/* ============================================================
   ROS2 教程实验页公共样式 (exp003-ros2-application)
   引用: <link rel="stylesheet" href="../shared/tutorial.css">
   ============================================================ */
:root{
  --bg-base:#f8fafc; --bg-card:#fff; --bg-soft:#f1f5f9; --bg-tint:#fffbeb;
  --border:#e2e8f0; --text:#0f172a; --muted:#64748b; --head:#1e293b;
  --accent-blue:#2563eb; --accent-teal:#0d9488; --accent-amber:#d97706;
  --accent-violet:#7c3aed; --accent-rose:#e11d48; --accent-cyan:#0891b2;
  --theme:#d97706; --theme-deep:#b45309; --theme-bg:#fef3c7; --theme-bd:#fde68a;
  --font-mono:'Cascadia Code','JetBrains Mono',Consolas,'Noto Sans Mono CJK SC',monospace;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:'Noto Sans CJK SC','Microsoft YaHei',sans-serif;background:var(--bg-base);color:var(--text);line-height:1.75;font-size:15.5px}
a{color:var(--accent-blue);text-decoration:none}
main a:hover{text-decoration:underline}

/* topbar */
.topbar{position:sticky;top:0;z-index:50;background:rgba(255,255,255,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--border);padding:0 24px;height:56px;display:flex;align-items:center;justify-content:space-between}
.logo{font-weight:700;font-size:15px;color:var(--head)}
.logo i{font-style:normal;color:var(--theme)}
.crumb{font-size:13px;color:var(--muted)}
.crumb a{color:var(--muted)}
.crumb a:hover{color:var(--theme)}

/* layout */
.wrap{display:grid;grid-template-columns:240px 1fr;max-width:1280px;margin:0 auto;gap:0}
.side{position:sticky;top:56px;align-self:start;height:calc(100vh - 56px);overflow-y:auto;padding:24px 16px 40px 24px;border-right:1px solid var(--border);background:#fff}
.side h4{font-size:11px;letter-spacing:.12em;color:var(--muted);text-transform:uppercase;margin:18px 0 8px}
.side h4:first-child{margin-top:0}
.side a{display:block;font-size:13px;color:#475569;padding:5px 10px;border-radius:8px;margin-bottom:2px}
.side a:hover{background:var(--bg-soft);text-decoration:none}
.side a.now{background:var(--theme-bg);color:var(--theme-deep);font-weight:600;border-left:3px solid var(--theme)}
.content{padding:32px 40px 80px;min-width:0}

/* exp head */
.exp-head{margin-bottom:28px}
.exp-head .code{display:inline-block;font-family:var(--font-mono);font-size:12px;font-weight:700;color:var(--theme-deep);background:var(--theme-bg);border:1px solid var(--theme-bd);border-radius:6px;padding:2px 10px;letter-spacing:.08em;margin-bottom:10px}
.exp-head h1{font-size:30px;color:var(--head);line-height:1.3;margin-bottom:8px}
.exp-head .desc{color:var(--muted);font-size:15px;max-width:760px}
.meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
.tag{font-size:12px;background:var(--bg-soft);border:1px solid var(--border);border-radius:999px;padding:3px 12px;color:#475569}
.tag.hl{background:#ecfdf5;border-color:#a7f3d0;color:#047857}

/* sections */
.blk{background:var(--bg-card);border:1px solid var(--border);border-radius:16px;padding:28px 30px;margin-bottom:22px;opacity:0;transform:translateY(18px);transition:opacity .6s ease,transform .6s ease}
.blk.on{opacity:1;transform:none}
.blk h2{font-size:20px;color:var(--head);margin-bottom:16px;display:flex;align-items:center;gap:10px}
.blk h2 .no{font-family:var(--font-mono);font-size:13px;background:var(--head);color:#fff;border-radius:8px;padding:2px 9px;letter-spacing:.05em}
.blk h3{font-size:16px;color:var(--head);margin:20px 0 10px}
.blk p{margin-bottom:10px}
.blk ul,.blk ol{padding-left:22px;margin-bottom:12px}
.blk li{margin-bottom:6px}
strong{color:var(--head)}
code{font-family:var(--font-mono);font-size:.9em;background:var(--bg-soft);border:1px solid var(--border);border-radius:5px;padding:1px 6px}
pre{font-family:var(--font-mono);font-size:13px;line-height:1.7;background:#0f172a;color:#e2e8f0;border-radius:12px;padding:16px 18px;overflow-x:auto;margin:12px 0}
pre .c{color:#64748b}pre .g{color:#4ade80}pre .b{color:#60a5fa}pre .y{color:#fbbf24}
code.inline{background:#fef3c7;border-color:#fde68a;color:#92400e;padding:1px 6px}

/* flow */
.flow{display:flex;flex-direction:column;gap:0;margin:14px 0}
.step{background:var(--bg-soft);border:1px solid var(--border);border-radius:12px;padding:14px 18px;position:relative}
.step .n{display:inline-block;font-family:var(--font-mono);font-size:12px;font-weight:700;background:var(--theme);color:#fff;border-radius:999px;min-width:22px;height:22px;text-align:center;line-height:22px;margin-right:8px;padding:0 4px}
.arr{width:2px;height:18px;background:linear-gradient(#fbbf24,var(--theme));margin:0 auto;position:relative}
.arr::after{content:'';position:absolute;bottom:-2px;left:-4px;border:5px solid transparent;border-top-color:var(--theme)}

/* grids */
.kgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:12px;margin:14px 0}
.kcard{background:var(--bg-soft);border:1px solid var(--border);border-radius:12px;padding:14px 16px}
.kcard .kd{font-size:12px;color:var(--theme);font-weight:700;letter-spacing:.06em;margin-bottom:6px}
.kcard .kt{font-size:14.5px;color:var(--head);font-weight:600;margin-bottom:4px}
.kcard p{font-size:13.5px;color:#475569;margin:0}

/* table */
table{width:100%;border-collapse:collapse;font-size:14px;margin:12px 0}
th{background:var(--bg-soft);color:var(--head);text-align:left;padding:9px 12px;border:1px solid var(--border);font-weight:600}
td{padding:9px 12px;border:1px solid var(--border);vertical-align:top}
tr:nth-child(even) td{background:#fcfdfe}

/* tip */
.tip{border-radius:12px;padding:14px 18px;margin:14px 0;font-size:14.5px;border:1px solid}
.tip .lab{font-weight:700;display:block;margin-bottom:4px}
.tip.amber{background:#fffbeb;border-color:#fde68a;color:#78350f}
.tip.tealb{background:#f0fdfa;border-color:#99f6e4;color:#115e59}
.tip.violet{background:#f5f3ff;border-color:#ddd6fe;color:#5b21b6}

/* check */
.check{list-style:none;padding:0}
.check li{padding:8px 0 8px 30px;position:relative;border-bottom:1px dashed var(--border);margin:0}
.check li::before{content:'✓';position:absolute;left:4px;top:8px;color:var(--accent-teal);font-weight:700}

/* svg animation */
.anim-box{background:linear-gradient(160deg,#0f172a,#1e293b);border-radius:16px;padding:20px;margin:16px 0;overflow-x:auto}
.anim-box svg{display:block;margin:0 auto;max-width:100%;height:auto}
.anim-cap{text-align:center;font-size:13px;color:#94a3b8;margin-top:10px}

/* interaction */
.ix-panel{background:#10151f;border:1px solid #1e293b;border-radius:16px;padding:22px 24px;margin:16px 0;color:#e2e8f0;font-family:var(--font-mono),sans-serif}
.ix-panel .ix-title{font-size:14px;font-weight:700;color:#fbbf24;letter-spacing:.08em;margin-bottom:14px;display:flex;align-items:center;gap:8px}
.ix-panel .ix-title::before{content:'⚡'}
.ctl-row{display:flex;flex-wrap:wrap;gap:14px;align-items:center;margin-bottom:14px}
.ctl{display:flex;flex-direction:column;gap:5px;font-size:12px;color:#94a3b8}
.ctl select,.ctl input[type=range],.ctl input[type=number]{background:#1e293b;color:#e2e8f0;border:1px solid #334155;border-radius:8px;padding:7px 10px;font-family:var(--font-mono);font-size:13px;min-width:130px}
.ctl input[type=range]{padding:0;accent-color:#fbbf24;height:26px}
.btn{background:#d97706;color:#fff;border:none;border-radius:9px;padding:9px 20px;font-size:13.5px;font-weight:700;font-family:inherit;cursor:pointer}
.btn:hover{background:#f59e0b}
.btn.ghost{background:transparent;color:#fbbf24;border:1px solid #92400e}
.btn:disabled{opacity:.4;cursor:not-allowed}
.io{background:#0b0f17;border:1px solid #1e293b;border-radius:10px;padding:14px 16px;font-size:13px;line-height:1.9;white-space:pre-wrap;min-height:56px}
.io .ok{color:#4ade80}.io .warn{color:#fbbf24}.io .bad{color:#f87171}.io .dim{color:#64748b}

/* levels */
.levels{list-style:none;padding-left:0;margin:12px 0;counter-reset:lv}
.levels li{counter-increment:lv;position:relative;padding:9px 14px 9px 44px;background:var(--bg-soft);border:1px solid var(--border);border-radius:10px;margin-bottom:7px;font-size:14px}
.levels li::before{content:counter(lv);position:absolute;left:14px;top:9px;font-family:var(--font-mono);font-weight:700;color:var(--theme)}
.levels li b{font-family:var(--font-mono);font-size:13.5px}

/* quiz */
.quiz label{display:block;background:var(--bg-soft);border:1px solid var(--border);border-radius:10px;padding:10px 14px;margin-bottom:8px;cursor:pointer;font-size:14px}
.quiz label:hover{border-color:var(--theme)}
.quiz input{margin-right:8px}

/* expnav */
.expnav{display:flex;justify-content:space-between;gap:14px;margin-top:30px}
.expnav a{flex:1;background:var(--bg-card);border:1px solid var(--border);border-radius:14px;padding:16px 20px;color:var(--head);font-size:14px;transition:.2s}
.expnav a:hover{border-color:var(--theme);box-shadow:0 6px 18px rgba(0,0,0,.06);text-decoration:none}
.expnav a .lb{display:block;font-size:11.5px;color:var(--muted);letter-spacing:.08em;margin-bottom:4px}
.expnav a.next{text-align:right}

footer{border-top:1px solid var(--border);margin-top:44px;padding-top:22px;font-size:13px;color:var(--muted);display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px}

@media(max-width:960px){.wrap{grid-template-columns:1fr}.side{display:none}.content{padding:24px 18px 70px}}