:root {
  --primary: #4A90D9;
  --primary-dark: #357ABD;
  --primary-light: #e8f0fe;
  --success: #07C160;
  --danger: #E74C3C;
  --warn: #F39C12;
  --text: #1a1a1a;
  --text-2: #555;
  --text-3: #888;
  --bg: #f5f6fa;
  --card: #fff;
  --border: #e8e8e8;
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
  --shadow-hover: 0 8px 30px rgba(74,144,217,0.15);
  --r: 16px;
  --r-sm: 10px;
  --font: -apple-system,"PingFang SC","Microsoft YaHei","Helvetica Neue",sans-serif;
}
*{margin:0;padding:0;box-sizing:border-box;}
body{font-family:var(--font);background:var(--bg);color:var(--text);font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased;}
a{text-decoration:none;color:var(--primary);}
a:hover{color:var(--primary-dark);}

/* ===== Top Nav (minimal) ===== */
.topbar{background:#fff;border-bottom:1px solid var(--border);height:60px;position:sticky;top:0;z-index:100;}
.topbar-in{max-width:800px;margin:0 auto;display:flex;align-items:center;height:60px;padding:0 20px;}
.topbar .logo{font-size:20px;font-weight:700;color:var(--primary);display:flex;align-items:center;gap:8px;}
.topbar .logo span{color:var(--text);}
.topbar .nav{margin-left:auto;display:flex;gap:8px;}
.topbar .nav a{padding:8px 14px;border-radius:8px;font-size:15px;color:var(--text-2);transition:all .2s;}
.topbar .nav a:hover,.topbar .nav a.on{background:var(--primary-light);color:var(--primary);}

/* ===== Buttons ===== */
.btn{display:inline-flex;align-items:center;justify-content:center;height:44px;padding:0 24px;border-radius:var(--r-sm);font-size:16px;font-weight:500;cursor:pointer;transition:all .2s;border:1px solid var(--border);background:#fff;color:var(--text);text-decoration:none;gap:6px;}
.btn:hover{border-color:var(--primary);color:var(--primary);}
.btn-primary{background:var(--primary);border-color:var(--primary);color:#fff;}
.btn-primary:hover{background:var(--primary-dark);border-color:var(--primary-dark);color:#fff;}
.btn-success{background:var(--success);border-color:var(--success);color:#fff;}
.btn-success:hover{background:#06ad56;border-color:#06ad56;color:#fff;}
.btn-lg{height:52px;padding:0 32px;font-size:18px;border-radius:var(--r);}
.btn-sm{height:36px;padding:0 16px;font-size:14px;}

/* ===== Homepage - 驾校一点通 style ===== */
.home-wrap{max-width:800px;margin:0 auto;padding:40px 20px 20px;}
.home-logo{text-align:center;margin-bottom:32px;}
.home-logo h1{font-size:28px;font-weight:700;color:var(--primary);margin-bottom:6px;}
.home-logo p{font-size:15px;color:var(--text-3);}

/* Search box */
.search-box{max-width:600px;margin:0 auto 36px;position:relative;}
.search-box input{width:100%;height:54px;padding:0 20px 0 50px;border:2px solid var(--border);border-radius:var(--r);font-size:17px;outline:none;transition:all .2s;background:var(--card);}
.search-box input:focus{border-color:var(--primary);box-shadow:0 0 0 4px rgba(74,144,217,0.12);}
.search-box .search-icon{position:absolute;left:18px;top:50%;transform:translateY(-50%);font-size:22px;color:var(--text-3);pointer-events:none;}

/* 4 function cards - 2x2 grid */
.func-grid{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-bottom:24px;}
.func-card{background:var(--card);border-radius:var(--r);padding:32px 24px;text-align:center;border:1px solid var(--border);box-shadow:var(--shadow);transition:all .25s;cursor:pointer;display:block;text-decoration:none;color:var(--text);}
.func-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-hover);border-color:var(--primary);}
.func-card .icon{font-size:44px;display:block;margin-bottom:12px;}
.func-card .title{font-size:20px;font-weight:600;display:block;margin-bottom:4px;color:var(--text);}
.func-card .desc{font-size:14px;color:var(--text-3);display:block;}
.func-card.color1{border-top:4px solid var(--primary);}
.func-card.color2{border-top:4px solid var(--success);}
.func-card.color3{border-top:4px solid var(--warn);}
.func-card.color4{border-top:4px solid var(--danger);}

/* ===== Practice (刷题) page ===== */
.prac-wrap{max-width:820px;margin:0 auto;padding:20px;}
.prac-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:16px;}

/* Progress bar */
.progress-section{margin-bottom:20px;}
.progress-row{display:flex;align-items:center;gap:12px;margin-bottom:6px;}
.progress-label{font-size:14px;color:var(--text-2);font-weight:500;}
.progress-text{font-size:14px;color:var(--primary);font-weight:600;white-space:nowrap;}
.progress-track{flex:1;height:6px;background:#e8e8e8;border-radius:6px;overflow:hidden;}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--primary),#6bb3ff);border-radius:6px;transition:width .4s ease;}

/* Question card */
.q-card{background:var(--card);border-radius:var(--r);padding:28px;box-shadow:var(--shadow);border:1px solid var(--border);margin-bottom:16px;}
.q-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:16px;padding-bottom:14px;border-bottom:2px solid var(--bg);}
.q-num{font-size:15px;font-weight:600;color:var(--primary);}
.q-type{font-size:13px;padding:3px 12px;border-radius:20px;background:var(--primary-light);color:var(--primary);font-weight:500;}
.q-text{font-size:17px;line-height:1.8;margin-bottom:20px;color:var(--text);}

/* Options */
.q-options{display:flex;flex-direction:column;gap:10px;}
.q-opt{padding:14px 18px;border:2px solid var(--border);border-radius:var(--r-sm);cursor:pointer;transition:all .15s;font-size:16px;display:flex;align-items:flex-start;gap:10px;background:var(--card);}
.q-opt:hover{border-color:var(--primary);background:var(--primary-light);}
.q-opt.selected{border-color:var(--primary);background:var(--primary-light);color:var(--primary);}
.q-opt.correct{border-color:var(--success);background:#f0faf4;color:var(--success);}
.q-opt.correct .opt-label{background:var(--success);color:#fff;}
.q-opt.wrong{border-color:var(--danger);background:#fef0ef;color:var(--danger);}
.q-opt.wrong .opt-label{background:var(--danger);color:#fff;}
.q-opt .opt-label{width:28px;height:28px;border-radius:50%;background:#f0f0f0;display:flex;align-items:center;justify-content:center;font-weight:600;font-size:14px;flex-shrink:0;transition:all .15s;}

/* Analysis box - shown immediately after answering */
.analysis-box{background:#f8faff;border-radius:var(--r-sm);padding:20px;margin-top:16px;border-left:4px solid var(--primary);display:none;}
.analysis-box .tag{display:inline-block;padding:3px 12px;border-radius:4px;font-size:13px;font-weight:600;margin-bottom:10px;}
.analysis-box .tag.correct{background:#f0faf4;color:var(--success);}
.analysis-box .tag.wrong{background:#fef0ef;color:var(--danger);}
.analysis-box .answer-label{font-size:14px;font-weight:600;color:var(--success);margin-bottom:8px;}
.analysis-box .analysis-text{font-size:15px;line-height:1.8;color:var(--text-2);}

/* Practice action buttons */
.prac-actions{display:flex;gap:12px;justify-content:center;margin-top:12px;}
.prac-actions .btn{min-width:120px;}

/* Result card */
.result-section{text-align:center;padding:60px 20px;}
.result-card{background:var(--card);border-radius:var(--r);padding:48px 32px;box-shadow:var(--shadow);max-width:400px;margin:0 auto;border:1px solid var(--border);}
.result-score{font-size:56px;font-weight:700;color:var(--primary);}
.result-label{font-size:16px;color:var(--text-2);margin-top:4px;margin-bottom:20px;}
.result-actions{display:flex;gap:12px;justify-content:center;}

/* ===== Category page ===== */
.cat-wrap{max-width:800px;margin:0 auto;padding:24px 20px;}
.cat-title{font-size:22px;font-weight:600;margin-bottom:20px;}
.sub-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;}
.sub-card{background:var(--card);border-radius:var(--r);padding:28px 20px;border:1px solid var(--border);box-shadow:var(--shadow);transition:all .2s;display:block;text-align:center;}
.sub-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-hover);border-color:var(--primary);}
.sub-card .nm{font-size:17px;font-weight:600;color:var(--text);}
.sub-card .de{font-size:13px;color:var(--primary);margin-top:6px;}
.sub-card .icon{font-size:36px;display:block;margin-bottom:10px;}

/* ===== Knowledge Points Panel ===== */
.kp-panel{background:var(--card);border-radius:var(--r);padding:20px;margin-bottom:20px;border:1px solid var(--border);box-shadow:var(--shadow);}
.kp-panel-title{font-size:16px;font-weight:600;margin-bottom:14px;color:var(--text);}
.kp-group{border-bottom:1px solid var(--bg);padding:4px 0;}
.kp-group:last-child{border-bottom:none;}
.kp-group-title{padding:8px 4px;cursor:pointer;border-radius:6px;font-size:15px;display:flex;align-items:center;gap:8px;transition:background .1s;color:var(--text-2);}
.kp-group-title:hover{background:var(--primary-light);color:var(--primary);}
.kp-group .arrow{font-size:12px;transition:transform .2s;display:inline-block;}
.kp-group.open .arrow{transform:rotate(90deg);}
.kp-children{display:none;padding-left:20px;padding-bottom:6px;}
.kp-group.open .kp-children{display:block;}
.kp-child{display:block;padding:7px 10px;border-radius:6px;font-size:14px;color:var(--text-2);transition:all .1s;margin-bottom:2px;}
.kp-child:hover,.kp-child.active{background:var(--primary-light);color:var(--primary);}

/* ===== Footer ===== */
.ft{text-align:center;padding:24px 20px;color:var(--text-3);font-size:13px;margin-top:40px;border-top:1px solid var(--border);}

/* ===== Responsive ===== */
@media(max-width:640px){
  .home-wrap{padding:24px 16px 16px;}
  .home-logo h1{font-size:24px;}
  .func-grid{gap:12px;}
  .func-card{padding:24px 16px;}
  .func-card .icon{font-size:36px;}
  .func-card .title{font-size:18px;}
  .q-card{padding:20px;}
  .q-text{font-size:16px;}
  .q-opt{padding:12px 14px;font-size:15px;}
  .prac-wrap{padding:12px;}
  .sub-grid{grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:10px;}
  .result-score{font-size:44px;}
}