/* EcoPath Cambridge – Blue & Gold Dark Theme */
:root {
  --bg-primary:    #080c18;
  --bg-secondary:  #0d1120;
  --bg-card:       #121729;
  --bg-card-hover: #1a2038;
  --bg-input:      #0a0e1c;
  --blue-primary:  #1e40af;
  --blue-light:    #93c5fd;
  --blue-dark:     #1e3a8a;
  --blue-glow:     rgba(30, 64, 175, 0.25);
  --blue-border:   rgba(30, 64, 175, 0.35);
  --gold-primary:  #d97706;
  --gold-light:    #fbbf24;
  --gold-dark:     #92400e;
  --gold-glow:     rgba(217, 119, 6, 0.18);
  --text-primary:  #e0e7ff;
  --text-secondary:#818cf8;
  --text-muted:    #312e81;
  --border-color:  rgba(30, 64, 175, 0.2);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter',sans-serif;background:var(--bg-primary);color:var(--text-primary);line-height:1.6;min-height:100vh;overflow-x:hidden}

/* ── FLOATERS ── */
.floater{position:fixed;bottom:-60px;color:rgba(147,197,253,0.12);pointer-events:none;animation:floatUp linear infinite;z-index:0;font-family:'JetBrains Mono',monospace;font-size:0.85rem;user-select:none}
@keyframes floatUp{to{transform:translateY(-110vh) rotate(20deg);opacity:0}}

/* ── NAVBAR ── */
.navbar{position:sticky;top:0;z-index:100;background:rgba(8,12,24,0.92);backdrop-filter:blur(16px);border-bottom:1px solid var(--border-color)}
.nav-inner{max-width:1280px;margin:0 auto;padding:0 24px;height:64px;display:flex;align-items:center;gap:24px}
.nav-logo{display:flex;align-items:center;gap:10px;text-decoration:none;flex-shrink:0}
.logo-icon{font-size:1.5rem}
.logo-text{font-weight:800;font-size:1.15rem;color:var(--blue-light);letter-spacing:-0.02em}
.logo-sub{font-size:0.72rem;color:var(--text-secondary);font-weight:500;letter-spacing:0.04em;text-transform:uppercase;margin-top:2px}
.nav-links{display:flex;gap:6px;margin-left:auto}
.nav-links a{color:var(--text-secondary);text-decoration:none;padding:6px 14px;border-radius:var(--radius-sm);font-size:0.88rem;font-weight:500;transition:all .2s}
.nav-links a:hover{color:var(--text-primary);background:var(--bg-card)}
.nav-toggle{display:none;background:none;border:1px solid var(--border-color);color:var(--text-secondary);padding:6px 10px;border-radius:var(--radius-sm);cursor:pointer;font-size:1rem}
.mobile-menu{display:none;flex-direction:column;background:var(--bg-secondary);border-bottom:1px solid var(--border-color);padding:12px 24px;gap:4px}
.mobile-menu.open{display:flex}
.mobile-menu a{color:var(--text-secondary);text-decoration:none;padding:10px 14px;border-radius:var(--radius-sm);font-size:0.9rem;transition:all .2s}
.mobile-menu a:hover{color:var(--text-primary);background:var(--bg-card)}
@media(max-width:768px){.nav-links{display:none}.nav-toggle{display:block}}

/* ── MAIN ── */
.main-content{position:relative;z-index:1}

/* ── HERO ── */
.hero{padding:80px 24px 60px;text-align:center;background:radial-gradient(ellipse 80% 60% at 50% 0%,rgba(30,64,175,0.18) 0%,transparent 70%)}
.hero-inner{max-width:780px;margin:0 auto}
.hero-badge{display:inline-block;background:rgba(30,64,175,0.15);border:1px solid var(--blue-border);color:var(--blue-light);font-size:0.8rem;font-weight:600;letter-spacing:.06em;text-transform:uppercase;padding:5px 14px;border-radius:99px;margin-bottom:20px}
.hero-title{font-size:clamp(2rem,5vw,3.4rem);font-weight:800;letter-spacing:-0.03em;line-height:1.1;margin-bottom:16px}
.hero-accent{background:linear-gradient(135deg,var(--gold-light),var(--gold-primary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero-subtitle{color:var(--text-secondary);font-size:1.05rem;max-width:580px;margin:0 auto 28px}
.hero-actions{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-bottom:36px}
.hero-stats{display:flex;gap:32px;justify-content:center;flex-wrap:wrap;padding:20px 0;border-top:1px solid var(--border-color)}
.hero-stat{text-align:center}
.hero-stat-num{display:block;font-size:1.8rem;font-weight:800;color:var(--gold-light)}
.hero-stat-label{font-size:0.78rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em}

/* ── SECTIONS ── */
.section{padding:60px 24px}
.section-alt{background:var(--bg-secondary)}
.section-inner{max-width:1280px;margin:0 auto}
.section-title{font-size:1.5rem;font-weight:700;margin-bottom:8px;display:flex;align-items:center;gap:10px}
.section-title .emoji{font-size:1.3rem}
.section-sub{color:var(--text-secondary);margin-bottom:32px;font-size:0.95rem}

/* ── YEAR GRID ── */
.year-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px}
.year-card{display:block;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:24px;text-decoration:none;transition:all .25s;cursor:pointer}
.year-card:hover{background:var(--bg-card-hover);border-color:var(--blue-border);transform:translateY(-3px);box-shadow:0 12px 32px var(--blue-glow)}
.year-emoji{font-size:2.4rem;margin-bottom:10px}
.year-name{font-size:1.05rem;font-weight:700;color:var(--text-primary);margin-bottom:6px}
.year-desc{font-size:0.83rem;color:var(--text-secondary);margin-bottom:12px;line-height:1.5}
.year-count{font-size:0.8rem;font-weight:600;color:var(--gold-light)}

/* ── SUBJECT PILLS ── */
.subject-pills{display:flex;flex-wrap:wrap;gap:10px}
.subject-pill{display:flex;align-items:center;gap:8px;padding:8px 16px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:99px;font-size:0.88rem;color:var(--text-secondary);font-weight:500}

/* ── FEATURES ── */
.features-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:20px}
.feature-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:24px;transition:border-color .2s}
.feature-card:hover{border-color:var(--blue-border)}
.feature-icon{font-size:2rem;margin-bottom:12px}
.feature-card h3{font-size:1rem;font-weight:700;margin-bottom:8px;color:var(--blue-light)}
.feature-card p{font-size:0.85rem;color:var(--text-secondary);line-height:1.6}

/* ── TOPICS LIST ── */
.topics-list{display:flex;flex-direction:column;gap:10px}
.topic-item{display:flex;align-items:center;gap:16px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:16px 20px;text-decoration:none;transition:all .2s}
.topic-item:hover{background:var(--bg-card-hover);border-color:var(--blue-border);transform:translateX(4px)}
.topic-icon{font-size:1.6rem;flex-shrink:0}
.topic-name{font-weight:600;color:var(--text-primary);font-size:0.95rem}
.topic-desc{font-size:0.8rem;color:var(--text-secondary);margin-top:2px}
.topic-arrow{margin-left:auto;color:var(--text-muted);font-size:1.1rem}

/* ── BADGES ── */
.badge{display:inline-block;padding:3px 10px;border-radius:99px;font-size:0.75rem;font-weight:600;letter-spacing:.03em}
.badge-blue{background:rgba(30,64,175,0.2);color:var(--blue-light);border:1px solid var(--blue-border)}
.badge-gold{background:rgba(217,119,6,0.18);color:var(--gold-light);border:1px solid rgba(217,119,6,0.3)}
.badge-green{background:rgba(34,197,94,0.15);color:#4ade80;border:1px solid rgba(34,197,94,0.25)}
.badge-red{background:rgba(239,68,68,0.15);color:#f87171;border:1px solid rgba(239,68,68,0.25)}

/* ── BUTTONS ── */
.btn{display:inline-flex;align-items:center;gap:7px;padding:9px 20px;border-radius:var(--radius-md);font-size:0.9rem;font-weight:600;cursor:pointer;border:none;text-decoration:none;transition:all .2s;font-family:inherit}
.btn-primary{background:var(--blue-primary);color:#fff}
.btn-primary:hover{background:#1d4ed8;transform:translateY(-1px);box-shadow:0 6px 20px var(--blue-glow)}
.btn-secondary{background:var(--bg-card);color:var(--text-secondary);border:1px solid var(--border-color)}
.btn-secondary:hover{background:var(--bg-card-hover);color:var(--text-primary);border-color:var(--blue-border)}
.btn-ghost{background:transparent;color:var(--text-secondary);border:1px solid var(--border-color)}
.btn-ghost:hover{color:var(--text-primary);background:var(--bg-card)}
.btn-gold{background:var(--gold-primary);color:#fff}
.btn-gold:hover{background:#b45309;transform:translateY(-1px)}
.btn-sm{padding:6px 14px;font-size:0.82rem}
.btn-lg{padding:12px 28px;font-size:1rem}

/* ── LESSON HERO ── */
.lesson-hero{padding:40px 24px 0;background:radial-gradient(ellipse 70% 60% at 50% 0%,rgba(30,64,175,0.15) 0%,transparent 70%)}
.lesson-hero-inner{max-width:1280px;margin:0 auto}
.breadcrumb{display:flex;align-items:center;gap:8px;font-size:0.82rem;color:var(--text-muted);margin-bottom:20px}
.breadcrumb a{color:var(--text-secondary);text-decoration:none}
.breadcrumb a:hover{color:var(--text-primary)}
.breadcrumb-sep{color:var(--text-muted)}
.lesson-title-wrap{display:flex;align-items:flex-start;gap:20px;padding-bottom:0}
.lesson-big-icon{font-size:3rem;flex-shrink:0;margin-top:4px}
.lesson-title{font-size:clamp(1.5rem,3.5vw,2.2rem);font-weight:800;letter-spacing:-0.02em;margin-bottom:6px}
.lesson-subtitle{color:var(--text-secondary);font-size:0.95rem}
.lesson-meta{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}

/* ── TABS ── */
.content-wrap{max-width:1280px;margin:0 auto;padding:0 24px 48px}
.content-tabs{display:flex;gap:2px;border-bottom:2px solid var(--border-color);margin-bottom:32px;overflow-x:auto;padding-top:32px}
.tab-btn{background:none;border:none;color:var(--text-muted);padding:10px 20px;font-size:0.9rem;font-weight:600;cursor:pointer;border-bottom:3px solid transparent;margin-bottom:-2px;white-space:nowrap;transition:all .2s;font-family:inherit}
.tab-btn:hover{color:var(--text-secondary)}
.tab-btn.active{color:var(--gold-light);border-bottom-color:var(--gold-primary)}
.tab-panel{display:none}
.tab-panel.active{display:block}

/* ── THEORY CONTENT ── */
.theory-block{margin-bottom:36px}
.theory-block h2{font-size:1.3rem;font-weight:700;color:var(--blue-light);margin-bottom:8px}
.theory-block .intro{font-size:1rem;color:var(--text-secondary);margin-bottom:16px;line-height:1.7}
.theory-block .body-text{color:var(--text-primary);line-height:1.8;font-size:0.95rem}
.info-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;margin:18px 0}
.info-card{background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:16px}
.info-card h4{font-size:0.85rem;font-weight:700;color:var(--gold-light);margin-bottom:6px;text-transform:uppercase;letter-spacing:.04em}
.info-card p{font-size:0.83rem;color:var(--text-secondary);line-height:1.5}
.key-formula{background:rgba(30,64,175,0.1);border:1px solid var(--blue-border);border-radius:var(--radius-md);padding:16px 20px;margin:16px 0;font-family:'JetBrains Mono',monospace;font-size:0.9rem;color:var(--gold-light)}
.key-formula strong{color:var(--blue-light)}
.tip-box{background:rgba(217,119,6,0.08);border-left:4px solid var(--gold-primary);border-radius:0 var(--radius-md) var(--radius-md) 0;padding:14px 18px;margin:16px 0;font-size:0.88rem;color:var(--text-primary)}
.tip-box strong{color:var(--gold-light)}
.analogy-box{background:rgba(30,64,175,0.08);border-left:4px solid var(--blue-light);border-radius:0 var(--radius-md) var(--radius-md) 0;padding:14px 18px;margin:16px 0;font-size:0.88rem;color:var(--text-primary);font-style:italic}
.analogy-box strong{color:var(--blue-light);font-style:normal}
.eco-table{width:100%;border-collapse:collapse;margin:16px 0;font-size:0.88rem}
.eco-table th{background:rgba(30,64,175,0.2);color:var(--blue-light);padding:10px 14px;text-align:left;font-weight:600;border:1px solid var(--border-color)}
.eco-table td{padding:9px 14px;border:1px solid var(--border-color);color:var(--text-secondary)}
.eco-table tr:nth-child(even) td{background:rgba(255,255,255,0.02)}

/* ── DEMO & CALC ── */
.demo-container{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:20px;margin-bottom:20px}
.demo-container h3{font-size:1rem;font-weight:700;color:var(--blue-light);margin-bottom:14px}
.demo-controls{display:flex;flex-wrap:wrap;gap:12px;margin-bottom:16px;align-items:center}
.demo-controls label{font-size:0.82rem;color:var(--text-secondary);display:flex;flex-direction:column;gap:4px}
.demo-controls select,.demo-controls input[type=range]{background:var(--bg-input);border:1px solid var(--border-color);color:var(--text-primary);padding:6px 10px;border-radius:var(--radius-sm);font-size:0.85rem;font-family:inherit;cursor:pointer}
canvas.eco-canvas{width:100%;border-radius:var(--radius-md);display:block;background:var(--bg-secondary)}
.calc-form{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:24px;margin-bottom:20px}
.calc-form h3{font-size:1rem;font-weight:700;color:var(--blue-light);margin-bottom:16px}
.calc-row{display:flex;flex-wrap:wrap;gap:12px;align-items:flex-end;margin-bottom:12px}
.calc-row label{font-size:0.82rem;color:var(--text-secondary);display:flex;flex-direction:column;gap:4px;flex:1;min-width:140px}
.calc-row input{background:var(--bg-input);border:1px solid var(--border-color);color:var(--text-primary);padding:8px 12px;border-radius:var(--radius-sm);font-size:0.9rem;width:100%;font-family:inherit}
.calc-row input:focus{outline:none;border-color:var(--blue-border)}
.calc-result{background:rgba(30,64,175,0.1);border:1px solid var(--blue-border);border-radius:var(--radius-md);padding:14px 18px;margin-top:12px;font-family:'JetBrains Mono',monospace;font-size:0.9rem;color:var(--gold-light);min-height:44px}

/* ── QUIZ ── */
.quiz-counter{display:flex;justify-content:space-between;align-items:center;margin-bottom:10px;font-size:0.85rem;color:var(--text-secondary)}
.score-badge{background:rgba(217,119,6,0.15);border:1px solid rgba(217,119,6,0.3);color:var(--gold-light);padding:3px 10px;border-radius:99px;font-weight:600}
.quiz-progress-bar{height:6px;background:var(--bg-card);border-radius:3px;overflow:hidden;margin-bottom:20px}
.quiz-progress-fill{height:100%;background:linear-gradient(90deg,var(--blue-primary),var(--gold-primary));border-radius:3px;transition:width .4s}
.question-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:24px;margin-bottom:16px}
.q-number{font-size:0.78rem;font-weight:600;color:var(--text-muted);text-transform:uppercase;letter-spacing:.06em;margin-bottom:10px}
.q-text{font-size:1rem;font-weight:600;color:var(--text-primary);line-height:1.6;margin-bottom:16px}
.q-latex{margin:12px 0;color:var(--blue-light)}
.options-grid{display:flex;flex-direction:column;gap:8px}
.option-btn{display:flex;align-items:center;gap:12px;background:var(--bg-secondary);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:12px 16px;color:var(--text-secondary);font-size:0.9rem;cursor:pointer;text-align:left;transition:all .2s;width:100%;font-family:inherit}
.option-btn:hover:not(:disabled){background:var(--bg-card-hover);border-color:var(--blue-border);color:var(--text-primary)}
.option-letter{width:28px;height:28px;border-radius:50%;background:rgba(30,64,175,0.15);border:1px solid var(--blue-border);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:0.82rem;color:var(--blue-light);flex-shrink:0}
.option-btn.correct{background:rgba(34,197,94,0.12);border-color:rgba(34,197,94,0.4);color:#4ade80}
.option-btn.wrong{background:rgba(239,68,68,0.1);border-color:rgba(239,68,68,0.35);color:#f87171}
.explanation-box{background:rgba(30,64,175,0.08);border:1px solid var(--blue-border);border-radius:var(--radius-md);padding:14px 18px;font-size:0.88rem;color:var(--text-secondary);display:none;margin-top:14px;line-height:1.6}
.explanation-box.show{display:block}
.quiz-nav{display:flex;justify-content:space-between;align-items:center}
.results-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-xl);padding:48px 32px;text-align:center}
.result-emoji{font-size:3.5rem;display:block;margin-bottom:16px}
.result-score-big{font-size:3.5rem;font-weight:800;color:var(--gold-light);margin-bottom:8px}
.result-msg{color:var(--text-secondary);margin-bottom:24px;font-size:0.95rem}

/* ── PROGRESS ── */
.progress-overview{display:grid;grid-template-columns:repeat(auto-fill,minmax(140px,1fr));gap:16px;margin-bottom:36px}
.prog-stat{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:20px;text-align:center}
.prog-stat-num{font-size:2rem;font-weight:800;color:var(--gold-light)}
.prog-stat-label{font-size:0.75rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em;margin-top:4px}
.progress-history{list-style:none;display:flex;flex-direction:column;gap:10px}
.history-item{display:flex;align-items:center;gap:14px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:14px 18px;flex-wrap:wrap}
.history-topic{font-weight:600;color:var(--text-primary);font-size:0.9rem}
.history-score{margin-left:auto;font-weight:700;color:var(--gold-light);font-size:0.9rem;display:flex;align-items:center;gap:6px}
.history-date{font-size:0.78rem;color:var(--text-muted)}

/* ── TOOLS ── */
#lessonTabs{max-width:1280px;margin:0 auto;padding:0 24px 48px}
.tool-section{margin-bottom:28px}
.tool-section h3{font-size:1rem;font-weight:700;color:var(--gold-light);margin-bottom:14px;display:flex;align-items:center;gap:8px}

/* ── NAV FOOTER ── */
.grid-nav{display:flex;justify-content:space-between;align-items:center;margin-top:32px;padding-top:20px;border-top:1px solid var(--border-color);font-size:0.88rem}
.grid-nav a{color:var(--text-secondary);text-decoration:none;transition:color .2s}
.grid-nav a:hover{color:var(--text-primary)}

/* ── FOOTER ── */
.site-footer{background:var(--bg-secondary);border-top:1px solid var(--border-color);padding:32px 24px;text-align:center;margin-top:auto}

/* ── DOTS ── */
.dots{display:flex;gap:6px;justify-content:center;margin-top:12px}
.dot{width:8px;height:8px;border-radius:50%;background:var(--bg-card);border:1px solid var(--border-color);cursor:pointer;transition:all .2s}
.dot.active{background:var(--gold-primary);border-color:var(--gold-primary)}

@media(max-width:640px){
  .hero{padding:48px 16px 40px}
  .section{padding:40px 16px}
  .lesson-hero{padding:24px 16px 0}
  .content-wrap{padding:0 16px 32px}
  .history-item{flex-wrap:wrap;gap:8px}
  .history-score{margin-left:0}
}