/* ── Year 9 Science Unit 4: Waves & Motion ── */
/* Theme: Wave — purple, violet, indigo spectrum */

:root {
  --hero-purple:#6d28d9;
  --hero-violet:#7c3aed;
  --hero-grad:linear-gradient(135deg,#6d28d9 0%,#7c3aed 50%,#4f46e5 100%);
  --mint:#f5f3ff;
  --mint-border:#c4b5fd;
  --sky:#ede9fe;
  --sky-border:#a78bfa;
  --peach:#faf5ff;
  --peach-border:#d8b4fe;
  --teal:#5b21b6;
  --teal-mid:#7c3aed;
  --teal-light:rgba(124,58,237,.08);
  --accent-coral:#db2777;
  --accent-amber:#f59e0b;
  --purple:#7c3aed;
  --purple-light:rgba(124,58,237,.07);
  --bg:#faf5ff;
  --surface:#ffffff;
  --text:#0f172a;
  --text-muted:#475569;
  --text-light:#94a3b8;
  --border:#cbd5e1;
  --radius:14px;
  --radius-sm:8px;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0;}
body{font-family:'DM Sans',sans-serif;background:var(--bg);color:var(--text);line-height:1.65;}
h1,h2,h3,h4{font-family:'Nunito',sans-serif;}
.mono,code{font-family:'DM Mono',monospace;}

/* Progress bar */
.progress-bar-wrap{position:fixed;top:0;left:0;right:0;height:3px;background:rgba(0,0,0,.08);z-index:1000;}
.progress-bar-fill{height:100%;background:linear-gradient(90deg,var(--hero-purple),var(--hero-violet));width:0;transition:width .2s;}

/* Section nav dots */
.section-nav{position:fixed;right:14px;top:50%;transform:translateY(-50%);display:flex;flex-direction:column;gap:8px;z-index:999;}
.section-dot{width:9px;height:9px;border-radius:50%;background:#cbd5e1;cursor:pointer;transition:all .2s;position:relative;}
.section-dot.active{background:var(--hero-purple);transform:scale(1.4);}
.section-dot:hover::after{content:attr(data-label);position:absolute;right:16px;top:50%;transform:translateY(-50%);background:#0f172a;color:white;font-size:11px;font-family:'DM Sans',sans-serif;padding:3px 8px;border-radius:4px;white-space:nowrap;pointer-events:none;}

/* Page */
.page{max-width:900px;margin:0 auto;padding:40px 20px 80px;}

/* Hero */
.hero{background:var(--hero-grad);border-radius:var(--radius);padding:40px 44px;margin-bottom:28px;color:white;}
.hero-top{display:flex;align-items:flex-start;gap:24px;justify-content:space-between;}
.hero-badge-row{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px;}
.hbadge{padding:4px 12px;border-radius:100px;font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:.6px;}
.hbadge-teal{background:rgba(255,255,255,.25);color:white;}
.hbadge-outline{border:1.5px solid rgba(255,255,255,.5);background:transparent;color:rgba(255,255,255,.92);}
.hero h1{font-size:34px;font-weight:800;line-height:1.15;margin-bottom:12px;letter-spacing:-.3px;color:white;}
.hero-desc{font-size:16px;max-width:700px;line-height:1.65;opacity:.93;color:white;}
.hero-emoji{font-size:64px;line-height:1;flex-shrink:0;opacity:.8;}

/* Phase strip */
.phase-strip{display:flex;align-items:center;justify-content:center;gap:10px;margin:4px 0 22px;flex-wrap:wrap;}
.phase-step{display:flex;align-items:center;gap:8px;border:1px solid var(--border);background:#fff;border-radius:999px;padding:9px 14px;cursor:pointer;font-weight:700;color:var(--text-muted);}
.phase-step.active{background:var(--hero-purple);border-color:var(--hero-purple);color:#fff;}
.ps-num{width:22px;height:22px;border-radius:50%;display:grid;place-items:center;background:rgba(255,255,255,.18);font-size:12px;font-weight:800;}
.phase-step:not(.active) .ps-num{background:var(--teal-light);color:var(--teal);}
.ps-connector{width:28px;height:2px;background:var(--border);}
.phase{display:none;}
.phase.active{display:block;}

/* Phase buttons */
.phase-footer{text-align:center;margin:28px 0;}
.phase-back-row{margin-bottom:20px;}
.phase-back-btn{background:white;border:1.5px solid var(--border);border-radius:8px;padding:10px 18px;font-size:13px;font-weight:700;color:var(--text-muted);cursor:pointer;}
.phase-back-btn:hover{border-color:#7c3aed;color:#7c3aed;}
.phase-next-btn{display:inline-block;background:var(--hero-purple);color:white;border:none;border-radius:10px;padding:12px 24px;font-size:14px;font-weight:700;cursor:pointer;}
.phase-next-btn:hover{background:#6d28d9;}
.phase-retry-btn{display:inline-block;background:white;color:#7c3aed;border:1.5px solid #c4b5fd;border-radius:10px;padding:12px 24px;font-size:14px;font-weight:700;cursor:pointer;}
.phase-retry-btn:hover{background:#f5f3ff;}

/* Mode banner */
.mode-banner{background:white;border:1px solid var(--border);border-radius:var(--radius-sm);padding:14px 20px;margin-bottom:24px;display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;}
.mode-banner p{font-size:14px;color:var(--text-muted);}
.mode-toggle{display:flex;gap:8px;}
.mode-btn{padding:7px 16px;border-radius:6px;border:1.5px solid var(--border);background:white;font-size:13px;font-weight:700;cursor:pointer;color:var(--text-muted);transition:all .2s;}
.mode-btn.active{background:var(--hero-purple);color:white;border-color:var(--hero-purple);}

/* Think First */
.think-first{background:linear-gradient(135deg,#4c1d95 0%,#5b21b6 100%);border-radius:var(--radius);padding:32px;margin-bottom:24px;}
.tf-label{font-size:10px;font-weight:800;text-transform:uppercase;letter-spacing:1.5px;background:rgba(255,255,255,.18);display:inline-block;padding:4px 10px;border-radius:100px;margin-bottom:14px;color:white;font-family:'DM Sans',sans-serif;}
.think-first h3{font-family:'Nunito',sans-serif;color:white;font-size:17px;margin-bottom:12px;font-weight:800;}
.think-first p{color:rgba(255,255,255,.92);font-size:15px;line-height:1.7;margin-bottom:14px;}
.think-first ul{color:rgba(255,255,255,.9);font-size:15px;line-height:1.7;padding-left:18px;margin-bottom:14px;}
.think-first .answer-textarea{background:rgba(255,255,255,.08);border-color:rgba(255,255,255,.24);color:white;}
.think-first .answer-textarea::placeholder{color:rgba(255,255,255,.55);}

/* Worksheet download */
.worksheet-download-card{background:#f5f3ff;border:1px solid #ddd6fe;border-radius:12px;padding:20px 24px;margin-bottom:24px;display:flex;align-items:center;gap:18px;}
.worksheet-download-eyebrow{font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:1.2px;color:#7c3aed;display:block;margin-bottom:6px;}
.worksheet-download-card h2{font-size:18px;margin:0 0 6px;color:#0f172a;}
.worksheet-download-card p{font-size:14px;color:#475569;margin:0;}
.worksheet-download-actions{display:flex;gap:10px;}
.btn-primary{display:inline-block;background:#7c3aed;color:white;padding:10px 18px;border-radius:8px;text-decoration:none;font-weight:700;font-size:13px;transition:all .2s;}
.btn-primary:hover{background:#6d28d9;}
.btn-ghost{display:inline-block;background:white;color:#7c3aed;padding:10px 18px;border-radius:8px;text-decoration:none;font-weight:700;font-size:13px;border:1.5px solid #c4b5fd;transition:all .2s;}
.btn-ghost:hover{background:#f5f3ff;}

/* Intentions */
.intentions-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-bottom:24px;}
.intention-card{background:white;border:1.5px solid;border-radius:var(--radius-sm);padding:20px;}
.intention-card.mint{border-color:#c4b5fd;background:#f5f3ff;}
.intention-card.sky{border-color:#a78bfa;background:#ede9fe;}
.intention-card.peach{border-color:#d8b4fe;background:#faf5ff;}
.intention-card h3{font-size:15px;margin-bottom:10px;color:#0f172a;}
.intention-card ul{padding-left:18px;font-size:14px;color:#334155;line-height:1.7;}

/* Key Terms */
.key-terms-panel{background:white;border:1.5px solid var(--border);border-radius:var(--radius);padding:24px;margin-bottom:24px;}
.kt-label{font-size:10px;font-weight:800;text-transform:uppercase;letter-spacing:1.5px;color:#7c3aed;display:block;margin-bottom:14px;}
.kt-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;}
.kt-item{background:#f8fafc;border:1px solid #e2e8f0;border-radius:8px;padding:12px 16px;}
.kt-term{font-weight:700;color:#0f172a;font-size:14px;display:block;margin-bottom:4px;}
.kt-def{color:#475569;font-size:13px;line-height:1.5;}

/* Misconceptions */
.misconceptions-box{background:white;border:1.5px solid #fecaca;border-radius:var(--radius);padding:24px;margin-bottom:24px;}
.misconceptions-box h3{font-size:16px;margin-bottom:14px;color:#7f1d1d;}
.misconception-item{display:flex;gap:12px;margin-bottom:12px;align-items:flex-start;}
.misconception-x{width:28px;height:28px;border-radius:50%;display:grid;place-items:center;font-size:14px;font-weight:800;flex-shrink:0;}
.misconception-item:nth-child(odd) .misconception-x{background:#fecaca;color:#991b1b;}
.misconception-item:nth-child(even) .misconception-x{background:#d1fae5;color:#065f46;}
.misconception-item p{font-size:14px;color:#334155;line-height:1.6;margin:0;}

/* Cards */
.card{background:white;border:1.5px solid var(--border);border-radius:var(--radius);padding:28px;margin-bottom:20px;}
.card-header{display:flex;align-items:center;gap:12px;margin-bottom:14px;}
.card-num{width:32px;height:32px;border-radius:8px;background:var(--hero-purple);color:white;display:grid;place-items:center;font-size:14px;font-weight:800;flex-shrink:0;}
.card h2{font-size:19px;margin:0;color:#0f172a;}
.card p{font-size:15px;color:#475569;line-height:1.65;margin-bottom:12px;}
.card-subtitle{color:#64748b;font-size:13px;margin-top:4px;}

/* Section label */
.section-label{font-size:10px;font-weight:800;text-transform:uppercase;letter-spacing:1.5px;color:#7c3aed;display:block;margin:28px 0 14px;}

/* Answer area */
.answer-wrap{margin-top:12px;}
.answer-textarea{width:100%;min-height:90px;padding:14px;border-radius:8px;border:1.5px solid #cbd5e1;font-size:14px;font-family:'DM Sans',sans-serif;resize:vertical;background:white;}
.answer-textarea:focus{border-color:#7c3aed;outline:none;}
.answer-book-placeholder{display:none;background:#f8fafc;border:1.5px dashed #cbd5e1;border-radius:8px;padding:14px;font-size:14px;color:#64748b;text-align:center;}
.book-mode .answer-textarea{display:none;}
.book-mode .answer-book-placeholder{display:block;}
.autosave-indicator{font-size:12px;color:#94a3b8;margin-top:6px;text-align:right;}

/* Question items */
.question-item{margin-bottom:20px;padding-bottom:16px;border-bottom:1px solid var(--border);}
.question-item:last-child{border-bottom:none;padding-bottom:0;}
.marks{font-size:13px;color:#7c3aed;font-weight:700;}

/* MCQ */
.mc-question{background:white;border:1.5px solid var(--border);border-radius:var(--radius-sm);padding:20px;margin-bottom:16px;}
.mc-question p{font-weight:600;color:#0f172a;font-size:15px;margin-bottom:12px;}
.mc-options{display:flex;flex-direction:column;gap:8px;}
.mc-option{display:flex;align-items:center;gap:10px;padding:12px 14px;border-radius:8px;border:1.5px solid #e2e8f0;cursor:pointer;transition:all .15s;background:white;}
.mc-option:hover{border-color:#a78bfa;background:#f5f3ff;}
.mc-option.disabled{cursor:default;pointer-events:none;}
.mc-option.correct{border-color:#22c55e;background:#f0fdf4;}
.mc-option.incorrect{border-color:#ef4444;background:#fef2f2;}
.mc-letter{width:28px;height:28px;border-radius:50%;background:#f1f5f9;color:#475569;display:grid;place-items:center;font-size:13px;font-weight:800;flex-shrink:0;}
.mc-option.correct .mc-letter{background:#22c55e;color:white;}
.mc-option.incorrect .mc-letter{background:#ef4444;color:white;}
.mc-text{font-size:14px;color:#334155;}
.mc-feedback{display:none;margin-top:10px;padding:12px;border-radius:8px;font-size:14px;}
.mc-feedback.correct-msg{background:#f0fdf4;color:#166534;border:1px solid #86efac;display:block;}
.mc-feedback.incorrect-msg{background:#fef2f2;color:#991b1b;border:1px solid #fca5a5;display:block;}

/* Score banner */
.mc-score-banner{display:none;padding:14px 18px;border-radius:12px;margin:16px 0;font-weight:700;text-align:center;font-size:15px;}
.mc-score-banner.pass{background:#f0fdf4;color:#166534;border:1.5px solid #86efac;}
.mc-score-banner.fail{background:#fef2f2;color:#991b1b;border:1.5px solid #fca5a5;}

/* Game */
.game-launch-card{background:linear-gradient(135deg,#f5f3ff 0%,#ede9fe 100%);border:2px solid #c4b5fd;border-radius:var(--radius);padding:28px;text-align:center;margin-bottom:24px;}
.game-launch-card h2{font-size:20px;margin-bottom:8px;color:#0f172a;}
.game-launch-card p{color:#475569;font-size:15px;margin-bottom:16px;}
.game-iframe{width:100%;height:520px;border:none;border-radius:16px;}

/* Completion */
.completion-wrap{display:flex;gap:14px;align-items:flex-start;background:white;border:1.5px solid var(--border);border-radius:var(--radius);padding:20px 24px;margin:28px 0;cursor:pointer;transition:all .2s;}
.completion-wrap:hover{border-color:#7c3aed;}
.completion-checkbox{width:28px;height:28px;border-radius:8px;border:2.5px solid #7c3aed;display:grid;place-items:center;font-weight:800;color:white;transition:all .2s;flex-shrink:0;margin-top:2px;}
.completion-checkbox.done{background:#7c3aed;}
.completion-text h4{font-size:15px;font-weight:800;color:#0f172a;margin:0 0 4px;}
.completion-text p{color:#475569;font-size:14px;margin:0;}

/* Collapsible */
.collapsible-wrap{background:white;border:1.5px solid var(--border);border-radius:var(--radius);padding:24px;margin-bottom:20px;}
.collapsible-trigger{display:flex;justify-content:space-between;align-items:center;cursor:pointer;}
.collapsible-trigger h2{font-size:18px;margin:0;color:#0f172a;}
.collapsible-arrow{font-size:14px;color:#94a3b8;transition:transform .3s;}
.collapsible-trigger.open .collapsible-arrow{transform:rotate(180deg);}
.collapsible-body{display:none;padding-top:16px;}
.collapsible-body.open{display:block;}

/* Lesson nav */
.lesson-nav{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-top:10px;}
.lesson-nav a{display:inline-flex;align-items:center;padding:12px 18px;border-radius:12px;text-decoration:none;font-weight:700;font-size:14px;border:1.5px solid #e2e8f0;background:white;color:#0f172a;transition:all .2s;}
.lesson-nav a:hover{border-color:#7c3aed;color:#7c3aed;}
.lesson-nav a.next{background:#7c3aed;border-color:#7c3aed;color:white;}
.lesson-nav a.next:hover{background:#6d28d9;}

/* Callout boxes */
.callout-box{padding:16px 20px;border-radius:10px;margin:16px 0;border-left:4px solid;}
.callout-box.mint{background:#f0fdf4;border-color:#22c55e;}
.callout-box.sky{background:#f0f9ff;border-color:#0ea5e9;}
.callout-box.peach{background:#fff7ed;border-color:#f97316;}
.callout-box h4{font-size:14px;margin-bottom:6px;}
.callout-box p{font-size:14px;color:#334155;margin:0;}

/* Revisit box */
.revisit-box{background:white;border:1.5px solid var(--border);border-radius:var(--radius);padding:24px;margin-bottom:20px;}
.revisit-box h3{font-size:16px;margin-bottom:10px;color:#0f172a;}
.revisit-box p,.revisit-box ul{font-size:14px;color:#475569;line-height:1.6;margin-bottom:10px;}
.revisit-box ul{padding-left:18px;}

/* Answer items */
.answer-item{margin-bottom:14px;}
.answer-item h4{font-size:14px;margin-bottom:6px;color:#0f172a;}
.answer-item p{font-size:14px;color:#475569;line-height:1.6;margin:0;}

/* Diagram embed */
.diagram-embed{margin:16px 0;}
.diagram-embed img{width:100%;display:block;border-radius:12px;}

/* Utility classes */
.mc-gate-btns{display:none;justify-content:center;gap:12px;margin-top:14px;}
.card-review{background:linear-gradient(135deg,#f5f3ff 0%,#ede9fe 100%);border-color:#c4b5fd;}
.card-num-purple{background:#7c3aed;}
.card-num-amber{background:#f59e0b;}
.card-num-green{background:#15803d;}
.mark-hint{font-size:13px;color:#94a3b8;font-weight:400;}
.list-clean{padding-left:20px;font-size:15px;color:#475569;line-height:1.8;margin-bottom:14px;}
.list-clean li{margin-bottom:6px;}
.copy-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:16px;}
.copy-item{background:#f8fafc;border:1px solid #e2e8f0;border-radius:10px;padding:16px;}
.copy-item h4{font-size:14px;margin-bottom:8px;color:#0f172a;}
.copy-item p{font-size:14px;color:#475569;line-height:1.6;margin:0;}
.step-box{background:#f8fafc;border:1px solid #e2e8f0;border-radius:10px;padding:16px;margin-bottom:12px;}
.step-box h4{font-size:14px;margin-bottom:6px;color:#0f172a;}
.step-box p{font-size:14px;color:#475569;line-height:1.6;margin:0;}
.game-emoji{font-size:48px;margin-bottom:12px;}
.phase-footer-center{text-align:center;margin:28px 0;}

/* Responsive */
/* Fade-up */
.fade-up{opacity:0;transform:translateY(16px);transition:opacity .5s ease,transform .5s ease;}
.fade-up.visible{opacity:1;transform:none;}

/* Phase navigation */
.phase-footer{text-align:center;margin:28px 0;}
.phase-next-btn{display:inline-flex;align-items:center;gap:8px;padding:14px 28px;border-radius:10px;background:var(--hero-violet);color:white;font-size:15px;font-weight:700;border:none;cursor:pointer;transition:background .2s;}
.phase-next-btn:hover{background:var(--hero-purple);}
.phase-back-row{margin-bottom:20px;}
.phase-back-btn{padding:10px 18px;border-radius:8px;border:1.5px solid var(--border);background:white;font-size:13px;font-weight:700;color:var(--text-muted);cursor:pointer;transition:all .2s;}
.phase-back-btn:hover{border-color:var(--hero-violet);color:var(--hero-violet);}
.phase-retry-btn{padding:10px 18px;border-radius:8px;border:1.5px solid var(--border);background:white;font-size:13px;font-weight:700;color:var(--text-muted);cursor:pointer;}

/* MC feedback display */
.mc-feedback.correct-msg{display:block;}
.mc-feedback.incorrect-msg{display:block;}

/* Score banner */
.score-banner{display:none;padding:14px 18px;border-radius:12px;margin:16px 0;font-weight:700;text-align:center;}
.score-banner.pass{background:#f0fdf4;color:#166534;border:1.5px solid #86efac;}
.score-banner.fail{background:#fef2f2;color:#991b1b;border:1.5px solid #fca5a5;}

/* Conceptual opener */
.conceptual-first{font-size:16px;color:var(--hero-violet);font-style:italic;line-height:1.65;margin-bottom:18px;padding-left:16px;border-left:3px solid var(--hero-violet);}

/* Aussie anchor */
.aussie-anchor{background:linear-gradient(135deg,#ecfdf5 0%,#fefce8 100%);border:1.5px solid #22c55e;border-radius:var(--radius);padding:20px 24px;margin:20px 0;}
.aussie-label{font-size:10px;font-weight:800;text-transform:uppercase;letter-spacing:1.2px;color:#15803d;display:block;margin-bottom:8px;}
.aussie-anchor p{color:#14532d;font-size:14px;line-height:1.65;margin:0;}
.aussie-anchor strong{color:#166534;}

/* Fun fact */
.fun-fact-box{background:linear-gradient(135deg,#fefce8 0%,#fef9c3 100%);border:1.5px solid #eab308;border-radius:var(--radius);padding:20px 24px;margin:20px 0;}
.fun-fact-label{font-size:10px;font-weight:800;text-transform:uppercase;letter-spacing:1.2px;color:#a16207;display:block;margin-bottom:8px;}
.fun-fact-box p{color:#713f12;font-size:14px;line-height:1.65;margin:0;}
.fun-fact-box strong{color:#92400e;}

/* Drill items */
.drill-item{margin-bottom:18px;padding-bottom:18px;border-bottom:1px solid var(--border);}
.drill-item:last-child{border-bottom:none;margin-bottom:0;padding-bottom:0;}
.drill-num{display:inline-flex;align-items:center;justify-content:center;width:22px;height:22px;border-radius:50%;background:var(--hero-violet);color:white;font-size:11px;font-weight:800;margin-right:6px;font-family:'Nunito',sans-serif;}

/* Interactive placeholder */
.interactive-placeholder{background:linear-gradient(135deg,#f5f3ff,#ede9fe);border:2px dashed #c4b5fd;border-radius:16px;padding:40px 28px;text-align:center;margin:20px 0;}
.interactive-placeholder h3{font-size:18px;color:var(--text);margin-bottom:8px;}
.interactive-placeholder p{color:var(--text-muted);font-size:14px;margin:0;}

/* Game launch extras */
.game-launch-icon{font-size:64px;line-height:1;filter:drop-shadow(0 4px 12px rgba(124,58,237,0.25));}
.game-launch-tag{display:inline-block;background:rgba(124,58,237,0.12);color:#6d28d9;border:1.5px solid rgba(124,58,237,0.30);border-radius:50px;padding:5px 18px;font-size:12px;font-weight:800;letter-spacing:0.12em;text-transform:uppercase;}
.game-launch-title{font-size:28px;font-weight:800;color:#4c1d95;margin:0;line-height:1.25;}
.game-launch-desc{font-size:16px;color:#475569;max-width:520px;line-height:1.65;margin:0;}

/* Worksheet copy flex */
.worksheet-download-copy{flex:1;min-width:220px;}

/* Game iframe */
.game-iframe{width:100%;height:700px;border:none;display:block;border-radius:12px;}

/* Phase gate buttons start hidden */
#phase2-retry,#phase2-continue{display:none;}

/* Formula display */
.formula-display{text-align:center;font-family:'DM Mono',monospace;font-size:22px;margin:18px 0;}

@media(max-width:768px){
  .page{padding:24px 16px 60px;}
  .hero{padding:30px 24px;}
  .hero h1{font-size:28px;}
  .hero-top{flex-direction:column;}
  .intentions-grid{grid-template-columns:1fr;}
  .kt-grid{grid-template-columns:1fr;}
  .section-nav{display:none;}
  .worksheet-download-card{flex-direction:column;align-items:flex-start;}
}