/* ============================================================
 * lab2.css — 神经网络实验室 v2
 * 视觉定位：深色、安静、克制的实验工作台
 * 单一强调色（蓝）；绿/橙/红只表示状态，不做装饰
 * ============================================================ */
* { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --l2-bg: #0b0c0f;
  --l2-panel: #14161b;
  --l2-card: #14161b;
  --l2-border: #252832;
  --l2-text: #f5f5f7;
  --l2-mute: #8b8f98;
  --l2-accent: #5e7cff;
  --l2-ok: #30d158;
  --l2-warn: #ff9f0a;
  --l2-bad: #f0564f;
}
html[data-theme="light"] {
  --l2-bg: #f5f6f8;
  --l2-panel: #ffffff;
  --l2-card: #ffffff;
  --l2-border: #e2e4ea;
  --l2-text: #1a1c22;
  --l2-mute: #6b6f7c;
}
body { background: var(--l2-bg); color: var(--l2-text); font-family: -apple-system, 'Segoe UI', 'Microsoft YaHei', sans-serif; font-size: 14.5px; }

/* ---------- 顶栏：返回 · 标题 · 进度点 · 站号 · 代码按钮 ---------- */
.lab2-topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; gap: 16px;
  padding: 0 20px; height: 52px;
  background: color-mix(in srgb, var(--l2-bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--l2-border);
}
.lab2-back { color: var(--l2-mute); text-decoration: none; font-size: 15px; flex: none; padding: 4px 8px; border-radius: 8px; }
.lab2-back:hover { color: var(--l2-text); background: var(--l2-panel); }
.lab2-title { font-size: 13.5px; font-weight: 600; flex: none; letter-spacing: .02em; }
/* ---------- 站点导航：并入顶栏居中（上一章 · 点阵（已学点亮） · 下一章） ---------- */
.station-nav {
  position: absolute; left: 50%; transform: translateX(-50%);
  display: flex; align-items: center; justify-content: center;
  gap: 14px; padding: 0; max-width: none; min-width: 0;
}
.nav-jump {
  flex: none; max-width: 120px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
  background: transparent; border: 1px solid var(--l2-border); color: var(--l2-mute);
  font-size: 11.5px; padding: 5px 12px; border-radius: 999px; cursor: pointer;
  transition: color .15s, border-color .15s;
}
.nav-jump:hover:not(:disabled) { color: var(--l2-accent); border-color: var(--l2-accent); }
.nav-jump:disabled { opacity: .3; cursor: default; }
.nav-center { display: flex; flex-direction: row; align-items: center; gap: 10px; }
.nav-dots { display: flex; align-items: center; gap: 10px; }
.chain-node { display: inline-flex; align-items: center; cursor: pointer; padding: 4px 0; }
.chain-dot { width: 7px; height: 7px; border-radius: 50%; transition: all .2s; }
/* 位置规则：当前章及之前点亮，之后灰暗 */
.chain-node.lit .chain-dot { background: var(--l2-accent); }
.chain-node.current .chain-dot { background: var(--l2-accent); transform: scale(1.5); box-shadow: 0 0 0 3px color-mix(in srgb, var(--l2-accent) 25%, transparent); }
.chain-node.after .chain-dot { background: transparent; box-shadow: inset 0 0 0 1.5px var(--l2-border); opacity: .6; }
.chain-node:not(.current):hover .chain-dot { transform: scale(1.3); opacity: 1; }
.nav-cur { font-size: 12px; color: var(--l2-mute); font-variant-numeric: tabular-nums; white-space: nowrap; }
.flow-wrap { max-width: 860px; margin: 0 auto; padding: 14px 24px 0; }
.flow-bar { display: flex; flex-wrap: wrap; gap: 2px 0; align-items: center; }
.flow-node { font-size: 11.5px; padding: 2px 7px; border-radius: 6px; cursor: pointer; background: transparent; border: none; color: var(--l2-mute); }
.flow-node.active { color: var(--l2-accent); font-weight: 600; }
.flow-node.dim { opacity: .35; }
.flow-node:hover { color: var(--l2-text); }
.flow-sep { font-size: 10px; color: var(--l2-border); }

/* ---------- 主列：单列工作台 ---------- */
.lab2-main { max-width: 860px; margin: 0 auto; padding: 10px 24px 60px; }

/* ---------- 步骤头：眉题 · 标题 · 一句话问题 · 任务行 ---------- */
.step-head { padding: 18px 0 6px; }
.step-eyebrow { font-size: 12px; color: var(--l2-mute); letter-spacing: .12em; margin-bottom: 10px; font-variant-numeric: tabular-nums; }
.step-title { font-size: 30px; font-weight: 600; letter-spacing: -0.015em; line-height: 1.3; margin-bottom: 16px; }
.step-lead { font-size: 15.5px; line-height: 1.9; color: var(--l2-text); margin-bottom: 10px; }
.step-task { font-size: 13.5px; line-height: 1.8; color: var(--l2-mute); margin-bottom: 8px; }
.step-task .st-mark { color: var(--l2-warn); margin-right: 8px; font-size: 12px; }
.chain-more { margin: 6px 0 2px; }
.chain-more summary { font-size: 12.5px; color: var(--l2-mute); cursor: pointer; list-style: none; }
.chain-more summary::before { content: '⌄ '; }
.chain-more[open] summary::before { content: '⌃ '; }
.chain-more summary:hover { color: var(--l2-text); }
.chain-more p { font-size: 13px; line-height: 1.9; color: var(--l2-mute); margin-top: 8px; padding-left: 12px; border-left: 2px solid var(--l2-border); }
.chain-more p span { display: block; font-size: 11px; letter-spacing: .08em; color: var(--l2-accent); margin-bottom: 1px; }
/* 兜底：无 chain 数据的旧式 why 列表 */
.step-why { border-top: 1px solid var(--l2-border); padding-top: 12px; }
.why-h { font-size: 11px; font-weight: 600; color: var(--l2-mute); letter-spacing: .08em; margin-bottom: 8px; }
.step-why ul { list-style: none; }
.step-why li { font-size: 13px; color: var(--l2-mute); padding: 2px 0 2px 16px; position: relative; }
.step-why li::before { content: '·'; position: absolute; left: 2px; color: var(--l2-mute); }

/* ---------- 步骤主体 ---------- */
.step-body { display: flex; flex-direction: column; gap: 26px; padding-top: 10px; }
.step-finish { margin-top: 28px; display: flex; justify-content: flex-end; }
.finish-btn { background: var(--l2-accent); color: #fff; border: none; padding: 12px 28px; border-radius: 10px; font-size: 14px; font-weight: 600; cursor: pointer; }
.finish-btn:hover { filter: brightness(1.1); }
.locked-hint { border: 1px dashed var(--l2-border); border-radius: 14px; padding: 48px; text-align: center; color: var(--l2-mute); }

/* ---------- 正文：无边框纯排版 ---------- */
.narrative { font-size: 14.5px; line-height: 1.9; color: var(--l2-text); }
.narrative b { font-weight: 600; color: var(--l2-text); }
.narrative code { font-family: ui-monospace, monospace; font-size: 12.5px; background: var(--l2-panel); padding: 1px 6px; border-radius: 5px; }

/* ---------- 实验舞台：页面的视觉中心 ---------- */
.exp-box, .exp-row {
  background: var(--l2-panel);
  border: 1px solid var(--l2-border);
  border-radius: 16px;
  padding: 24px;
}
.exp-row { display: flex; gap: 28px; align-items: flex-start; }
.exp-col { flex: 1; min-width: 0; }
.exp-h { font-size: 11px; font-weight: 600; color: var(--l2-mute); letter-spacing: .1em; margin-bottom: 16px; }
.exp-note { font-size: 13px; line-height: 1.8; color: var(--l2-mute); margin-top: 12px; }
.exp-note b { color: var(--l2-text); font-weight: 600; }
.math-box { background: transparent; border: none; border-top: 1px solid var(--l2-border); border-radius: 0; padding: 14px 2px 0; margin-top: 16px; display: flex; align-items: baseline; gap: 16px; }
.math-box code { font-family: ui-monospace, monospace; font-size: 15px; color: var(--l2-accent); font-weight: 600; }
.math-box span { font-size: 12.5px; color: var(--l2-mute); }

/* ---------- 预测：安静的提问卡 ---------- */
.predict-box { background: var(--l2-panel); border: 1px solid var(--l2-border); border-radius: 14px; padding: 18px 20px; }
.predict-q { font-size: 14.5px; font-weight: 600; margin-bottom: 12px; }
.predict-opts { display: flex; flex-direction: column; gap: 7px; }
.predict-opt { text-align: left; background: transparent; border: 1px solid var(--l2-border); color: var(--l2-text); font-size: 13.5px; padding: 10px 14px; border-radius: 9px; cursor: pointer; transition: border-color .15s; }
.predict-opt:hover:not(:disabled) { border-color: var(--l2-accent); }
.predict-opt.correct { border-color: var(--l2-ok); background: color-mix(in srgb, var(--l2-ok) 8%, transparent); }
.predict-opt:disabled { cursor: default; opacity: .7; }
.predict-result { margin-top: 12px; font-size: 13px; line-height: 1.7; padding: 10px 14px; border-radius: 9px; }
.predict-result.right { background: color-mix(in srgb, var(--l2-ok) 10%, transparent); color: var(--l2-ok); }
.predict-result.wrong { background: color-mix(in srgb, var(--l2-warn) 10%, transparent); color: var(--l2-warn); }

/* ---------- 失败实验：唯一的红色时刻 ---------- */
.fail-box { background: color-mix(in srgb, var(--l2-bad) 5%, var(--l2-panel)); border: 1px dashed color-mix(in srgb, var(--l2-bad) 55%, var(--l2-border)); border-radius: 14px; padding: 16px 20px; }
.fail-toggle { display: flex; align-items: center; gap: 10px; cursor: pointer; font-size: 13.5px; font-weight: 600; }
.fail-toggle input { width: 16px; height: 16px; accent-color: var(--l2-bad); }
.fail-result { margin-top: 10px; font-size: 13px; line-height: 1.8; color: var(--l2-text); }

/* ---------- 滑杆 ---------- */
.slider-row { margin: 10px 0; }
.slider-row label { font-size: 13px; color: var(--l2-mute); display: flex; justify-content: space-between; margin-bottom: 6px; }
.slider-row .sv { color: var(--l2-accent); }
.slider-row input[type=range] { width: 100%; accent-color: var(--l2-accent); }

/* ---------- 可视化元素 ---------- */
.px-canvas-wrap { position: relative; display: inline-block; }
.px-hl { position: absolute; display: none; border: 2px solid var(--l2-accent); pointer-events: none; z-index: 2; }
.px-canvas { border: 1px solid var(--l2-border); border-radius: 8px; display: block; cursor: crosshair; }
.px-num-grid { display: grid; gap: 1px; max-width: 300px; }
.px-num { aspect-ratio: 1; display: flex; align-items: center; justify-content: center; font-size: 6px; color: rgba(255,255,255,.75); border-radius: 1px; cursor: crosshair; }
.px-num.px-hot { outline: 2px solid var(--l2-accent); outline-offset: -1px; }
.px-readout { margin-top: 12px; font-size: 12.5px; color: var(--l2-mute); min-height: 20px; }
.px-readout b { color: var(--l2-text); }
.avg-row { display: flex; align-items: center; gap: 8px; margin-bottom: 5px; font-size: 12px; }
.avg-row > span:first-child { width: 12px; color: var(--l2-mute); }
.avg-track { flex: 1; height: 14px; background: color-mix(in srgb, var(--l2-border) 45%, transparent); border-radius: 4px; overflow: hidden; }
.avg-fill { height: 100%; background: var(--l2-accent); }
.bias-viz { position: relative; height: 44px; background: color-mix(in srgb, var(--l2-border) 45%, transparent); border-radius: 9px; overflow: hidden; margin: 8px 0; }
.bias-line { position: absolute; top: 0; bottom: 0; width: 3px; background: var(--l2-accent); transition: left .15s; }
.bias-l, .bias-r { position: absolute; top: 13px; font-size: 11px; color: var(--l2-mute); }
.bias-l { left: 10px; } .bias-r { right: 10px; }

/* ---------- 任务/口试卡：弱化为左侧一道发丝线 ---------- */
.task-card { border: none; border-left: 2px solid var(--l2-accent); border-radius: 0 10px 10px 0; padding: 6px 0 6px 16px; margin: 6px 0; background: transparent; display: flex; flex-direction: column; gap: 10px; }
.task-card .tc-h { font-size: 11px; font-weight: 600; color: var(--l2-mute); letter-spacing: .1em; }
.task-card .tc-sec p { font-size: 13.5px; line-height: 1.9; color: var(--l2-text); }
.task-card code { background: var(--l2-panel); border-radius: 5px; padding: 1px 6px; font-size: 12.5px; }
.task-card details { border: none; border-top: 1px solid var(--l2-border); border-radius: 0; padding: 10px 2px; background: transparent; }
.task-card details summary { cursor: pointer; font-size: 13px; font-weight: 600; color: var(--l2-text); }
.task-card .oral-a { margin-top: 8px; font-size: 13px; line-height: 1.8; color: var(--l2-mute); }

/* ---------- 站5 权重图网格 ---------- */
.hidden-grid { display: grid; grid-template-columns: repeat(8, 56px); gap: 6px; }
.hidden-cell { border-radius: 6px; cursor: pointer; transition: transform .12s; }
.hidden-cell:hover { transform: scale(1.06); }

/* ---------- 站尾 THINK ---------- */
.chain-check { margin-top: 6px; border: 1px solid var(--l2-border); border-radius: 16px; padding: 36px 32px; background: var(--l2-panel); text-align: center; }
.chain-check .cc-eyebrow { font-size: 11px; font-weight: 600; color: var(--l2-accent); letter-spacing: .22em; margin-bottom: 16px; }
.chain-check .cc-q { font-size: 17.5px; font-weight: 600; line-height: 1.75; margin-bottom: 20px; max-width: 560px; margin-left: auto; margin-right: auto; }
.chain-check .cc-btn { background: transparent; border: 1px solid var(--l2-border); color: var(--l2-mute); border-radius: 999px; padding: 9px 22px; font-size: 12.5px; cursor: pointer; transition: all .15s; }
.chain-check .cc-btn:hover { border-color: var(--l2-accent); color: var(--l2-accent); }
.chain-check .cc-a { font-size: 14px; line-height: 1.9; margin-top: 18px; color: var(--l2-text); text-align: left; max-width: 560px; margin-left: auto; margin-right: auto; }
.chain-check .cc-next { margin-top: 10px; color: var(--l2-accent); }

/* ---------- 弹层 ---------- */
.wv-overlay { position: fixed; inset: 0; background: rgba(0,0,0,.7); display: flex; align-items: center; justify-content: center; z-index: 999; }
.wv-card { background: var(--l2-panel); border: 1px solid var(--l2-border); border-radius: 16px; padding: 24px 28px; max-width: 580px; text-align: center; }
.wv-title { font-size: 15px; font-weight: 600; margin-bottom: 16px; }
.wv-row { display: flex; gap: 16px; justify-content: center; margin-bottom: 14px; flex-wrap: wrap; }
.wv-row canvas { border-radius: 8px; border: 1px solid var(--l2-border); width: 224px; height: 224px; image-rendering: pixelated; }
.wv-detail { margin: 2px 0 8px; font-size: 13px; color: var(--l2-text); background: rgba(79,110,247,.08); border: 1px solid rgba(79,110,247,.25); border-radius: 8px; padding: 8px 10px; min-height: 22px; }
.wv-chain { margin: 0 0 10px; font-size: 13px; color: var(--l2-text); background: rgba(255,159,10,.07); border: 1px solid rgba(255,159,10,.28); border-radius: 8px; padding: 8px 10px; }
.wv-note { font-size: 13px; color: var(--l2-mute); line-height: 1.8; margin-bottom: 16px; }
.wv-close { min-width: 88px; }

/* ---------- 控件 ---------- */
.seg-row { display: flex; gap: 6px; margin-bottom: 12px; flex-wrap: wrap; }
.seg { background: transparent; border: 1px solid var(--l2-border); color: var(--l2-mute); padding: 5px 13px; border-radius: 8px; font-size: 12px; cursor: pointer; }
.seg.active { border-color: var(--l2-accent); color: var(--l2-accent); background: color-mix(in srgb, var(--l2-accent) 8%, transparent); }
.seg:hover { color: var(--l2-text); }
.fwd-stage { display: flex; flex-direction: column; gap: 16px; align-items: flex-start; }
.fwd-below { display: flex; gap: 24px; align-items: flex-start; flex-wrap: wrap; }
.fwd-below .exp-col { min-width: 260px; }
.fwd-step { font-size: 13px; font-family: inherit; background: transparent; border: none; border-left: 2px solid var(--l2-accent); border-radius: 0; padding: 2px 0 2px 14px; margin-bottom: 14px; color: var(--l2-text); line-height: 1.8; }
.fwd-step .fwd-tag { font-size: 10.5px; color: var(--l2-accent); letter-spacing: .12em; }
.prob-bars { display: flex; flex-direction: column; gap: 4px; }
.pb-row { display: flex; align-items: center; gap: 8px; font-size: 12px; }
.pb-row.win { font-weight: 700; }
.pb-row.win .pb-val { color: var(--l2-accent); }
.pb-row > span:first-child { width: 10px; color: var(--l2-mute); }
.pb-track { flex: 1; height: 12px; background: color-mix(in srgb, var(--l2-border) 45%, transparent); border-radius: 4px; overflow: hidden; }
.pb-fill { height: 100%; background: var(--l2-mute); }
.pb-row.win .pb-fill { background: var(--l2-accent); }
.pb-val { width: 42px; text-align: right; color: var(--l2-mute); }
.pred-grid { display: grid; grid-template-columns: repeat(10, 1fr); gap: 6px; }
.pred-cell { aspect-ratio: 1; border-radius: 8px; display: flex; flex-direction: column; align-items: center; justify-content: center; font-size: 12px; }
.pred-cell.ok { background: color-mix(in srgb, var(--l2-ok) 13%, transparent); color: var(--l2-ok); }
.pred-cell.bad { background: color-mix(in srgb, var(--l2-bad) 13%, transparent); color: var(--l2-bad); }
.pp { font-size: 10px; opacity: .7; }
.avg-bars { margin-bottom: 6px; }
.lab-btn { background: var(--l2-accent); color: #fff; border: none; padding: 9px 20px; border-radius: 9px; font-size: 13px; font-weight: 600; cursor: pointer; }
.lab-btn:hover { filter: brightness(1.12); }
.lab-btn:disabled { opacity: .4; cursor: default; }
.lab-btn.ghost { background: transparent; border: 1px solid var(--l2-border); color: var(--l2-text); }
.loss-chart { background: var(--l2-bg); border: 1px solid var(--l2-border); border-radius: 12px; }
.lr-charts { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-bottom: 8px; }

.finale-flow { font-family: ui-monospace, monospace; font-size: 12px; line-height: 2; color: var(--l2-accent); margin-bottom: 12px; white-space: pre-wrap; }

/* ---------- 数据流检查器（右侧抽屉） ---------- */
.inspector { position: fixed; right: -340px; top: 0; bottom: 0; width: 320px; background: var(--l2-panel); border-left: 1px solid var(--l2-border); z-index: 100; transition: right .25s; padding: 24px; overflow-y: auto; }
.inspector.open { right: 0; }
.insp-close { position: absolute; top: 12px; right: 14px; background: none; border: none; color: var(--l2-mute); font-size: 16px; cursor: pointer; }
.insp-title { font-size: 17px; font-weight: 600; margin-bottom: 18px; color: var(--l2-accent); }
.insp-sec { margin-bottom: 18px; }
.insp-h { font-size: 11px; font-weight: 600; color: var(--l2-mute); letter-spacing: .08em; margin-bottom: 5px; }
.insp-sec p { font-size: 13px; line-height: 1.8; }


/* ---------- 响应式 ---------- */
@media (max-width: 734px) {
  html, body { overflow-x: hidden; }
  .lab2-topbar { gap: 10px; padding: 0 14px; }
  .lab2-title { display: none; }
  .station-nav { gap: 8px; }
  .nav-cur { display: none; }
  .nav-jump { max-width: 92px; font-size: 11px; padding: 4px 10px; }
  .nav-dots { gap: 7px; }
  .flow-wrap { padding: 12px 14px 0; }
  .lab2-main { padding: 6px 14px 48px; }
  .step-title { font-size: 24px; }
  .chain-check { padding: 26px 18px; }
  .exp-box, .exp-row { padding: 16px; }
  .exp-row, .fwd-stage { flex-direction: column; gap: 14px; }
  .math-box { flex-direction: column; align-items: flex-start; gap: 6px; }
  .hidden-grid { grid-template-columns: repeat(8, minmax(0, 1fr)); max-width: 300px; }
  .px-num-grid { max-width: 240px; }
  .lr-charts { grid-template-columns: 1fr; }
  .step-finish { justify-content: stretch; }
  .step-finish .finish-btn { width: 100%; min-height: 46px; }
  .lab-btn { min-height: 44px; }
  .predict-opt { padding: 12px 14px; }
  .wv-row { flex-direction: column; align-items: center; }
}