@import url('https://fonts.googleapis.com/css2?family=Crimson+Pro:ital,wght@0,300;0,400;0,600;0,700;1,400&family=DM+Sans:ital,wght@0,400;0,500;0,600;0,700;1,400&family=JetBrains+Mono:wght@400;500&display=swap');

:root{
  --c-bg:#f8f6f1;
  --c-bg-alt:#efeade;
  --c-surface:#fff;
  --c-surface-alt:#f3f0e8;
  --c-ink:#1a1a1a;
  --c-ink-light:#555;
  --c-ink-muted:#888;
  --c-accent:#276DC3;            /* R 藍 */
  --c-accent-light:#E1EAF4;
  --c-accent-dark:#113055;
  --c-accent2:#2a8a78;            /* 補色 teal */
  --c-highlight:#BEC2C6;
  --c-highlight-light:#EAEBEB;
  --c-danger:#c0392b;
  --c-danger-light:#fde8e5;
  --c-code-bg:#1e293b;
  --c-code-text:#e2e8f0;
  --c-border:#d5cfc0;
  --c-border-light:#e8e3d6;
  --font-display:'Crimson Pro',Georgia,serif;
  --font-body:'DM Sans',-apple-system,sans-serif;
  --font-mono:'JetBrains Mono','Fira Code',monospace;
  --radius:8px;
  --radius-lg:14px;
  --shadow-sm:0 1px 3px rgba(0,0,0,.06);
  --shadow-md:0 4px 16px rgba(0,0,0,.08);
  --shadow-lg:0 8px 32px rgba(0,0,0,.1);
  --max-w:880px;
  --transition:.3s cubic-bezier(.4,0,.2,1);
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:var(--font-body);background:var(--c-bg);color:var(--c-ink);line-height:1.75;-webkit-font-smoothing:antialiased}

/* ---------- Top nav ---------- */
.top-nav{position:sticky;top:0;z-index:100;background:rgba(248,246,241,.92);backdrop-filter:blur(12px);border-bottom:1px solid var(--c-border-light);padding:0 24px}
.top-nav-inner{max-width:1200px;margin:0 auto;display:flex;align-items:center;justify-content:space-between;height:56px;gap:8px}
.top-nav-brand{font-family:var(--font-display);font-size:1.1rem;font-weight:600;color:var(--c-accent-dark);text-decoration:none;display:flex;align-items:center;gap:8px;white-space:nowrap}
.top-nav-brand span{font-size:1.3rem}
.top-nav-links{display:flex;gap:2px;list-style:none;overflow-x:auto;flex:1;justify-content:center;padding:0 8px}
.top-nav-links a{display:block;padding:6px 8px;font-size:.74rem;font-weight:500;color:var(--c-ink-light);text-decoration:none;border-radius:6px;white-space:nowrap;transition:var(--transition)}
.top-nav-links a:hover,.top-nav-links a.active{background:var(--c-accent-light);color:var(--c-accent-dark)}
.lang-toggle{background:var(--c-accent);color:#fff;border:none;border-radius:6px;padding:6px 14px;font-family:var(--font-body);font-size:.82rem;font-weight:700;cursor:pointer;white-space:nowrap;transition:var(--transition);flex-shrink:0}
.lang-toggle:hover{background:var(--c-accent-dark)}

/* ---------- Progress bar ---------- */
.progress-bar-container{position:fixed;top:56px;left:0;width:100%;height:3px;background:var(--c-border-light);z-index:99}
.progress-bar{height:100%;background:linear-gradient(90deg,var(--c-accent),var(--c-highlight));width:0%;transition:width .15s ease}

/* ---------- Hero ---------- */
.page-hero{position:relative;padding:80px 24px 60px;text-align:center;background:linear-gradient(160deg,#113055 0%,#276DC3 40%,#2972CC 100%);color:#fff;overflow:hidden}
.page-hero::before{content:'';position:absolute;top:-50%;right:-20%;width:600px;height:600px;background:radial-gradient(circle,rgba(212,160,60,.15) 0%,transparent 70%);pointer-events:none}
.page-hero .step-badge{display:inline-block;padding:4px 16px;background:rgba(255,255,255,.15);border:1px solid rgba(255,255,255,.25);border-radius:20px;font-size:.82rem;font-weight:600;letter-spacing:.5px;margin-bottom:16px}
.page-hero h1{font-family:var(--font-display);font-size:clamp(2rem,4.5vw,3rem);font-weight:700;line-height:1.2;margin-bottom:12px}
.page-hero .subtitle{font-size:1.05rem;opacity:.9;max-width:660px;margin:0 auto;line-height:1.6}

/* ---------- Hub hero ---------- */
.hub-hero{padding:100px 24px 80px;text-align:center;background:linear-gradient(160deg,#0F2B4C 0%,#276DC3 30%,#337CD6 60%,#6AA0E1 100%);color:#fff;position:relative;overflow:hidden}
.hub-hero::after{content:'';position:absolute;bottom:-2px;left:0;right:0;height:60px;background:var(--c-bg);clip-path:ellipse(52% 100% at 50% 100%)}
.hub-hero h1{font-family:var(--font-display);font-size:clamp(2.5rem,5vw,3.5rem);font-weight:700;margin-bottom:16px}
.hub-hero p{font-size:1.1rem;opacity:.9;max-width:620px;margin:0 auto}

/* ---------- Content ---------- */
.content-wrap{max-width:var(--max-w);margin:0 auto;padding:48px 24px 80px}
.section{margin-bottom:56px;animation:fadeUp .5s ease both}
@keyframes fadeUp{from{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}
.section-label{display:inline-flex;align-items:center;gap:6px;font-size:.75rem;font-weight:700;text-transform:uppercase;letter-spacing:1.5px;color:var(--c-accent);margin-bottom:8px}
.section-label::before{content:'';width:18px;height:2px;background:var(--c-accent)}
.section h2{font-family:var(--font-display);font-size:1.75rem;font-weight:700;color:var(--c-ink);margin-bottom:16px;line-height:1.3}
.section h3{font-family:var(--font-display);font-size:1.3rem;font-weight:600;margin-top:32px;margin-bottom:12px}
.section h4{font-family:var(--font-display);font-size:1.1rem;font-weight:600;margin-top:20px;margin-bottom:8px}
.section p{color:var(--c-ink-light);margin-bottom:16px}
.section p strong{color:var(--c-ink);font-weight:600}
.section ul, .section ol{margin:0 0 16px 24px;color:var(--c-ink-light)}
.section li{margin-bottom:6px}
.section li strong{color:var(--c-ink)}

/* ---------- Cards ---------- */
.card{background:var(--c-surface);border:1px solid var(--c-border-light);border-radius:var(--radius-lg);padding:24px;margin-bottom:18px;box-shadow:var(--shadow-sm);transition:var(--transition)}
.card:hover{box-shadow:var(--shadow-md);border-color:var(--c-border)}
.card-grid{display:grid;gap:14px}
.card-grid.cols-2{grid-template-columns:repeat(auto-fit,minmax(280px,1fr))}
.card-grid.cols-3{grid-template-columns:repeat(auto-fit,minmax(220px,1fr))}
.card-icon{width:46px;height:46px;display:flex;align-items:center;justify-content:center;font-size:1.5rem;background:var(--c-accent-light);border-radius:12px;margin-bottom:12px}
.card h4{font-family:var(--font-display);font-size:1.05rem;font-weight:600;margin-bottom:6px;margin-top:0}
.card p{font-size:.92rem;color:var(--c-ink-light);margin-bottom:0}

/* ---------- Term tooltip ---------- */
.term{position:relative;font-weight:600;color:var(--c-accent-dark);border-bottom:1.5px dotted var(--c-accent);cursor:help}
.term .term-tip{display:none;position:absolute;bottom:100%;left:50%;transform:translateX(-50%);background:var(--c-code-bg);color:var(--c-code-text);padding:8px 14px;border-radius:8px;font-size:.82rem;font-weight:400;max-width:320px;white-space:normal;z-index:50;box-shadow:var(--shadow-lg);pointer-events:none;margin-bottom:6px;text-align:left}
.term:hover .term-tip{display:block}

/* ---------- Code blocks & tabs ---------- */
.code-tabs{background:var(--c-code-bg);border-radius:var(--radius-lg);overflow:hidden;margin:20px 0;box-shadow:var(--shadow-md)}
.code-tab-btns{display:flex;background:rgba(0,0,0,.25);padding:0 12px;gap:2px;align-items:center}
.code-tab-btns .code-tab-btn{padding:10px 18px;background:none;border:none;color:rgba(255,255,255,.5);font-family:var(--font-mono);font-size:.8rem;cursor:pointer;border-bottom:2px solid transparent;transition:var(--transition)}
.code-tab-btns .code-tab-btn.active{color:#fff;border-bottom-color:var(--c-highlight)}
.code-tab-btns .code-copy{margin-left:auto;background:none;border:none;color:rgba(255,255,255,.55);font-family:var(--font-mono);font-size:.72rem;cursor:pointer;padding:4px 10px;border-radius:4px;transition:var(--transition)}
.code-tab-btns .code-copy:hover{color:#fff;background:rgba(255,255,255,.1)}
.code-tab-content{display:none;padding:18px 20px;overflow-x:auto}
.code-tab-content.active{display:block}
.code-tab-content pre{margin:0;font-family:var(--font-mono);font-size:.84rem;line-height:1.65;color:var(--c-code-text);white-space:pre}
.comment{color:#7a9c8b}.func{color:#7dd3fc}.str{color:#fcd34d}.kw{color:#c084fc}.num{color:#f9a8d4}.op{color:#f59e0b}

/* code block standalone */
pre.code{background:var(--c-code-bg);color:var(--c-code-text);padding:18px 20px;border-radius:var(--radius-lg);overflow-x:auto;font-family:var(--font-mono);font-size:.84rem;line-height:1.65;margin:16px 0}
code.inline{background:var(--c-bg-alt);color:var(--c-accent-dark);padding:1px 6px;border-radius:4px;font-family:var(--font-mono);font-size:.86em}

/* ---------- WebR runner ---------- */
.webr-block{background:var(--c-code-bg);border-radius:var(--radius-lg);overflow:hidden;margin:20px 0;box-shadow:var(--shadow-md);border:1px solid #334155}
.webr-header{display:flex;align-items:center;justify-content:space-between;padding:8px 14px;background:rgba(0,0,0,.3);border-bottom:1px solid rgba(255,255,255,.05)}
.webr-header .webr-title{color:#94a3b8;font-family:var(--font-mono);font-size:.78rem}
.webr-header .webr-title::before{content:'⚡ ';color:var(--c-highlight)}
.webr-run{background:var(--c-highlight);color:#1a1a1a;border:none;border-radius:6px;padding:6px 14px;font-family:var(--font-body);font-size:.78rem;font-weight:700;cursor:pointer;transition:var(--transition)}
.webr-run:hover{background:#e6b450;transform:translateY(-1px)}
.webr-run:disabled{opacity:.5;cursor:wait}
.webr-editor{width:100%;padding:14px 18px;border:none;background:transparent;color:var(--c-code-text);font-family:var(--font-mono);font-size:.84rem;line-height:1.65;resize:vertical;min-height:90px;outline:none;white-space:pre;tab-size:2}
.webr-output{margin:0;padding:12px 18px;font-family:var(--font-mono);font-size:.8rem;line-height:1.55;color:#a5d8c6;background:rgba(0,0,0,.25);border-top:1px solid rgba(255,255,255,.05);max-height:280px;overflow:auto;white-space:pre-wrap;word-break:break-word;display:none}
.webr-output.show{display:block}
.webr-output.error{color:#fca5a5}
.webr-output img{max-width:100%;border-radius:6px;background:#fff;padding:6px;margin-top:6px}
.webr-status{padding:6px 18px;font-family:var(--font-mono);font-size:.72rem;color:#94a3b8;background:rgba(0,0,0,.25);border-top:1px solid rgba(255,255,255,.05);display:none}
.webr-status.show{display:block}

/* ---------- Interactive sim ---------- */
.interactive-panel{background:var(--c-surface);border:2px solid var(--c-accent);border-radius:var(--radius-lg);padding:28px;margin:28px 0;position:relative}
.interactive-panel::before{content:'⚡ 互動';position:absolute;top:-12px;left:20px;background:var(--c-accent);color:#fff;padding:2px 14px;border-radius:10px;font-size:.75rem;font-weight:600}
.interactive-panel[data-en]::before{content:attr(data-label-en)}
.slider-group{margin:14px 0}
.slider-group label{display:flex;justify-content:space-between;font-size:.88rem;font-weight:600;margin-bottom:6px;color:var(--c-ink)}
.slider-group label span{color:var(--c-accent);font-family:var(--font-mono)}
input[type=range]{-webkit-appearance:none;appearance:none;width:100%;height:6px;border-radius:3px;background:var(--c-bg-alt);outline:none}
input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:20px;height:20px;border-radius:50%;background:var(--c-accent);cursor:pointer;box-shadow:0 2px 6px rgba(0,0,0,.2)}
input[type=range]::-moz-range-thumb{width:20px;height:20px;border-radius:50%;background:var(--c-accent);cursor:pointer;border:none;box-shadow:0 2px 6px rgba(0,0,0,.2)}
.sim-stats{display:flex;gap:14px;margin:12px 0;flex-wrap:wrap}
.sim-stat{padding:8px 16px;border-radius:8px;font-size:.85rem;font-weight:600}
.sim-stat.pass{background:var(--c-accent-light);color:var(--c-accent-dark)}
.sim-stat.fail{background:var(--c-danger-light);color:var(--c-danger)}
.sim-stat.info{background:#fff3d8;color:#7a5a16}
.chart-container{position:relative;width:100%;height:360px;background:var(--c-surface-alt);border-radius:var(--radius);margin:16px 0;overflow:hidden}
.chart-container canvas{width:100%!important;height:100%!important}

/* ---------- Decision tree ---------- */
.decision-tree{background:var(--c-highlight-light);border-left:4px solid var(--c-highlight);border-radius:0 var(--radius-lg) var(--radius-lg) 0;padding:24px 28px;margin:24px 0}
.decision-tree h4{font-family:var(--font-display);font-size:1.1rem;color:var(--c-ink);margin-bottom:12px;margin-top:0}
.dt-node{display:flex;align-items:flex-start;gap:12px;padding:8px 0;font-size:.92rem}
.dt-node .dt-q{font-weight:600;color:var(--c-ink);min-width:42px}
.dt-node .dt-arrow{color:var(--c-highlight);font-weight:700}

/* ---------- Comparison table ---------- */
.comp-table{width:100%;border-collapse:collapse;margin:20px 0;font-size:.9rem;background:var(--c-surface);border-radius:var(--radius-lg);overflow:hidden;box-shadow:var(--shadow-sm)}
.comp-table thead{background:var(--c-accent-dark);color:#fff}
.comp-table th{padding:14px 18px;text-align:left;font-weight:600;font-size:.85rem}
.comp-table td{padding:12px 18px;border-bottom:1px solid var(--c-border-light);color:var(--c-ink-light);font-size:.88rem;vertical-align:top}
.comp-table tr:last-child td{border-bottom:none}
.comp-table tr:nth-child(even){background:var(--c-surface-alt)}
.comp-table td code{background:var(--c-bg-alt);padding:1px 5px;border-radius:3px;font-size:.82em;color:var(--c-accent-dark)}

/* ---------- Quiz ---------- */
.quiz-section{background:linear-gradient(135deg,#eef4fb 0%,#fdf8ee 100%);border:1px solid var(--c-border);border-radius:var(--radius-lg);padding:32px;margin:40px 0}
.quiz-section h3{font-family:var(--font-display);font-size:1.2rem;margin-top:0;margin-bottom:20px;color:var(--c-accent-dark)}
.quiz-q{margin-bottom:24px;padding-bottom:24px;border-bottom:1px solid var(--c-border-light)}
.quiz-q:last-child{border-bottom:none;margin-bottom:0;padding-bottom:0}
.quiz-q p{font-weight:600;color:var(--c-ink);margin-bottom:10px}
.quiz-options{display:flex;flex-direction:column;gap:6px}
.quiz-opt{display:flex;align-items:flex-start;gap:10px;padding:10px 16px;background:var(--c-surface);border:1px solid var(--c-border-light);border-radius:8px;cursor:pointer;font-size:.9rem;transition:var(--transition);color:var(--c-ink-light)}
.quiz-opt:hover{border-color:var(--c-accent);background:var(--c-accent-light)}
.quiz-opt.correct{background:#d1fae5;border-color:#059669;color:#064e3b}
.quiz-opt.wrong{background:#fee2e2;border-color:#dc2626;color:#7f1d1d}
.quiz-feedback{margin-top:10px;padding:10px 14px;border-radius:8px;font-size:.88rem;display:none}
.quiz-feedback.show{display:block}
.quiz-feedback.correct-fb{background:#d1fae5;color:#065f46}
.quiz-feedback.wrong-fb{background:#fee2e2;color:#991b1b}

/* ---------- Page nav ---------- */
.page-nav{display:flex;justify-content:space-between;gap:16px;margin-top:64px;padding-top:32px;border-top:1px solid var(--c-border-light)}
.page-nav a{flex:1;display:flex;flex-direction:column;gap:4px;padding:18px 22px;background:var(--c-surface);border:1px solid var(--c-border-light);border-radius:var(--radius-lg);text-decoration:none;transition:var(--transition)}
.page-nav a:hover{border-color:var(--c-accent);box-shadow:var(--shadow-md);transform:translateY(-2px)}
.page-nav a .nav-dir{font-size:.72rem;font-weight:700;text-transform:uppercase;letter-spacing:1px;color:var(--c-accent)}
.page-nav a .nav-title{font-family:var(--font-display);font-size:1.02rem;font-weight:600;color:var(--c-ink)}
.page-nav a:last-child{text-align:right}
.page-nav .placeholder{flex:1}

/* ---------- Callouts ---------- */
.callout{display:flex;gap:14px;padding:18px 22px;border-radius:var(--radius-lg);margin:18px 0;font-size:.92rem;align-items:flex-start}
.callout-icon{font-size:1.3rem;flex-shrink:0;margin-top:2px;line-height:1}
.callout.tip{background:var(--c-accent-light);border-left:4px solid var(--c-accent)}
.callout.warn{background:var(--c-highlight-light);border-left:4px solid var(--c-highlight)}
.callout.danger{background:var(--c-danger-light);border-left:4px solid var(--c-danger)}
.callout strong{color:var(--c-ink)}
.callout code{background:rgba(0,0,0,.06);padding:1px 5px;border-radius:3px;font-family:var(--font-mono);font-size:.86em;color:var(--c-accent-dark)}

/* ---------- Workflow steps ---------- */
.workflow{position:relative;padding-left:36px;margin:20px 0}
.workflow::before{content:'';position:absolute;left:14px;top:4px;bottom:4px;width:2px;background:var(--c-accent);opacity:.3}
.workflow-step{position:relative;padding:0 0 24px 18px}
.workflow-step::before{content:attr(data-step);position:absolute;left:-32px;top:0;width:28px;height:28px;background:var(--c-accent);color:#fff;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:.74rem;font-weight:700}
.workflow-step h4{font-size:1rem;margin-bottom:4px;margin-top:0;color:var(--c-ink)}
.workflow-step p{margin-bottom:6px;font-size:.93rem}

/* ---------- Accordion ---------- */
.accordion-item{background:var(--c-surface);border:1px solid var(--c-border-light);border-radius:var(--radius);margin-bottom:8px;overflow:hidden}
.accordion-btn{width:100%;text-align:left;padding:14px 18px;background:none;border:none;font-family:var(--font-body);font-size:.95rem;font-weight:600;color:var(--c-ink);cursor:pointer;display:flex;justify-content:space-between;align-items:center}
.accordion-btn::after{content:'▾';color:var(--c-ink-muted);transition:var(--transition)}
.accordion-btn.open::after{transform:rotate(180deg)}
.accordion-body{padding:0 18px 14px;display:none;font-size:.9rem;color:var(--c-ink-light);line-height:1.7}
.accordion-body.open{display:block}
.accordion-body code{background:var(--c-bg-alt);padding:1px 5px;border-radius:3px;font-family:var(--font-mono);font-size:.86em;color:var(--c-accent-dark)}

/* ---------- Hub cards ---------- */
.hub-steps-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;max-width:1200px;margin:0 auto;padding:0 24px}
.hub-card{display:flex;flex-direction:column;gap:6px;padding:22px;background:var(--c-surface);border:1px solid var(--c-border-light);border-radius:var(--radius-lg);text-decoration:none;color:var(--c-ink);box-shadow:var(--shadow-sm);transition:var(--transition);overflow:hidden}
.hub-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:var(--c-accent)}
.hub-card .step-num{font-size:.7rem;font-weight:700;letter-spacing:1px;text-transform:uppercase;color:var(--c-accent)}
.hub-card h3{font-family:var(--font-display);font-size:1.1rem;font-weight:600;margin:0;color:var(--c-ink)}
.hub-card p{font-size:.85rem;color:var(--c-ink-muted);line-height:1.55;margin:0}
.hub-card .hub-emoji{font-size:1.7rem;margin-bottom:4px}
.hub-section-title{max-width:1200px;margin:48px auto 16px;padding:0 24px;font-family:var(--font-display);font-size:1.4rem;font-weight:600;color:var(--c-ink);display:flex;align-items:baseline;gap:12px}
.hub-section-title span:first-child{color:var(--c-accent);font-size:1.1rem;font-weight:700;font-family:var(--font-mono)}

/* ---------- Toggles & misc ---------- */
.toggle-row{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:14px}
.toggle-btn{background:var(--c-bg-alt);color:var(--c-ink);border:none;border-radius:6px;padding:8px 16px;font-family:var(--font-body);font-size:.86rem;font-weight:600;cursor:pointer;transition:var(--transition)}
.toggle-btn.active{background:var(--c-accent);color:#fff}
.toggle-btn-sm{padding:6px 12px;font-size:.8rem}
.kbd{display:inline-block;padding:2px 7px;font-family:var(--font-mono);font-size:.78rem;background:var(--c-bg-alt);border:1px solid var(--c-border);border-bottom-width:2px;border-radius:4px;color:var(--c-ink);box-shadow:0 1px 0 rgba(0,0,0,.04)}
.path-display{font-family:var(--font-mono);font-size:.86rem;background:var(--c-bg-alt);border-left:3px solid var(--c-accent);padding:8px 14px;border-radius:0 6px 6px 0;color:var(--c-accent-dark);margin:8px 0;display:inline-block;word-break:break-all}

/* ---------- Footer ---------- */
.site-footer{text-align:center;padding:32px 24px;font-size:.82rem;color:var(--c-ink-muted);border-top:1px solid var(--c-border-light)}
.site-footer a{color:var(--c-accent)}

/* ---------- Mobile ---------- */
@media(max-width:768px){
  .top-nav-links{display:none}
  .page-hero{padding:60px 20px 40px}
  .content-wrap{padding:32px 18px 60px}
  .page-nav{flex-direction:column}
  .card-grid.cols-3{grid-template-columns:1fr}
  .comp-table{font-size:.78rem;display:block;overflow-x:auto;white-space:nowrap}
  .comp-table th,.comp-table td{padding:10px 12px}
  .interactive-panel{padding:20px 16px}
  .chart-container{height:280px}
}