/* ===== CSS Variables ===== */
:root {
  --color-primary:#059669;--color-primary-light:#10b981;--color-primary-dark:#047857;
  --color-secondary:#0891b2;--color-accent:#06b6d4;
  --color-blue:#3b82f6;--color-amber:#f59e0b;--color-purple:#8b5cf6;--color-pink:#ec4899;
  --color-teal:#14b8a6;--color-indigo:#6366f1;--color-emerald:#22c55e;--color-red:#ef4444;
  --gray-50:#f8fafc;--gray-100:#f1f5f9;--gray-200:#e2e8f0;--gray-300:#cbd5e1;--gray-400:#94a3b8;--gray-500:#64748b;--gray-600:#475569;--gray-700:#334155;--gray-800:#1e293b;--gray-900:#0f172a;
  --font-sans:'Inter','Noto Sans SC',-apple-system,BlinkMacSystemFont,sans-serif;
  --radius-sm:6px;--radius-md:10px;--radius-lg:16px;--radius-xl:24px;--radius-full:9999px;
  --shadow-sm:0 1px 2px rgba(0,0,0,.05);--shadow-md:0 4px 12px rgba(0,0,0,.08);--shadow-lg:0 10px 40px rgba(0,0,0,.1);--shadow-xl:0 20px 60px rgba(0,0,0,.15);
  --ease-out:cubic-bezier(.16,1,.3,1);--transition-fast:150ms var(--ease-out);--transition-base:250ms var(--ease-out);--transition-slow:400ms var(--ease-out);
  --navbar-height:72px;--container-max:1200px;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:var(--navbar-height)}
body{font-family:var(--font-sans);color:var(--gray-800);background:white;line-height:1.7;font-size:16px;overflow-x:hidden;antialiased}
img,svg{display:block;max-width:100%}a{text-decoration:none;color:inherit}button{cursor:pointer;border:none;background:none;font-family:inherit;font-size:inherit}
.container{width:100%;max-width:var(--container-max);margin:0 auto;padding:0 1.5rem}

/* Navbar */
.navbar{position:fixed;top:0;left:0;right:0;z-index:1000;height:var(--navbar-height);background:rgba(255,255,255,.85);backdrop-filter:blur(16px) saturate(180%);border-bottom:1px solid rgba(0,0,0,.06);transition:all .25s ease}
.navbar.scrolled{box-shadow:var(--shadow-md);background:rgba(255,255,255,.95)}
.navbar__container{display:flex;align-items:center;justify-content:space-between;height:100%;max-width:var(--container-max);margin:0 auto;padding:0 1.5rem}
.navbar__brand{display:flex;align-items:center;gap:12px}.navbar__logo-icon{width:38px;height:38px}
.navbar__course{display:block;font-size:14px;font-weight:700;color:var(--gray-900)}.navbar__sub{display:block;font-size:11px;color:var(--color-primary);font-weight:600}
.navbar__toggle{display:none;flex-direction:column;gap:5px;padding:8px;width:36px;height:36px;justify-content:center;align-items:center}
.navbar__toggle span{display:block;width:20px;height:2px;background:var(--gray-700);border-radius:2px;transition:all .25s ease;transform-origin:center}
.navbar__toggle.active span:nth-child(1){transform:rotate(45deg) translate(5px,5px)}.navbar__toggle.active span:nth-child(2){opacity:0}.navbar__toggle.active span:nth-child(3){transform:rotate(-45deg) translate(5px,-5px)}
.navbar__menu{display:flex;align-items:center;gap:4px}
.navbar__link{padding:8px 14px;font-size:14px;font-weight:500;color:var(--gray-600);border-radius:6px;transition:all .15s ease}
.navbar__link:hover,.navbar__link.active{color:var(--color-primary);background:rgba(5,150,105,.07)}
.navbar__link.active::after{content:'';position:absolute;bottom:2px;left:50%;transform:translateX(-50%);width:18px;height:2.5px;background:var(--color-primary);border-radius:2px}
.navbar__cta{padding:8px 18px;font-size:13px;font-weight:600;color:white!important;background:linear-gradient(135deg,var(--color-primary),var(--color-secondary));border-radius:6px}
.navbar__cta:hover{opacity:.9;transform:translateY(-1px)}

/* Hero */
.hero{position:relative;min-height:92vh;display:flex;align-items:center;overflow:hidden;padding:calc(var(--navbar-height)+4rem) 0 4rem}
.hero__bg{position:absolute;inset:0;pointer-events:none}
.hero__pattern{position:absolute;inset:0;background-image:radial-gradient(circle at 1px 1px,rgba(5,150,105,.08) 1px,transparent 0);background-size:32px 32px}
.hero__gradient-overlay{position:absolute;inset:0;background:radial-gradient(ellipse at 70% 30%,rgba(6,182,212,.1) 0%,transparent 60%),radial-gradient(ellipse at 20% 80%,rgba(139,92,246,.08) 0%,transparent 55%)}
.hero__content{position:relative;z-index:2;max-width:720px}
.hero__badge{display:inline-flex;align-items:center;gap:8px;padding:7px 16px;background:rgba(5,150,105,.08);border:1px solid rgba(5,150,105,.15);border-radius:9999px;font-size:13px;font-weight:600;color:var(--color-primary-dark);margin-bottom:1.5rem;animation:fadeInUp .6s ease both}
.hero__title{font-size:clamp(2.5rem,5vw,4rem);font-weight:800;line-height:1.15;color:var(--gray-900);letter-spacing:-.02em;margin-bottom:1.25rem;animation:fadeInUp .6s .1s ease both}
.text-accent{background:linear-gradient(135deg,var(--color-primary),var(--color-accent),var(--color-indigo));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero__desc{font-size:clamp(1rem,1.8vw,1.175rem);color:var(--gray-500);line-height:1.8;max-width:580px;margin-bottom:2rem;animation:fadeInUp .6s .2s ease both}
.hero__info-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:1rem;margin-bottom:2rem;animation:fadeInUp .6s .3s ease both}
.hero__info-item{text-align:center;padding:1rem;background:rgba(255,255,255,.7);backdrop-filter:blur(8px);border:1px solid rgba(0,0,0,.06);border-radius:10px}
.hero__info-num{display:block;font-size:1.5rem;font-weight:800;color:var(--gray-900)}.hero__info-label{font-size:12px;color:var(--gray-500);font-weight:500}
.hero__actions{display:flex;gap:1rem;flex-wrap:wrap;animation:fadeInUp .6s .4s ease both}
.hero__deco{position:absolute;inset:0;pointer-events:none;overflow:hidden}
.hero__deco-block--1{position:absolute;top:15%;right:8%;width:120px;height:120px;background:linear-gradient(135deg,rgba(5,150,105,.12),rgba(6,182,212,.08));border-radius:24px;transform:rotate(12deg);animation:float 8s ease-in-out infinite}
.hero__deco-block--2{position:absolute;bottom:25%;right:18%;width:80px;height:80px;background:linear-gradient(135deg,rgba(139,92,246,.12),rgba(236,72,153,.08));border-radius:20px;transform:rotate(-8deg);animation:float 10s ease-in-out infinite reverse}
.hero__deco-circle{position:absolute;top:30%;right:25%;width:200px;height:200px;border:1.5px solid rgba(5,150,105,.12);border-radius:50%;animation:pulse-ring 6s ease-in-out infinite}
.hero__deco-line{position:absolute;bottom:20%;right:5%;width:160px;height:2px;background:linear-gradient(90deg,transparent,rgba(5,150,105,.2),transparent);transform:rotate(-30deg)}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 26px;font-size:15px;font-weight:600;border-radius:10px;transition:all .25s ease}
.btn--primary{background:linear-gradient(135deg,var(--color-primary),var(--color-primary-light));color:white;box-shadow:0 4px 16px rgba(5,150,105,.25)}.btn--primary:hover{transform:translateY(-2px);box-shadow:0 8px 24px rgba(5,150,105,.35)}
.btn--outline{border:2px solid var(--gray-300);color:var(--gray-700);background:white}.btn--outline:hover{border-color:var(--color-primary);color:var(--color-primary)}
.btn--ghost{color:var(--gray-600);background:rgba(0,0,0,.03)}.btn--ghost:hover{color:var(--color-primary);background:rgba(5,150,105,.06)}
.btn--lg{padding:14px 32px;font-size:16px;border-radius:16px}
.btn__icon{flex-shrink:0;transition:transform .15s ease}.btn:hover .btn__icon{transform:translateX(3px)}

/* Section */
.section{padding:4rem 0}.section--gray{background:var(--gray-50)}
.section--dark{background:linear-gradient(165deg,#0f172a 0%,#111827 50%,#0c1524 100%);color:white}
.section-header{text-align:center;max-width:640px;margin:0 auto 3rem}.section-header--left{text-align:left;margin-left:0}
.section-header--light .section-title,.section-header--light .section-desc{color:white}
.section-badge{display:inline-flex;width:42px;height:42px;border-radius:12px;font-size:15px;font-weight:800;margin-bottom:1.25rem;align-items:center;justify-content:center}
.section-badge--green{background:rgba(5,150,105,.1);color:var(--color-primary)}.section-badge--blue{background:rgba(59,130,246,.1);color:var(--color-blue)}
.section-badge--amber{background:rgba(245,158,11,.1);color:var(--color-amber-dark)}.section-badge--purple{background:rgba(139,92,246,.1);color:var(--color-purple)}
.section-badge--accent{background:linear-gradient(135deg,rgba(6,182,212,.15),rgba(99,102,241,.15));color:var(--color-accent)}
.section-title{font-size:clamp(1.75rem,3.5vw,2.5rem);font-weight:800;color:var(--gray-900);letter-spacing:-.02em;line-height:1.2;margin-bottom:1rem}
.section-desc{font-size:1.1rem;color:var(--gray-500);line-height:1.7}.section-desc--light{color:rgba(148,163,184,.85)};

/* Intro Grid */
.intro-grid{display:grid;grid-template-columns:1fr 1fr;gap:1.25rem}
.intro-card{background:white;border-radius:16px;padding:1.5rem;border:1px solid rgba(0,0,0,.06);transition:all .25s ease}
.intro-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg);border-color:transparent}
.intro-card--main{grid-column:1/-1}.intro-card--highlight{background:linear-gradient(135deg,#f0fdf4,#ecfdf5);border-color:rgba(5,150,105,.15)}
.intro-card__icon{width:52px;height:52px;display:flex;align-items:center;justify-content:center;border-radius:10px;background:rgba(5,150,105,.1);color:var(--color-primary);margin-bottom:1.25rem}
.intro-card__icon svg{width:28px;height:28px}.intro-card__icon--blue{background:rgba(59,130,246,.1);color:var(--color-blue)}.intro-card__icon--amber{background:rgba(245,158,11,.1);color:var(--color-amber-dark)}.intro-card__icon--purple{background:rgba(139,92,246,.1);color:var(--color-purple)}
.intro-card__title{font-size:1.25rem;font-weight:700;color:var(--gray-900);margin-bottom:1rem}
.intro-card__text{font-size:.95rem;color:var(--gray-600);line-height:1.8}
.intro-card__list li{position:relative;padding:6px 0 6px 24px;font-size:.95rem;color:var(--gray-600)}
.intro-card__list li::before{content:'';position:absolute;left:6px;top:14px;width:6px;height:6px;border-radius:50%;background:var(--color-primary)}
.intro-card__tags{display:flex;flex-wrap:wrap;gap:8px}
.tag{display:inline-block;padding:5px 14px;font-size:13px;font-weight:600;border-radius:9999px}
.tag--green{background:rgba(5,150,105,.1);color:var(--color-primary-dark)}.tag--blue{background:rgba(59,130,246,.1);color:var(--color-blue)}.tag--amber{background:rgba(245,158,11,.1);color:var(--color-amber-dark)}.tag--purple{background:rgba(139,92,246,.1);color:var(--color-purple)}.tag--teal{background:rgba(20,184,166,.1);color:var(--color-teal)}.tag--outline{background:white;border:1.5px solid var(--gray-200);color:var(--gray-600)}
.feature-highlights{display:flex;flex-direction:column;gap:1rem}
.feature-highlight{display:flex;align-items:flex-start;gap:1rem}.feature-highlight__num{font-size:1.5rem;font-weight:900;color:var(--color-primary);opacity:.4;line-height:1;min-width:36px}
.feature-highlight__content strong{font-size:.95rem;color:var(--gray-900)}.feature-highlight__content span{font-size:.86rem;color:var(--gray-500)}


/* ===== 知识图谱 静态拓扑图 ===== */

/* 容器 */
.knowledge-graph{width:100%;border-radius:20px;background:linear-gradient(165deg,rgba(15,23,42,.85) 0%,#0c1220 40%,#0a0f1c 100%);border:1px solid rgba(255,255,255,.06);overflow:hidden;margin-bottom:1.5rem;position:relative}
.knowledge-graph::before{content:'';position:absolute;inset:0;background:radial-gradient(ellipse 50% 60% at 50% 45%,rgba(34,197,94,.06) 0%,transparent 60%),radial-gradient(ellipse 38% 30% at 20% 22%,rgba(96,165,250,.04) 0%,transparent 55%),radial-gradient(ellipse 38% 30% at 80% 75%,rgba(52,211,153,.03) 0%,transparent 55%);pointer-events:none}
.knowledge-svg{width:100%;min-height:520px;height:auto;display:block}

/* --- 背景装饰（静态） --- */
.kg-bg .core-glow-circle{opacity:.5}
.kg-bg .dot-grid-rect{opacity:.7}

/* --- 连线（静态） --- */
.graph-link{transition:opacity .35s ease,stroke-width .3s ease;stroke-linecap:round;fill:none}
.main-link{opacity:.5}
.topo-link{transition:opacity .4s ease;stroke-linecap:round;fill:none}
.topo-link:hover{opacity:.7!important}
.topo-link--sym{stroke-dasharray:5 5}

.sub-link{opacity:.4;transition:opacity .3s ease}

/* --- 悬停高亮连线 --- */
.graph-link.link-active{stroke-width:3.5;opacity:.9!important;filter:drop-shadow(0 0 4px currentColor)}
.main-link.link-active--theory{stroke:url(#linkCoreTheory)}.main-link.link-active--method{stroke:url(#linkCoreMethod)}
.main-link.link-active--elements{stroke:url(#linkCoreElements)}.main-link.link-active--tech{stroke:url(#linkCoreTech)}
.main-link.link-active--cases{stroke:url(#linkCoreCases)}.main-link.link-active--practice{stroke:url(#linkCorePractice)}
.sub-link.sub-active{stroke-width:2.5;opacity:.8!important}

/* --- 节点（静态 + 悬停效果） --- */
.kg-node{transition:filter .35s ease}
.kg-node:hover{filter:brightness(1.2) saturate(1.15)}

/* --- 子节点 --- */
.kg-subnode{transition:opacity .35s ease,filter .35s ease;cursor:default}
.sub-border{transition:all .35s ease}
.kg-subnode.highlighted .sub-border{stroke-width:2.2;opacity:.85;filter:drop-shadow(0 0 4px currentColor)}
.kg-subnode.highlighted .sub-bg{filter:brightness(1.25)!important}
.kg-subnode.dimmed{opacity:.18!important}

/* --- 面板 --- */
.knowledge-panel{background:rgba(255,255,255,.97);backdrop-filter:blur(16px);border-radius:18px;padding:0;overflow:hidden;box-shadow:0 20px 60px rgba(0,0,0,.12),0 4px 16px rgba(0,0,0,.06);margin-top:1.5rem;border:1px solid rgba(0,0,0,.05);animation:panelSlideUp .5s cubic-bezier(.22,1,.36,1)}
@keyframes panelSlideUp{from{opacity:0;transform:translateY(20px) scale(.98)}to{opacity:1;transform:none}}
.knowledge-panel[hidden]{display:none}
.knowledge-panel__header{display:flex;align-items:center;justify-content:space-between;padding:1.25rem 1.75rem;background:linear-gradient(135deg,#f8fafc,#f1f5f9);border-bottom:1px solid #e2e8f0}
.knowledge-panel__title{font-size:1.15rem;font-weight:700;color:var(--gray-900)}
.knowledge-panel__close{width:36px;height:36px;display:flex;align-items:center;justify-content:center;font-size:22px;color:var(--gray-500);border-radius:50%;transition:all .2s ease}
.knowledge-panel__close:hover{background:rgba(0,0,0,.06);color:var(--gray-900);transform:rotate(90deg)}
.knowledge-panel__body{padding:1.75rem}
.knowledge-panel__body h4{font-size:1.02rem;font-weight:700;margin:1.35rem 0 .55rem;color:var(--gray-900)}
.knowledge-panel__body p{font-size:.93rem;color:var(--gray-600);line-height:1.78;margin-bottom:.5rem}
.knowledge-panel__body ul{list-style:disc;padding-left:20px;margin-bottom:1.1rem}
.knowledge-panel__body ul li{font-size:.93rem;color:var(--gray-600);line-height:1.72;margin-bottom:4px}

/* --- 图例交互 --- */
.knowledge-legend{display:flex;flex-wrap:wrap;justify-content:center;gap:1rem 2rem;padding:1.15rem 1.75rem;background:rgba(15,23,42,.35);border-radius:12px;border:1px solid rgba(255,255,255,.05)}
.legend-item{display:flex;align-items:center;gap:9px;font-size:13px;color:rgba(148,163,184,.9);padding:5px 12px;border-radius:8px;transition:all .3s ease;cursor:pointer;-webkit-user-select:none;user-select:none}
.legend-item:hover{background:rgba(255,255,255,.08);color:white;transform:translateY(-2px)}
.legend-dot{width:13px;height:13px;border-radius:50%;flex-shrink:0;box-shadow:0 0 4px currentColor}
.legend-dot--core{background:linear-gradient(135deg,#4ade80,#059669);color:#22c55e}.legend-dot--theory{background:linear-gradient(135deg,#60a5fa,#2563eb);color:#3b82f6}
.legend-dot--method{background:linear-gradient(135deg,#fbbf24,#f59e0b);color:#f59e0b}.legend-dot--practice{background:linear-gradient(135deg,#a78bfa,#7c3aed);color:#8b5cf6}
.legend-dot--tech{background:linear-gradient(135deg:#f472b6,#ec4899);color:#ec4899}.legend-dot--case{background:linear-gradient(135deg,#22d3ee,#0891b2);color:#0891b2}

/* 减少动画偏好 */
@media(prefers-reduced-motion:reduce){
  .knowledge-panel{animation:none!important}
}
/* Timeline */
.timeline{position:relative;max-width:820px;margin:0 auto;padding-left:48px}
.timeline::before{content:'';position:absolute;left:17px;top:0;bottom:0;width:2px;background:linear-gradient(to bottom,var(--color-primary),var(--color-secondary),var(--color-indigo));border-radius:2px;opacity:.2}
.timeline__item{position:relative;margin-bottom:2rem}.timeline__item:last-child{margin-bottom:0}
.timeline__marker{position:absolute;left:-48px;top:4px;width:36px;height:36px;border-radius:50%;display:flex;align-items:center;justify-content:center;background:white;border:2px solid #e2e8f0;z-index:2}
.timeline__marker--active{background:linear-gradient(135deg,var(--color-primary),var(--color-primary-light));border-color:transparent;box-shadow:0 0 0 4px rgba(5,150,105,.15)}
.timeline__num{font-size:13px;font-weight:800;color:var(--gray-500)}.timeline__marker--active .timeline__num{color:white}
.timeline__card{background:white;border-radius:16px;padding:1.5rem;border:1px solid rgba(0,0,0,.06);transition:all .25s ease}.timeline__card:hover{box-shadow:var(--shadow-lg);transform:translateX(4px)}
.timeline__phase{font-size:.82rem;font-weight:700;color:var(--color-primary);letter-spacing:.04em;text-transform:uppercase;margin-bottom:.5rem}
.timeline__title{font-size:1.2rem;font-weight:700;color:var(--gray-900);margin-bottom:1rem}
.timeline__tasks{display:flex;flex-direction:column;gap:6px;margin-bottom:1.25rem}
.timeline__tasks li{position:relative;padding-left:22px;font-size:.93rem;color:var(--gray-600);line-height:1.6}
.timeline__tasks li::before{content:'';position:absolute;left:4px;top:9px;width:7px;height:7px;border-radius:2px;background:var(--color-primary-light);opacity:.6}
.timeline__deliverable{display:inline-flex;align-items:center;gap:8px;padding:8px 16px;background:rgba(5,150,105,.06);border-radius:10px;font-size:.87rem;font-weight:600;color:var(--color-primary-dark)}

/* Homework & Evaluation */
.homework-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:1.25rem;margin-bottom:3rem}
.hw-card{background:white;border-radius:16px;overflow:hidden;border:1px solid rgba(0,0,0,.06);transition:all .25s ease}.hw-card:hover{transform:translateY(-4px);box-shadow:var(--shadow-lg)}
.hw-card__header{display:flex;align-items:center;justify-content:space-between;padding:.75rem 1.5rem;color:white}
.hw-card__header--green{background:linear-gradient(135deg,var(--color-primary),var(--color-emerald))}.hw-card__header--blue{background:linear-gradient(135deg,var(--color-blue),var(--color-indigo))}.hw-card__header--amber{background:linear-gradient(135deg,var(--color-amber),#f97316)}.hw-card__header--purple{background:linear-gradient(135deg,var(--color-purple),var(--color-pink))}
.hw-card__num{font-size:14px;font-weight:800}.hw-card__type{font-size:12px;font-weight:500;opacity:.85;background:rgba(255,255,255,.2);padding:2px 10px;border-radius:9999px}
.hw-card__body{padding:1.5rem}.hw-card__title{font-size:1.15rem;font-weight:700;color:var(--gray-900);margin-bottom:.5rem}.hw-card__desc{font-size:.9rem;color:var(--gray-600);line-height:1.7;margin-bottom:1rem}
.hw-card__meta{display:flex;gap:1.5rem;margin-bottom:1rem}.hw-card__meta span{display:flex;align-items:center;gap:5px;font-size:.83rem;color:var(--gray-500)}
.hw-card__requirements li{position:relative;padding:4px 0 4px 20px;font-size:.86rem;color:var(--gray-600)}.hw-card__requirements li::before{content:'✓';position:absolute;left:0;color:var(--color-primary);font-weight:700;font-size:.8rem}
.evaluation-section{background:white;border-radius:16px;padding:2rem;border:1px solid rgba(0,0,0,.06)}
.evaluation-title{display:flex;align-items:center;gap:10px;font-size:1.2rem;font-weight:700;margin-bottom:1.5rem}.evaluation-title svg{color:var(--color-primary)}
.evaluation-bars{display:flex;flex-direction:column;gap:1.25rem;margin-bottom:1rem}
.eval-bar-info{display:flex;justify-content:space-between;margin-bottom:6px}.eval-bar-info span{font-size:.9rem;color:var(--gray-700)}.eval-bar-info strong{font-size:.9rem;font-weight:800}
.eval-bar{height:10px;background:#f1f5f9;border-radius:9999px;overflow:hidden}.eval-bar__fill{height:100%;border-radius:9999px}
.eval-bar--purple{background:linear-gradient(90deg,var(--color-purple),var(--color-pink))}.eval-bar--amber{background:linear-gradient(90deg,var(--color-amber),#f97316)}.eval-bar--blue{background:linear-gradient(90deg,var(--color-blue),var(--color-indigo))}.eval-bar--green{background:linear-gradient(90deg,var(--color-primary),var(--color-teal))}
.evaluation-note{padding-top:1.25rem;border-top:1px solid #e2e8f0}.evaluation-note p{font-size:.88rem;color:var(--gray-500)}

/* AI Assistant */
.ai-section{background:linear-gradient(180deg,#f8fafc 0%,white 100%)}
.ai-layout{display:grid;grid-template-columns:1fr 380px;gap:1.5rem;align-items:start}
.chat-panel{background:white;border-radius:16px;border:1px solid rgba(0,0,0,.08);overflow:hidden;box-shadow:var(--shadow-md)}
.chat-panel__header{display:flex;align-items:center;gap:1rem;padding:1.25rem;background:linear-gradient(135deg,rgba(6,182,212,.06),rgba(99,102,241,.06));border-bottom:1px solid #e2e8f0}
.chat-name{font-size:1rem;font-weight:700}.chat-status{display:flex;align-items:center;gap:6px;font-size:.8rem;color:var(--gray-500)}
.status-dot{width:7px;height:7px;border-radius:50%;background:var(--color-emerald);animation:pulse-dot 2s infinite}
.chat-messages{height:380px;overflow-y:auto;padding:1.25rem;display:flex;flex-direction:column;gap:1rem}
.chat-msg{display:flex;gap:12px;max-width:85%;animation:msgIn .3s ease}
.chat-msg--user{align-self:flex-end;flex-direction:row-reverse}
.chat-msg__avatar{flex-shrink:0;width:36px;height:36px;border-radius:50%;overflow:hidden}
.chat-msg__bubble{padding:12px 16px;border-radius:16px;font-size:.9rem;line-height:1.7}
.chat-msg--ai .chat-msg__bubble{background:#f8fafc;color:var(--gray-700);border-bottom-left-radius:4px}
.chat-msg--user .chat-msg__bubble{background:linear-gradient(135deg,var(--color-primary),var(--color-secondary));color:white;border-bottom-right-radius:4px}
.chat-msg__list{margin:8px 0;padding-left:16px;list-style:disc}.chat-msg__list li{font-size:.87rem;line-height:1.6;margin-bottom:3px}
.chat-input-area{border-top:1px solid #e2e8f0;padding:1rem}
.chat-suggestions{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:.5rem}
.chat-tag{padding:5px 12px;font-size:.78rem;font-weight:500;color:var(--color-primary-dark);background:rgba(5,150,105,.06);border:1px solid rgba(5,150,105,.12);border-radius:9999px;white-space:nowrap}
.chat-tag:hover{background:rgba(5,150,105,.12)}
.chat-form{display:flex;gap:8px}.chat-input{flex:1;padding:10px 16px;border:1.5px solid #e2e8f0;border-radius:10px;font-size:.9rem;outline:none}
.chat-input:focus{border-color:var(--color-primary);box-shadow:0 0 0 3px rgba(5,150,105,.1)}
.chat-send{width:42px;height:42px;display:flex;align-items:center;justify-content:center;background:linear-gradient(135deg,var(--color-primary),var(--color-secondary));color:white;border-radius:10px;flex-shrink:0}
.chat-send:hover{transform:scale(1.05);box-shadow:0 4px 12px rgba(5,150,105,.3)}
.ai-features{display:grid;grid-template-columns:1fr 1fr;gap:.75rem}
.ai-feature-card{background:white;border-radius:16px;padding:1.5rem;border:1px solid rgba(0,0,0,.06);transition:all .25s ease}
.ai-feature-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg)}
.ai-feature-icon{width:46px;height:46px;display:flex;align-items:center;justify-content:center;border-radius:10px;margin-bottom:1rem}.ai-feature-icon svg{width:22px;height:22px}
.ai-feature-icon--cyan{background:rgba(6,182,212,.1);color:var(--color-cyan)}.ai-feature-icon--indigo{background:rgba(99,102,241,.1);color:var(--color-indigo)}.ai-feature-icon--emerald{background:rgba(34,197,94,.1);color:var(--color-emerald)}.ai-feature-icon--rose{background:rgba(236,72,153,.1);color:#be185d}
.ai-feature-card h4{font-size:.98rem;font-weight:700;color:var(--gray-900);margin-bottom:6px}.ai-feature-card p{font-size:.85rem;color:var(--gray-500)}

/* Footer */
.footer{background:var(--gray-900);color:var(--gray-400);padding:3rem 0 1.25rem}
.footer__inner{display:flex;align-items:center;justify-content:space-between;gap:1.5rem;flex-wrap:wrap}
.footer__brand{display:flex;align-items:center;gap:14px}.footer__logo{width:36px;height:36px}
.footer__course{font-size:1rem;font-weight:700;color:white}.footer__dept{font-size:.83rem;color:var(--gray-500)}
.footer__links{display:flex;gap:1.5rem}.footer__links a{font-size:.88rem;color:var(--gray-500)}.footer__links a:hover{color:white}
.footer__copy{width:100%;text-align:center;font-size:.82rem;color:var(--gray-600);padding-top:1.25rem;border-top:1px solid rgba(255,255,255,.06);margin-top:1.25rem}

/* Animations */
@keyframes fadeInUp{from{opacity:0;transform:translateY(24px)}to{opacity:1;transform:translateY(0)}}
@keyframes slideUp{from{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}
@keyframes float{0%,100%{transform:rotate(12deg) translateY(0)}50%{transform:rotate(12deg) translateY(-16px)}}
@keyframes pulse-ring{0%,100%{opacity:.3;transform:scale(1)}50%{opacity:.6;transform:scale(1.05)}}
@keyframes pulse-dot{0%,100%{opacity:1}50%{opacity:.4}}@keyframes msgIn{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}
[data-aos]{opacity:0;transform:translateY(24px);transition:opacity .6s ease,transform .6s ease}[data-aos].aos-animate{opacity:1;transform:none}

@media (max-width:1024px){.ai-layout{grid-template-columns:1fr}.ai-features{order:-1;grid-template-columns:repeat(4,1fr)}.hero__info-grid{grid-template-columns:repeat(2,1fr)}}
@media (max-width:768px){:root{--navbar-height:64px}.container{padding:0 1rem}
.navbar__menu{display:none;position:fixed;top:64px;left:0;right:0;background:white;flex-direction:column;padding:1.25rem;box-shadow:var(--shadow-lg);z-index:999}
.navbar__menu.active{display:flex}.navbar__link,.navbar__cta{width:100%;padding:12px 16px;text-align:center}.navbar__link.active::after{display:none}.navbar__toggle{display:flex}
.hero{min-height:auto;padding:calc(64px+3rem)0 3rem}.hero__title{font-size:clamp(2rem,6vw,2.8rem)}
.intro-grid,.homework-grid{grid-template-columns:1fr}.intro-card--main{grid-column:auto}

.timeline{padding-left:36px}.timeline__marker{left:-36px;width:30px;height:30px}.ai-features{grid-template-columns:1fr 1fr}.footer__inner{flex-direction:column;text-align:center}.footer__links{flex-wrap:wrap;justify-content:center}}
@media (max-width:480px){.hero__actions{flex-direction:column}.btn--lg{width:100%}.section{padding:3rem 0}.section-title{font-size:1.5rem}.chat-messages{height:280px}.ai-features{grid-template-columns:1fr}.knowledge-svg{min-height:440px}}
@media print{.navbar,.hero__deco,.navbar__toggle,.chat-input-area,.chat-send{display:none!important}body{color:black;background:white}.section{break-inside:avoid}}
@media (prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}