/* ========== 基础 ========== */
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:-apple-system,"PingFang SC","Microsoft YaHei",sans-serif;background:#f5f7fb;color:#222;line-height:1.5}
h1,h2,h3,h4{font-weight:600}
button{font-family:inherit;cursor:pointer}
input,textarea{font-family:inherit}

/* ========== 顶部 ========== */
.topbar{background:linear-gradient(135deg,#4f7cff,#6a5cff);color:#fff;padding:14px 24px;display:flex;align-items:center;justify-content:space-between;box-shadow:0 2px 8px rgba(0,0,0,.08)}
.topbar h1{font-size:18px}
.topbar nav{display:flex;gap:8px}
.nav-btn{background:rgba(255,255,255,.18);border:0;color:#fff;padding:8px 14px;border-radius:8px;font-size:14px;transition:.2s}
.nav-btn.active,.nav-btn:hover{background:#fff;color:#4f7cff}
.nav-btn:disabled{opacity:.4;cursor:not-allowed}

main{max-width:920px;margin:24px auto;padding:0 16px 60px}
.view{display:none}
.view.active{display:block}

/* ========== 卡片 ========== */
.card{background:#fff;border-radius:12px;padding:18px 22px;margin-bottom:16px;box-shadow:0 1px 3px rgba(0,0,0,.06)}
.card h2{font-size:16px;color:#4f7cff;margin-bottom:12px}
.card h4{font-size:14px;color:#444;margin:12px 0 6px}
.card.center{text-align:center}
.row{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin:10px 0}
.row label{color:#555;font-size:14px;min-width:auto}
input[type=number],input[type=text],textarea{border:1px solid #ddd;border-radius:8px;padding:8px 10px;font-size:14px;outline:none;transition:.2s;min-width:60px}
input:focus,textarea:focus{border-color:#4f7cff;box-shadow:0 0 0 3px rgba(79,124,255,.12)}
.hint{color:#888;font-size:12px}

/* ========== 按钮 ========== */
.btn{background:#eef1f7;border:0;color:#333;padding:9px 16px;border-radius:8px;font-size:14px;transition:.2s}
.btn:hover{background:#e2e7f0}
.btn.primary{background:#4f7cff;color:#fff}
.btn.primary:hover{background:#3b66ee}
.btn.ghost{background:transparent;color:#888;border:1px solid #ddd}
.btn.ghost:hover{background:#f5f5f5}

/* ========== 选项卡 ========== */
.tabs{display:flex;gap:6px;border-bottom:1px solid #eee;margin-bottom:12px}
.tab{background:transparent;border:0;padding:10px 14px;color:#666;font-size:14px;border-bottom:2px solid transparent}
.tab.active{color:#4f7cff;border-color:#4f7cff}
.tab-pane{display:none}
.tab-pane.active{display:block}

.sem-grid,.custom-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:8px 16px}
.sem-grid label,.custom-grid label,.difficulty-row label{display:flex;align-items:center;gap:6px;font-size:14px;color:#444;padding:4px 0}
.difficulty-row{display:flex;gap:18px}

/* ========== 模板 ========== */
.template-list{display:grid;gap:8px;margin-bottom:10px}
.tpl-item{display:flex;justify-content:space-between;align-items:center;background:#f7f9fc;border:1px solid #eaeef5;border-radius:8px;padding:10px 12px}
.tpl-item .tpl-info{font-size:13px;color:#444}
.tpl-item .tpl-info b{color:#4f7cff}
.tpl-actions{display:flex;gap:6px}
.tpl-actions button{padding:4px 10px;font-size:12px}

/* ========== 屏幕做题 ========== */
.big-question{font-size:48px;font-weight:600;color:#222;margin:24px 0;letter-spacing:2px;min-height:70px;display:flex;align-items:center;justify-content:center}
#answerInput{font-size:24px;width:200px;text-align:center;border:2px solid #ddd;border-radius:10px;padding:10px}
.feedback{min-height:28px;margin:14px 0;font-size:16px;font-weight:600}
.feedback.right{color:#28a745}
.feedback.wrong{color:#dc3545}
.progress-bar{height:6px;background:#eee;border-radius:3px;margin-top:18px;overflow:hidden}
#progressFill{height:100%;width:0%;background:linear-gradient(90deg,#4f7cff,#6a5cff);transition:.3s}

/* ========== PDF 预览 ========== */
.pdf-area{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin-bottom:12px}
.pdf-page{background:#fff;border:1px solid #ddd;border-radius:6px;padding:12px;font-size:11px;aspect-ratio:105/148;overflow:hidden}
.pdf-page h3{font-size:13px;text-align:center;margin-bottom:6px;color:#4f7cff}
.pdf-cols{display:grid;grid-template-columns:repeat(3, 1fr);gap:6px}
.pdf-cols.cols-2{grid-template-columns:repeat(2, 1fr);gap:10px}
.pdf-col p{font-size:11px;line-height:1.7;white-space:nowrap}
.pdf-page .draft{border-top:1px dashed #999;margin-top:8px;padding-top:6px}
.draft-line{border-bottom:1px dashed #aaa;height:14px;margin-bottom:2px}

/* ========== 拍照评分 ========== */
.scan-wrap{margin-top:12px;text-align:center}
.scan-wrap canvas{max-width:100%;border:1px dashed #aaa;border-radius:8px;background:#fafafa}

/* ========== 模态框 ========== */
.modal{position:fixed;inset:0;background:rgba(0,0,0,.45);display:flex;align-items:center;justify-content:center;z-index:999}
.modal.hidden{display:none}
.modal-body{background:#fff;border-radius:12px;width:min(720px,92vw);max-height:88vh;overflow:auto;padding:24px}
.modal-body h2{margin-bottom:10px;color:#4f7cff}
.result-list{max-height:50vh;overflow:auto;border:1px solid #eee;border-radius:8px;padding:10px;margin:10px 0;font-size:13px}
.result-list div{padding:3px 0;border-bottom:1px dashed #eee}
.result-list div.wrong{color:#dc3545}
.result-list div.right{color:#28a745}

@media print{
  .topbar,.nav-btn,.row,.btn{display:none !important}
  .pdf-area{grid-template-columns:1fr}
  .pdf-page{page-break-after:always;border:0;aspect-ratio:auto}
}