2ea44f; background: #e3f6e8; border-radius: 6px; padding: 8px 12px; }
details.why-right summary { cursor: pointer; font-weight: 600; color: #1a7f37; }
details.why-right div { margin-top: 8px; line-height: 1.5; font-size: 14px; }
.result { margin-top: 8px; font-weight: 600; }
.result.ok { color: #1a7f37; }
.result.bad { color: #d73a49; }
.hidden { display: none; }
#pager { display: flex; justify-content: center; align-items: center; gap: 18px; margin: 8px 0 24px; }
#pager button { border: 0; background: #232f3e; color: #fff; padding: 10px 22px; border-radius: 6px; font-size: 15px; cursor: pointer; }
#pager button:disabled { opacity: .35; cursor: default; }
#counter { font-weight: 600; min-width: 90px; text-align: center; }
.empty { text-align: center; color: #5a6472; }