/* ============================================
   产品游戏化 — 视觉系统
   ============================================ */

:root {
    --c-bg: #fafaf9; --c-bg-alt: #f5f5f4; --c-card: #ffffff;
    --c-text: #1c1917; --c-text-2: #44403c; --c-text-3: #78716c;
    --c-text-4: #a8a29e; --c-border: #e7e5e4; --c-border-light: #f5f5f4;
    --c-accent: #ea580c; --c-accent-light: #fff7ed; --c-accent-soft: #fdba74;
    --c-green: #15803d; --c-green-light: #f0fdf4; --c-green-soft: #86efac;
    --c-blue: #0369a1; --c-blue-light: #f0f9ff; --c-blue-soft: #7dd3fc;
    --c-purple: #7c3aed; --c-purple-light: #f5f3ff; --c-purple-soft: #c4b5fd;
    --c-red: #dc2626; --c-red-light: #fef2f2;
    --c-yellow: #a16207; --c-yellow-light: #fefce8; --c-yellow-soft: #fde047;
    --c-pink: #be185d; --c-pink-light: #fdf2f8; --c-pink-soft: #f9a8d4;
    --c-teal: #0f766e; --c-teal-light: #f0fdfa; --c-teal-soft: #5eead4;
    --c-indigo: #4338ca; --c-indigo-light: #eef2ff; --c-indigo-soft: #a5b4fc;
    --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
    --s-section: 120px; --s-inner: 720px;
    --r: 12px; --r-lg: 16px; --r-xl: 20px;
    --shadow: 0 1px 3px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.03);
    --shadow-hover: 0 4px 12px rgba(0,0,0,0.06), 0 12px 32px rgba(0,0,0,0.04);
    --ease: cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
    font-family: var(--font); background: var(--c-bg); color: var(--c-text);
    line-height: 1.75; -webkit-font-smoothing: antialiased; overflow-x: hidden;
}
a { color: inherit; text-decoration: none; }

.read-progress {
    position: fixed; top: 0; left: 0; height: 2px;
    background: var(--c-accent); z-index: 10000;
    transition: width 0.1s linear; width: 0%;
}

/* ---- 侧边目录 ---- */
.toc {
    position: fixed; left: 0; top: 0; width: 220px; height: 100vh;
    padding: 32px 20px; z-index: 100; display: none;
}
.toc-inner { position: sticky; top: 32px; }
.toc-title {
    font-size: 11px; font-weight: 700; text-transform: uppercase;
    letter-spacing: 1.5px; color: var(--c-text-4);
    margin-bottom: 16px; padding-left: 12px;
}
.toc-nav { display: flex; flex-direction: column; gap: 2px; }
.toc-link {
    display: block; padding: 6px 12px; border-radius: 6px;
    font-size: 13px; color: var(--c-text-3);
    transition: all 0.2s var(--ease);
    border-left: 2px solid transparent;
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.toc-link:hover { color: var(--c-text); background: var(--c-bg-alt); }
.toc-link.active {
    color: var(--c-accent); background: var(--c-accent-light);
    border-left-color: var(--c-accent); font-weight: 600;
}
@media (min-width: 1100px) { .toc { display: block; } body { padding-left: 220px; } }

/* ============================================
   封面 + Octalysis 预览
   ============================================ */
.cover {
    min-height: 100vh; display: flex; flex-direction: column;
    align-items: center; justify-content: center; text-align: center;
    padding: 80px 24px; position: relative;
    background: linear-gradient(180deg, #fafaf9 0%, #f5f5f4 100%);
}
.cover-inner { max-width: 640px; }
.cover-tag {
    display: inline-block; padding: 5px 16px;
    background: var(--c-accent-light); color: var(--c-accent);
    border-radius: 100px; font-size: 13px; font-weight: 600;
    margin-bottom: 28px; letter-spacing: 0.5px;
}
.cover-title {
    font-size: clamp(2.8rem, 6vw, 4.2rem); font-weight: 900;
    line-height: 1.05; letter-spacing: -0.03em;
    color: var(--c-text); margin-bottom: 16px;
}
.cover-subtitle {
    font-size: 1.15rem; color: var(--c-text-3); line-height: 1.7;
    margin-bottom: 36px; max-width: 480px;
    margin-left: auto; margin-right: auto;
}

/* Octalysis 预览 */
.octalysis-preview {
    max-width: 400px; margin: 0 auto 40px;
    position: relative;
}
.op-center {
    width: 80px; height: 80px; border-radius: 50%;
    background: var(--c-card); border: 2px solid var(--c-accent);
    display: flex; flex-direction: column; align-items: center;
    justify-content: center; gap: 2px;
    margin: 0 auto 16px; box-shadow: var(--shadow);
    animation: centerPulse 3s ease-in-out infinite;
}
@keyframes centerPulse {
    0%, 100% { box-shadow: var(--shadow); }
    50% { box-shadow: 0 0 20px rgba(234, 88, 12, 0.2); }
}
.op-c-icon { font-size: 1.6rem; }
.op-c-text { font-size: 10px; font-weight: 700; color: var(--c-accent); }

.op-items {
    display: grid; grid-template-columns: repeat(4, 1fr);
    gap: 8px;
}
.op-item {
    display: flex; flex-direction: column; align-items: center;
    text-align: center; gap: 2px;
    padding: 12px 8px; background: var(--c-card);
    border: 1.5px solid var(--c-border); border-radius: var(--r-lg);
    box-shadow: var(--shadow); transition: all 0.3s var(--ease);
    cursor: default;
    animation: itemFloat 3s ease-in-out infinite;
}
.op-item:nth-child(1) { animation-delay: 0s; border-color: var(--c-blue-soft); }
.op-item:nth-child(2) { animation-delay: 0.2s; border-color: var(--c-green-soft); }
.op-item:nth-child(3) { animation-delay: 0.4s; border-color: var(--c-yellow-soft); }
.op-item:nth-child(4) { animation-delay: 0.6s; border-color: var(--c-purple-soft); }
.op-item:nth-child(5) { animation-delay: 0.8s; border-color: var(--c-pink-soft); }
.op-item:nth-child(6) { animation-delay: 1s; border-color: var(--c-red-light); }
.op-item:nth-child(7) { animation-delay: 1.2s; border-color: var(--c-teal-soft); }
.op-item:nth-child(8) { animation-delay: 1.4s; border-color: var(--c-indigo-soft); }

@keyframes itemFloat {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-3px); }
}

.op-item:hover { transform: scale(1.05); box-shadow: var(--shadow-hover); }
.op-i-num { font-size: 9px; font-weight: 700; color: var(--c-text-4); }
.op-i-icon { font-size: 1.3rem; }
.op-i-name { font-size: 11px; font-weight: 600; color: var(--c-text); }

.cover-cta {
    display: flex; gap: 12px; justify-content: center;
    flex-wrap: wrap; margin-bottom: 40px;
}
.btn-main {
    display: inline-flex; align-items: center;
    padding: 12px 28px; background: var(--c-text); color: white;
    border-radius: 100px; font-size: 15px; font-weight: 600;
    transition: all 0.25s var(--ease); border: none;
    cursor: pointer; font-family: inherit;
}
.btn-main:hover { background: var(--c-text-2); transform: translateY(-1px); }
.btn-ghost {
    display: inline-flex; align-items: center;
    padding: 12px 28px; background: transparent;
    color: var(--c-text-3); border-radius: 100px;
    font-size: 15px; font-weight: 500;
    transition: all 0.25s var(--ease);
    border: 1.5px solid var(--c-border);
    cursor: pointer; font-family: inherit;
}
.btn-ghost:hover { border-color: var(--c-text-3); color: var(--c-text); }
.cover-meta {
    display: flex; align-items: center; justify-content: center;
    gap: 8px; font-size: 13px; color: var(--c-text-4);
}
.meta-dot { color: var(--c-border); }
.cover-scroll {
    position: absolute; bottom: 32px; left: 50%;
    transform: translateX(-50%); color: var(--c-text-4);
    animation: bounceDown 2s ease-in-out infinite;
}
@keyframes bounceDown {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(8px); }
}

/* ============================================
   章节通用
   ============================================ */
.chapter { padding: var(--s-section) 24px; }
.chapter-alt { background: var(--c-bg-alt); }
.chapter-inner { max-width: var(--s-inner); margin: 0 auto; }
.chapter-num {
    display: block; font-size: 13px; font-weight: 700;
    color: var(--c-accent); text-transform: uppercase;
    letter-spacing: 2px; margin-bottom: 12px;
}
.chapter-title {
    font-size: clamp(1.6rem, 3.5vw, 2.2rem); font-weight: 800;
    line-height: 1.2; letter-spacing: -0.02em;
    margin-bottom: 12px; color: var(--c-text);
}
.chapter-lead {
    font-size: 1.05rem; color: var(--c-text-3); line-height: 1.7;
    margin-bottom: 48px; max-width: 560px;
}

/* ============================================
   01 定义
   ============================================ */
.definition-box {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); padding: 40px; margin-bottom: 40px;
    position: relative; box-shadow: var(--shadow);
}
.def-quote-mark {
    font-family: Georgia, serif; font-size: 4rem; line-height: 1;
    color: var(--c-accent-soft);
    position: absolute; top: 16px; left: 24px;
}
.definition-text {
    font-size: 1.25rem; line-height: 1.7; color: var(--c-text);
    padding-top: 16px; padding-left: 8px;
}
.definition-text strong { color: var(--c-accent); font-weight: 700; }
.definition-by {
    font-size: 14px; color: var(--c-text-4); margin-top: 16px;
    padding-left: 8px;
}

.analogy-box { margin-bottom: 48px; }
.analogy-box h3 {
    font-size: 1rem; font-weight: 700; margin-bottom: 20px;
    color: var(--c-text-2);
}
.analogy-content {
    display: grid; grid-template-columns: 1fr auto 1fr;
    gap: 20px; align-items: center;
}
.analogy-item {
    display: flex; align-items: flex-start; gap: 16px;
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-lg); padding: 24px; box-shadow: var(--shadow);
}
.analogy-icon {
    width: 44px; height: 44px; border-radius: var(--r);
    display: flex; align-items: center; justify-content: center;
    font-size: 1.4rem; flex-shrink: 0;
}
.ai-gray { background: var(--c-bg-alt); }
.ai-accent { background: var(--c-accent-light); }
.analogy-text strong {
    display: block; font-size: 1rem; font-weight: 700;
    color: var(--c-text); margin-bottom: 4px;
}
.analogy-text span {
    font-size: 14px; color: var(--c-text-3); line-height: 1.6;
}
.analogy-vs {
    font-size: 13px; font-weight: 700; color: var(--c-text-4);
    text-transform: uppercase; letter-spacing: 2px;
}

/* ============================================
   02 为什么重要
   ============================================ */
.problems-grid { display: grid; gap: 20px; margin-bottom: 36px; }
.problem-card {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); padding: 32px; box-shadow: var(--shadow);
    transition: all 0.3s var(--ease);
}
.problem-card:hover {
    box-shadow: var(--shadow-hover); transform: translateY(-2px);
}
.problem-num {
    font-size: 13px; font-weight: 700; color: var(--c-accent);
    margin-bottom: 8px; letter-spacing: 1px;
}
.problem-card h3 {
    font-size: 1.15rem; font-weight: 700; margin-bottom: 10px;
    color: var(--c-text);
}
.problem-card > p {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
    margin-bottom: 16px;
}
.problem-card > p strong { color: var(--c-text); }
.problem-example {
    background: var(--c-bg-alt); border-radius: var(--r);
    padding: 14px 18px; font-size: 14px; color: var(--c-text-3);
    line-height: 1.6;
}
.pe-label {
    display: block; font-size: 10px; font-weight: 700;
    text-transform: uppercase; letter-spacing: 1.5px;
    color: var(--c-text-4); margin-bottom: 4px;
}

.insight-banner {
    display: flex; align-items: flex-start; gap: 16px;
    background: var(--c-card); border: 1px solid var(--c-accent-soft);
    border-radius: var(--r-xl); padding: 24px 28px; box-shadow: var(--shadow);
}
.insight-icon { font-size: 1.5rem; flex-shrink: 0; margin-top: 2px; }
.insight-banner p {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
}
.insight-banner strong { color: var(--c-text); }

/* ============================================
   03 八角框架
   ============================================ */
.drive-card {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); padding: 32px; margin-bottom: 20px;
    box-shadow: var(--shadow); transition: all 0.3s var(--ease);
}
.drive-card:hover { box-shadow: var(--shadow-hover); }
.dc-header {
    display: flex; align-items: center; gap: 12px;
    margin-bottom: 16px; padding-bottom: 14px;
    border-bottom: 1px solid var(--c-border-light);
}
.dc-num {
    width: 30px; height: 30px; border-radius: 50%;
    background: var(--c-text); color: white;
    display: flex; align-items: center; justify-content: center;
    font-size: 12px; font-weight: 700; flex-shrink: 0;
}
.dc-icon { font-size: 1.6rem; }
.dc-header h3 { font-size: 1.1rem; font-weight: 700; color: var(--c-text); }
.dc-body > p {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
    margin-bottom: 20px;
}
.dc-body > p strong { color: var(--c-text); }

.dc-examples { display: flex; flex-direction: column; gap: 10px; }
.dc-ex {
    display: flex; flex-direction: column; gap: 2px;
    padding: 14px 18px; background: var(--c-bg-alt);
    border-radius: var(--r-lg); transition: all 0.2s var(--ease);
}
.dc-ex:hover { transform: translateX(4px); background: var(--c-card); box-shadow: var(--shadow); }
.dc-ex > strong { font-size: 14px; color: var(--c-text); }
.dc-ex > span { font-size: 13px; color: var(--c-text-3); line-height: 1.5; }

/* ============================================
   04 案例
   ============================================ */
.case-block {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); overflow: hidden;
    margin-bottom: 24px; box-shadow: var(--shadow);
    transition: all 0.3s var(--ease);
}
.case-block:hover { box-shadow: var(--shadow-hover); }
.case-header {
    padding: 28px 32px; background: var(--c-bg-alt);
    border-bottom: 1px solid var(--c-border-light);
}
.case-badge {
    display: inline-block; padding: 3px 10px;
    background: var(--c-accent-light); color: var(--c-accent);
    border-radius: 100px; font-size: 11px; font-weight: 700;
    text-transform: uppercase; letter-spacing: 1px;
    margin-bottom: 8px;
}
.case-header h3 { font-size: 1.15rem; font-weight: 700; color: var(--c-text); }
.case-body { padding: 28px 32px; }
.case-situation {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
    margin-bottom: 24px; padding-bottom: 20px;
    border-bottom: 1px solid var(--c-border-light);
}
.case-situation strong { color: var(--c-text); }

/* Octalysis 标签 */
.octalysis-tags {
    display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px;
}
.ot {
    display: inline-block; padding: 4px 10px;
    border-radius: 100px; font-size: 11px; font-weight: 700;
}
.ot-social { background: var(--c-blue-light); color: var(--c-blue); }
.ot-achievement { background: var(--c-green-light); color: var(--c-green); }
.ot-ownership { background: var(--c-purple-light); color: var(--c-purple); }
.ot-creative { background: var(--c-yellow-light); color: var(--c-yellow); }
.ot-scarcity { background: var(--c-red-light); color: var(--c-red); }
.ot-unknown { background: var(--c-teal-light); color: var(--c-teal); }
.ot-loss { background: var(--c-indigo-light); color: var(--c-indigo); }

.case-process-flow {
    display: grid; grid-template-columns: repeat(3, 1fr);
    gap: 16px; margin-bottom: 24px;
}
.cpf-step {
    padding: 20px; background: var(--c-bg-alt);
    border-radius: var(--r-lg); transition: all 0.3s var(--ease);
}
.cpf-step:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.cpf-tag {
    display: inline-block; padding: 3px 10px;
    background: var(--c-text); color: white;
    border-radius: 100px; font-size: 10px; font-weight: 700;
    text-transform: uppercase; letter-spacing: 1px;
    margin-bottom: 10px;
}
.cpf-step p { font-size: 14px; color: var(--c-text-2); line-height: 1.6; }
.cpf-step strong { color: var(--c-text); font-size: 13px; }
.case-result-box {
    background: var(--c-green-light); border: 1px solid var(--c-green-soft);
    border-radius: var(--r-lg); padding: 18px 22px;
}
.crb-label {
    display: block; font-size: 11px; font-weight: 700;
    text-transform: uppercase; letter-spacing: 1.5px;
    color: var(--c-green); margin-bottom: 6px;
}
.case-result-box p { font-size: 14px; color: #14532d; line-height: 1.6; }

/* ============================================
   05 练习
   ============================================ */
.practice-scene {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); overflow: hidden;
    margin-bottom: 24px; box-shadow: var(--shadow);
}
.ps-header {
    padding: 24px 28px; background: var(--c-bg-alt);
    border-bottom: 1px solid var(--c-border-light);
}
.ps-num {
    display: block; font-size: 11px; font-weight: 700;
    text-transform: uppercase; letter-spacing: 1.5px;
    color: var(--c-accent); margin-bottom: 6px;
}
.ps-header h3 { font-size: 1.1rem; font-weight: 700; color: var(--c-text); }
.ps-body { padding: 24px 28px; }
.ps-setup, .ps-question {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
    margin-bottom: 12px;
}
.ps-question { font-size: 1rem; margin-bottom: 20px; }
.ps-question strong { color: var(--c-text); }
.ps-options { display: flex; flex-direction: column; gap: 10px; }
.ps-opt {
    display: flex; align-items: flex-start; gap: 12px;
    padding: 16px 18px; background: var(--c-bg-alt);
    border: 2px solid transparent; border-radius: var(--r-lg);
    cursor: pointer; transition: all 0.2s var(--ease);
    text-align: left; font-family: inherit; font-size: 15px;
    color: var(--c-text); width: 100%;
}
.ps-opt:hover { border-color: var(--c-border); background: var(--c-bg); }
.ps-opt:disabled { cursor: default; }
.ps-opt-letter {
    width: 28px; height: 28px; border-radius: 50%;
    background: var(--c-card); border: 1.5px solid var(--c-border);
    display: flex; align-items: center; justify-content: center;
    font-size: 12px; font-weight: 700; color: var(--c-text-3);
    flex-shrink: 0; transition: all 0.2s;
}
.ps-opt:hover .ps-opt-letter { border-color: var(--c-text-3); color: var(--c-text-2); }
.ps-opt-right {
    border-color: var(--c-green) !important;
    background: var(--c-green-light) !important;
}
.ps-opt-right .ps-opt-letter {
    background: var(--c-green) !important;
    border-color: var(--c-green) !important;
    color: white !important;
}
.ps-opt-wrong {
    border-color: var(--c-red) !important;
    background: var(--c-red-light) !important;
}
.ps-opt-wrong .ps-opt-letter {
    background: var(--c-red) !important;
    border-color: var(--c-red) !important;
    color: white !important;
}
.ps-feedback {
    margin-top: 14px; padding: 14px 18px; border-radius: var(--r);
    font-size: 14px; line-height: 1.6; display: none;
    align-items: flex-start; gap: 10px;
    background: var(--c-blue-light); border-left: 3px solid var(--c-blue);
}
.ps-fb-show { display: flex; }
.ps-fb-icon { font-size: 1.2rem; flex-shrink: 0; }

/* ============================================
   06 常见误区
   ============================================ */
.mistakes-list { display: flex; flex-direction: column; gap: 16px; }
.mistake-item {
    display: flex; gap: 20px;
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); padding: 28px 32px;
    box-shadow: var(--shadow); transition: all 0.3s var(--ease);
}
.mistake-item:hover { box-shadow: var(--shadow-hover); }
.mistake-num {
    width: 32px; height: 32px; border-radius: 50%;
    background: var(--c-red-light); color: var(--c-red);
    display: flex; align-items: center; justify-content: center;
    font-size: 12px; font-weight: 700; flex-shrink: 0; margin-top: 2px;
}
.mistake-content { flex: 1; }
.mistake-content h3 {
    font-size: 1.05rem; font-weight: 700; margin-bottom: 8px;
    color: var(--c-text);
}
.mistake-content > p {
    font-size: 0.95rem; color: var(--c-text-2); line-height: 1.7;
    margin-bottom: 14px;
}
.mistake-content > p strong { color: var(--c-text); }
.mistake-example { display: flex; flex-direction: column; gap: 6px; }
.me-wrong, .me-right {
    font-size: 13px; padding: 10px 14px;
    border-radius: var(--r); line-height: 1.5;
}
.me-wrong { background: var(--c-red-light); color: #991b1b; }
.me-right { background: var(--c-green-light); color: #14532d; }

/* ============================================
   07 自检清单
   ============================================ */
.checklist {
    display: flex; flex-direction: column; gap: 12px;
    margin-bottom: 28px;
}
.check-item {
    display: flex; align-items: flex-start; gap: 14px;
    padding: 18px 22px; background: var(--c-card);
    border: 1px solid var(--c-border); border-radius: var(--r-lg);
    cursor: pointer; transition: all 0.2s var(--ease);
    box-shadow: var(--shadow);
}
.check-item:hover { border-color: var(--c-accent-soft); box-shadow: var(--shadow-hover); }
.check-box {
    width: 20px; height: 20px; border: 2px solid var(--c-border);
    border-radius: 5px; appearance: none; -webkit-appearance: none;
    flex-shrink: 0; margin-top: 2px; cursor: pointer;
    transition: all 0.2s; position: relative;
}
.check-box:checked { background: var(--c-accent); border-color: var(--c-accent); }
.check-box:checked::after {
    content: ''; position: absolute; left: 5px; top: 1px;
    width: 5px; height: 10px; border: solid white;
    border-width: 0 2px 2px 0; transform: rotate(45deg);
}
.check-text {
    font-size: 0.97rem; color: var(--c-text-2); line-height: 1.6;
}
.check-text strong { color: var(--c-text); font-weight: 600; }
.checklist-result {
    text-align: center; padding: 20px; background: var(--c-card);
    border: 1px solid var(--c-border); border-radius: var(--r-lg);
    font-size: 1rem; color: var(--c-text-3); box-shadow: var(--shadow);
}
.checklist-result strong { color: var(--c-text); }
.cr-ok { border-color: var(--c-accent-soft); background: var(--c-accent-light); color: #9a3412; }
.cr-good { border-color: var(--c-green-soft); background: var(--c-green-light); color: #14532d; }

/* ============================================
   08 总结
   ============================================ */
.summary-card {
    background: var(--c-card); border: 1px solid var(--c-border);
    border-radius: var(--r-xl); padding: 40px;
    margin-bottom: 40px; box-shadow: var(--shadow);
}
.octalysis-summary {
    display: grid; grid-template-columns: repeat(4, 1fr);
    gap: 10px; margin-bottom: 32px;
}
.os-item {
    display: flex; flex-direction: column; align-items: center;
    text-align: center; gap: 3px;
    padding: 16px 10px; background: var(--c-bg-alt);
    border: 2px solid var(--c-border); border-radius: var(--r-lg);
    transition: all 0.3s var(--ease);
}
.os-item:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); }
.os-item:nth-child(1) { border-color: var(--c-blue-soft); }
.os-item:nth-child(2) { border-color: var(--c-green-soft); }
.os-item:nth-child(3) { border-color: var(--c-yellow-soft); }
.os-item:nth-child(4) { border-color: var(--c-purple-soft); }
.os-item:nth-child(5) { border-color: var(--c-pink-soft); }
.os-item:nth-child(6) { border-color: var(--c-red-light); }
.os-item:nth-child(7) { border-color: var(--c-teal-soft); }
.os-item:nth-child(8) { border-color: var(--c-indigo-soft); }
.os-num { font-size: 10px; font-weight: 700; color: var(--c-text-4); }
.os-icon { font-size: 1.4rem; }
.os-name { font-size: 12px; font-weight: 700; color: var(--c-text); }

.summary-formula {
    display: flex; align-items: center; justify-content: center;
    gap: 12px; flex-wrap: wrap;
    padding-top: 24px; border-top: 1px solid var(--c-border-light);
}
.sf-left, .sf-right {
    font-size: 14px; font-weight: 700;
    padding: 8px 16px; border-radius: var(--r);
}
.sf-left { background: var(--c-bg-alt); color: var(--c-text-3); border: 1px solid var(--c-border); }
.sf-right { background: var(--c-accent-light); color: var(--c-accent); border: 1px solid var(--c-accent-soft); }
.sf-op { font-size: 13px; color: var(--c-text-4); }
.sf-vs { font-size: 12px; font-weight: 700; color: var(--c-text-4); text-transform: uppercase; letter-spacing: 1px; }

.final-quote {
    text-align: center; max-width: 520px;
    margin: 0 auto; padding: 32px 0;
}
.final-quote p {
    font-size: 1.25rem; color: var(--c-text-2); line-height: 1.8;
    font-style: italic;
}
.final-quote p strong { color: var(--c-accent); font-style: normal; }

/* ============================================
   页脚
   ============================================ */
.site-footer {
    text-align: center; padding: 48px 24px;
    background: var(--c-text); color: var(--c-text-4);
}
.site-footer p { font-size: 14px; }
.sf-sub { margin-top: 4px; font-size: 13px; opacity: 0.7; }

/* ============================================
   滚动显示动画
   ============================================ */
.reveal {
    opacity: 0; transform: translateY(24px);
    transition: opacity 0.6s var(--ease), transform 0.6s var(--ease);
}
.reveal.is-visible { opacity: 1; transform: translateY(0); }

/* ============================================
   响应式
   ============================================ */
@media (max-width: 768px) {
    :root { --s-section: 72px; }
    .cover-title { font-size: 2.4rem; }
    .cover-cta { flex-direction: column; align-items: center; }
    .cover-meta { flex-wrap: wrap; }
    .analogy-content { grid-template-columns: 1fr; }
    .analogy-vs { text-align: center; }
    .op-items { grid-template-columns: repeat(2, 1fr); }
    .octalysis-summary { grid-template-columns: repeat(2, 1fr); }
    .case-process-flow { grid-template-columns: 1fr; }
    .mistake-item { flex-direction: column; gap: 12px; }
    .definition-box { padding: 28px 20px; }
    .drive-card { padding: 24px; }
    .case-body { padding: 20px; }
    .case-header { padding: 20px; }
    .ps-body { padding: 20px; }
}
@media (max-width: 480px) {
    .chapter-title { font-size: 1.4rem; }
    .definition-text { font-size: 1.05rem; }
    .btn-main, .btn-ghost { width: 100%; justify-content: center; }
}

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--c-bg); }
::-webkit-scrollbar-thumb { background: var(--c-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--c-text-4); }

@media (prefers-reduced-motion: reduce) {
    * { animation: none !important; transition: none !important; }
}