*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: "Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif; background: #F9F7FC; color: #1a0a2e; line-height: 1.6; -webkit-font-smoothing: antialiased; }
a { text-decoration: none; color: inherit; }

.course-hero { background: linear-gradient(135deg,#1a0a2e 0%,#3a1a5e 60%,#5a3a7e 100%); color: #fff; padding: 2rem 1.5rem 2.5rem; }
.back-link { display: inline-block; font-size: 0.82rem; color: rgba(255,255,255,0.7); margin-bottom: 1.2rem; transition: color 0.2s; }
.back-link:hover { color: #fff; }
.course-code-badge { display: inline-block; background: rgba(255,255,255,0.15); border-radius: 20px; padding: 4px 14px; font-size: 0.72rem; letter-spacing: 0.08em; margin-bottom: 0.8rem; }
.course-hero h1 { font-size: clamp(1.5rem,4vw,2rem); font-weight: 800; margin-bottom: 0.4rem; line-height: 1.25; }
.hero-sub { font-size: 0.9rem; opacity: 0.75; margin-bottom: 0.8rem; }
.meta-pills { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.meta-pill { background: rgba(255,255,255,0.15); border-radius: 20px; padding: 4px 12px; font-size: 0.72rem; }

.story-card { background: #1a0a2e; color: #d8c8f8; padding: 1.5rem; margin: 0; }
.story-eyebrow { font-size: 0.75rem; font-weight: 700; letter-spacing: 0.1em; color: #b898e8; margin-bottom: 0.5rem; }
.story-title { font-size: 1.05rem; font-weight: 800; color: #fff; margin-bottom: 0.8rem; line-height: 1.35; }
.story-body { font-size: 0.85rem; line-height: 1.85; color: #c0a8e8; }
.story-body strong { color: #e8d8ff; }
.story-quote { margin-top: 1rem; border-left: 3px solid #8868c8; padding-left: 0.8rem; font-size: 0.82rem; font-style: italic; color: #a888d8; line-height: 1.6; }

.driving-question { background: #f0ebff; border-left: 4px solid #7a5ab8; padding: 1rem 1.2rem; margin: 0; }
.dq-label { font-size: 0.65rem; font-weight: 700; letter-spacing: 0.12em; color: #4a2a78; margin-bottom: 0.3rem; }
.dq-text { font-size: 0.95rem; font-weight: 700; color: #1a0a2e; line-height: 1.5; }

.output-box { display: flex; align-items: center; gap: 1rem; background: #fff; border-bottom: 1px solid #e0d8f0; padding: 1rem 1.5rem; }
.output-icon { font-size: 1.8rem; }
.output-label { font-size: 0.65rem; font-weight: 700; letter-spacing: 0.1em; color: #7a5ab8; }
.output-title { font-size: 0.9rem; font-weight: 700; color: #1a0a2e; }

.section-card { background: #fff; border: 1.5px solid #e0d0f8; border-radius: 12px; margin: 1rem 1.5rem; padding: 1rem 1.2rem; }
.section-card h3 { font-size: 0.85rem; font-weight: 700; color: #3a1a5e; margin-bottom: 0.6rem; }
.section-card ul { list-style: none; }
.section-card ul li { font-size: 0.82rem; color: #2a1a4e; padding: 0.25rem 0; padding-left: 1.2rem; position: relative; }
.section-card ul li::before { content: "·"; position: absolute; left: 0.3rem; color: #7a5ab8; }

.phases { padding: 0 0 1rem; }
.phase { border-bottom: 1px solid #e8e0f8; }
.phase-header { display: flex; align-items: center; gap: 0.8rem; padding: 0.9rem 1.5rem; cursor: pointer; user-select: none; }
.phase-header:hover { background: #f5f0ff; }
.phase-num { width: 28px; height: 28px; border-radius: 50%; background: #5a3a7e; color: #fff; font-size: 0.75rem; font-weight: 800; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.phase-title-wrap { flex: 1; }
.phase-title { font-size: 0.9rem; font-weight: 700; color: #1a0a2e; }
.phase-duration { font-size: 0.72rem; color: #7a5ab8; margin-top: 1px; }
.phase-arrow { font-size: 0.7rem; color: #9a7ac8; transition: transform 0.2s; }
.phase.open .phase-arrow { transform: rotate(180deg); }
.phase-body { display: none; padding: 0 1.5rem 1.2rem; }
.phase.open .phase-body { display: block; }

.steps { list-style: none; }
.step { display: flex; gap: 0.7rem; padding: 0.5rem 0; border-bottom: 1px solid #f0e8ff; }
.step:last-child { border-bottom: none; }
.step-num { width: 22px; height: 22px; border-radius: 50%; background: #e8d8ff; color: #5a3a7e; font-size: 0.7rem; font-weight: 800; display: flex; align-items: center; justify-content: center; flex-shrink: 0; margin-top: 2px; }
.step-title { font-size: 0.85rem; font-weight: 700; color: #1a0a2e; margin-bottom: 0.2rem; }
.step-body { font-size: 0.78rem; color: #2a1a4e; line-height: 1.6; }

.data-table { width: 100%; border-collapse: collapse; font-size: 0.78rem; margin: 0.5rem 0; }
.data-table th { background: #5a3a7e; color: #fff; padding: 0.4rem 0.6rem; text-align: left; font-size: 0.72rem; }
.data-table td { padding: 0.35rem 0.6rem; border-bottom: 1px solid #e8d8ff; color: #1a0a2e; }
.data-table tr:nth-child(even) td { background: #f5f0ff; }

.math-box { background: #f0ebff; border: 1.5px solid #c0a8e8; border-radius: 10px; padding: 0.8rem; margin: 0.5rem 0; }
.math-label { font-size: 0.65rem; font-weight: 700; letter-spacing: 0.1em; color: #5a3a7e; margin-bottom: 0.4rem; }
.math-formula { font-family: 'Courier New', monospace; font-size: 0.9rem; font-weight: 700; color: #1a0a2e; margin: 0.3rem 0; }
.math-explain { font-size: 0.75rem; color: #2a1a4e; line-height: 1.7; margin-top: 0.3rem; }

.discussion { list-style: none; }
.discussion li { padding: 0.5rem 0 0.5rem 1.2rem; position: relative; font-size: 0.82rem; color: #1a0a2e; line-height: 1.6; border-bottom: 1px solid #e8d8ff; }
.discussion li::before { content: "?"; position: absolute; left: 0; color: #7a5ab8; font-weight: 700; }
.discussion li:last-child { border-bottom: none; }

.tip-box { background: #e8d8ff; border-radius: 8px; padding: 0.6rem 0.9rem; font-size: 0.78rem; color: #2a1a4e; margin-top: 0.5rem; line-height: 1.6; }

.person-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px,1fr)); gap: 0.6rem; margin: 0.5rem 0; }
.person-card { background: #f5f0ff; border: 1.5px solid #c8b0e8; border-radius: 10px; padding: 0.7rem; text-align: center; }
.person-name { font-size: 0.82rem; font-weight: 700; color: #3a1a5e; margin-bottom: 0.2rem; }
.person-role { font-size: 0.7rem; color: #7a5ab8; margin-bottom: 0.3rem; }
.person-note { font-size: 0.72rem; color: #2a1a4e; line-height: 1.5; }

.course-nav { display: flex; gap: 0.8rem; padding: 1.2rem 1.5rem; background: #fff; border-top: 1px solid #e0d0f8; }
.nav-btn { flex: 1; display: block; text-align: center; padding: 0.7rem; border-radius: 10px; font-size: 0.82rem; font-weight: 700; background: #f0e8ff; color: #3a1a5e; transition: opacity 0.2s; }
.nav-btn:hover { opacity: 0.8; }
.nav-btn-next { background: #5a3a7e; color: #fff; }

.site-footer { text-align: center; padding: 2rem; font-size: 0.82rem; color: #9a7aac; border-top: 1px solid #e0d0f0; }
.site-footer a { color: #7a5ab8; }