/* HK Primary English Review - Styles */
:root {
  --bg: #f8f9fa; --surface: #fff; --text: #1a1a2e;
  --text2: #555770; --text3: #8e90a6; --border: #e2e3e9;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 14px rgba(0,0,0,0.08);
  --rs: 8px; --rm: 12px; --rl: 20px;
  --font: 'Segoe UI','Noto Sans TC',system-ui,sans-serif;
  --fm: 'Cascadia Code','SF Mono',monospace;
  --nav: 64px; --accent: #4F7CFF; --ah: #3a63d4;
  --ok: #2ECC71; --no: #E74C3C; --tr: 0.2s ease;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;font-size:16px}
body{font-family:var(--font);background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh}
.navbar{position:fixed;top:0;left:0;right:0;height:var(--nav);background:rgba(255,255,255,0.92);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);border-bottom:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 24px;z-index:1000}
.navbar-brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:1.15rem;color:var(--text);text-decoration:none;cursor:pointer}
.navbar-brand .logo-icon{width:32px;height:32px;background:linear-gradient(135deg,#4F7CFF,#9B59B6);border-radius:var(--rs);display:flex;align-items:center;justify-content:center;color:#fff;font-size:.85rem;font-weight:800}
.navbar-grades{display:flex;gap:4px;align-items:center}
.nav-btn{display:flex;align-items:center;justify-content:center;width:40px;height:40px;border-radius:var(--rs);border:none;background:transparent;color:var(--text2);font-weight:600;font-size:.85rem;cursor:pointer;transition:var(--tr);font-family:var(--font)}
.nav-btn:hover{background:rgba(79,124,255,0.08);color:var(--accent)}
.nav-btn.active{background:var(--accent);color:#fff;box-shadow:0 2px 8px rgba(79,124,255,0.3)}
@media(max-width:480px){.navbar{padding:0 12px}.nav-btn{width:34px;height:34px;font-size:.75rem}.navbar-brand span{display:none}}
.hero{margin-top:var(--nav);padding:60px 24px 48px;text-align:center;background:linear-gradient(135deg,#E8EEFF,#F0E6FF 50%,#E8F8F0)}
.hero h1{font-size:2.4rem;font-weight:800;margin-bottom:8px;background:linear-gradient(135deg,#4F7CFF,#9B59B6);-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero p{font-size:1.1rem;color:var(--text2);max-width:560px;margin:0 auto}
.hero-badges{display:flex;justify-content:center;gap:10px;margin-top:16px;flex-wrap:wrap}
.hero-badge{background:#fff;padding:4px 14px;border-radius:20px;font-size:.8rem;font-weight:600;color:var(--text2);box-shadow:var(--shadow-sm)}
.main-content{max-width:960px;margin:0 auto;padding:32px 24px 80px}
.grade-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:16px;margin-bottom:40px}
.grade-card{background:var(--surface);border-radius:var(--rm);padding:20px;box-shadow:var(--shadow-sm);border:2px solid var(--border);cursor:pointer;transition:var(--tr)}
.grade-card:hover{transform:translateY(-2px);box-shadow:var(--shadow-md)}
.grade-card-header{display:flex;align-items:center;gap:10px;margin-bottom:8px}
.grade-card-header .emoji{font-size:1.5rem}.grade-card-header h3{font-size:1.1rem;font-weight:700}
.grade-card p{font-size:.9rem;color:var(--text2);margin-bottom:12px}
.grade-card-meta span{font-size:.75rem;background:var(--bg);padding:2px 10px;border-radius:12px;font-weight:600;color:var(--text3);margin-right:8px}
.level-header{display:flex;align-items:center;gap:14px;margin-bottom:24px;padding-bottom:16px;border-bottom:2px solid var(--border)}
.level-header .level-emoji{font-size:2rem}
.level-header .level-info h2{font-size:1.5rem;font-weight:700}
.level-header .level-info p{color:var(--text2);font-size:.9rem}
.back-btn{display:inline-flex;align-items:center;gap:6px;background:none;border:none;color:var(--accent);font-weight:600;cursor:pointer;font-size:.9rem;font-family:var(--font);margin-bottom:12px}
.back-btn:hover{text-decoration:underline}
.section-tabs{display:flex;gap:4px;margin-bottom:24px;background:var(--surface);border-radius:var(--rs);padding:4px;box-shadow:var(--shadow-sm);overflow-x:auto}
.section-tab{padding:8px 16px;border:none;background:transparent;border-radius:6px;font-weight:600;font-size:.85rem;color:var(--text2);cursor:pointer;transition:var(--tr);white-space:nowrap;font-family:var(--font)}
.section-tab:hover{background:rgba(79,124,255,0.06);color:var(--accent)}
.section-tab.active{background:var(--accent);color:#fff}
.grammar-card{background:var(--surface);border-radius:var(--rm);padding:24px;margin-bottom:16px;box-shadow:var(--shadow-sm);border:1px solid var(--border)}
.grammar-card h4{font-size:1.05rem;font-weight:700;margin-bottom:10px}
.grammar-card .explanation{background:#f8faff;border-left:3px solid var(--accent);padding:12px 16px;border-radius:0 var(--rs) var(--rs) 0;margin-bottom:14px;font-size:.92rem;line-height:1.7;color:var(--text);white-space:pre-line}
.grammar-card .explanation strong{color:var(--accent)}
.grammar-card .examples li{background:var(--bg);padding:6px 14px;border-radius:6px;font-size:.9rem;border:1px solid var(--border);display:inline-block;margin:4px}
.exercise-toggle{display:inline-flex;align-items:center;gap:6px;padding:8px 18px;background:var(--accent);color:#fff;border:none;border-radius:6px;font-weight:600;font-size:.85rem;cursor:pointer;font-family:var(--font)}
.exercise-toggle:hover{background:var(--ah)}
.exercise-list{margin-top:14px;display:none;flex-direction:column;gap:12px}
.exercise-list.open{display:flex}
.exercise-item{background:var(--bg);border-radius:var(--rs);padding:14px 16px;border:1px solid var(--border)}
.exercise-item .q{font-weight:600;margin-bottom:8px;font-size:.95rem}
.exercise-options{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:8px}
.exercise-options button{padding:6px 18px;border:2px solid var(--border);border-radius:6px;background:#fff;font-weight:500;font-size:.9rem;cursor:pointer;font-family:var(--font)}
.exercise-options button:hover{border-color:var(--accent);color:var(--accent)}
.exercise-options button.correct{border-color:var(--ok);background:#E8F8F0;color:#1a8a4a}
.exercise-options button.incorrect{border-color:var(--no);background:#FFE8E6;color:#c0392b}
.exercise-options button:disabled{cursor:default;opacity:.85}
.exercise-feedback{font-size:.85rem;color:var(--text2);min-height:20px}
.vocab-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:16px}
.vocab-category{background:var(--surface);border-radius:var(--rm);padding:18px;box-shadow:var(--shadow-sm);border:1px solid var(--border)}
.vocab-category h4{font-size:1rem;font-weight:700;margin-bottom:10px;padding-bottom:6px;border-bottom:2px solid var(--border)}
.vocab-category li{background:var(--bg);padding:4px 12px;border-radius:6px;font-size:.85rem;border:1px solid var(--border);display:inline-block;margin:3px}
.phonics-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(180px,1fr));gap:8px}
.phonics-item{background:var(--surface);border-radius:var(--rs);padding:12px 14px;box-shadow:var(--shadow-sm);border:1px solid var(--border);text-align:center}
.phonics-item .sound{font-weight:800;font-size:1.1rem;color:var(--accent);font-family:var(--fm)}
.phonics-item .example{font-size:.8rem;color:var(--text3);margin-top:2px}
.text-types-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:12px}
.text-type-card{background:var(--surface);border-radius:var(--rs);padding:16px;box-shadow:var(--shadow-sm);border:1px solid var(--border)}
.text-type-card h4{font-weight:700;font-size:.9rem;margin-bottom:4px}
.text-type-card p{font-size:.82rem;color:var(--text2)}
.footer{text-align:center;padding:20px 24px;font-size:.8rem;color:var(--text3);border-top:1px solid var(--border);margin-top:40px}
.footer strong{color:var(--text2)}
@keyframes fadeIn{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}
.fade-in{animation:fadeIn .3s ease forwards}
@media(max-width:640px){.hero h1{font-size:1.6rem}.grade-grid{grid-template-columns:1fr}}
@media print{.navbar,.back-btn,.exercise-toggle{display:none!important}.hero{padding:20px;margin-top:0}.exercise-list{display:flex!important}}
.spk{display:inline-flex;align-items:center;justify-content:center;width:28px;height:28px;border:none;background:#e8eeff;border-radius:50%;cursor:pointer;font-size:.8rem;margin-right:6px;transition:var(--tr);vertical-align:middle}
.spk:hover{background:var(--accent);transform:scale(1.15)}
.phonics-item .example{font-size:.8rem;color:var(--text3);margin-top:2px;display:flex;align-items:center;gap:4px;justify-content:center}
.vocab-category li{display:inline-flex;align-items:center}

/* 科目切換按鈕 */
.navbar-subjects{display:flex;gap:4px;align-items:center;margin:0 8px}
.subj-btn{display:flex;align-items:center;gap:4px;padding:6px 12px;border:none;border-radius:var(--rs);background:transparent;color:var(--text2);font-weight:600;font-size:.8rem;cursor:pointer;transition:var(--tr);font-family:var(--font);white-space:nowrap}
.subj-btn:hover{background:color-mix(in srgb,var(--subj-color,#4F7CFF) 10%,transparent);color:var(--subj-color,#4F7CFF)}
.subj-btn.active{background:var(--subj-color,#4F7CFF);color:#fff;box-shadow:0 2px 8px color-mix(in srgb,var(--subj-color,#4F7CFF) 40%,transparent)}
@media(max-width:640px){.subj-btn{font-size:.7rem;padding:4px 8px;gap:2px}.navbar-subjects{order:-1;width:100%;justify-content:center;margin:0 0 4px}}
@media(max-width:480px){.navbar{flex-wrap:wrap;height:auto;padding:8px 12px}.navbar-subjects{gap:2px}.subj-btn{font-size:.65rem;padding:3px 6px}}