:root {
    --primary: #2563eb; --primary-hover: #1d4ed8; --bg-main: #f8fafc; --bg-sidebar: #ffffff;
    --card-bg: #ffffff; --text-main: #0f172a; --text-muted: #64748b; --border: #e2e8f0;
    --success: #22c55e; --danger: #ef4444; --warning: #f59e0b; --locked-bg: #f1f5f9; --locked-text: #94a3b8;
}
body.dark-mode {
    --primary: #3b82f6; --primary-hover: #60a5fa; --bg-main: #0f172a; --bg-sidebar: #1e293b;
    --card-bg: #1e293b; --text-main: #f8fafc; --text-muted: #94a3b8; --border: #334155;
    --locked-bg: #0f172a; --locked-text: #475569;
}

body { font-family: 'Inter', sans-serif; background-color: var(--bg-main); color: var(--text-main); margin: 0; transition: background-color 0.3s, color 0.3s; overflow-x: hidden; }

/* HOMEPAGE */
.home-layout { display: none; flex-direction: column; min-height: 100vh; padding: 2rem 5%; animation: fadeIn 0.5s ease; }
.home-layout.active { display: flex; }
.home-header { display: flex; justify-content: space-between; align-items: center; width: 100%; margin-bottom: 2rem; }
.home-content { text-align: center; flex-grow: 1; display: flex; flex-direction: column; align-items: center; justify-content: center; }

.subject-hero-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1.5rem; width: 100%; max-width: 1200px; }
@media (max-width: 900px) { .subject-hero-grid { grid-template-columns: repeat(2, 1fr); } }

.subject-hero-card { background: var(--card-bg); border: 2px solid var(--border); border-radius: 20px; padding: 2.5rem 1rem; cursor: pointer; transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275); box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1); }
.subject-hero-card:hover { transform: translateY(-10px) scale(1.02); box-shadow: 0 20px 25px -5px rgba(0,0,0,0.15); border-color: var(--primary); }
.subject-hero-card .icon { font-size: 3.5rem; margin-bottom: 1rem; }
.subject-hero-card h2 { margin: 0; font-size: 1.5rem; color: var(--text-main); }
.card-maths:hover { border-color: #3b82f6; } .card-english:hover { border-color: #f59e0b; } .card-science:hover { border-color: #10b981; } .card-spanish:hover { border-color: #ef4444; }

/* App Layout */
.app-layout { display: flex; min-height: 100vh; animation: fadeIn 0.5s ease; }
.sidebar { width: 280px; background-color: var(--bg-sidebar); border-right: 1px solid var(--border); padding: 2rem; display: flex; flex-direction: column; transition: background-color 0.3s, border-color 0.3s; }
.logo { font-size: 1.8rem; font-weight: 800; color: var(--primary); margin-bottom: 3rem; transition: all 0.3s;}
.nav-menu { display: flex; flex-direction: column; gap: 1rem; flex-grow: 1; }
.nav-btn { background: transparent; border: none; color: var(--text-muted); text-align: left; padding: 1rem; font-size: 1.1rem; font-weight: 600; border-radius: 8px; cursor: pointer; transition: all 0.2s; }
.nav-btn:hover, .nav-btn.active { background: var(--primary); color: white; }
.theme-toggle button { width: 100%; padding: 1rem; background: var(--bg-main); color: var(--text-main); border: 1px solid var(--border); border-radius: 8px; cursor: pointer; font-weight: bold; transition: all 0.3s; }

.main-content { flex-grow: 1; display: flex; flex-direction: column; height: 100vh; overflow-y: auto;}
.topbar { padding: 1.5rem 3rem; display: flex; justify-content: flex-end; align-items: center; border-bottom: 1px solid var(--border); background-color: var(--card-bg); position: sticky; top: 0; z-index: 10; transition: background-color 0.3s, border-color 0.3s;}

.user-profile { display: flex; align-items: center; gap: 0.5rem; background: var(--bg-main); padding: 0.5rem 1rem; border-radius: 20px; border: 1px solid var(--border); font-weight: bold; cursor: pointer; transition: all 0.2s; color: var(--text-main);}
.user-profile:hover { border-color: var(--primary); transform: translateY(-1px); }
.user-profile.logged-in { background: #e0e7ff; color: var(--primary); border-color: var(--primary); }
body.dark-mode .user-profile.logged-in { background: rgba(37, 99, 235, 0.2); color: #93c5fd; }

.stats { display: flex; gap: 1rem; }
.stat-badge { background: var(--bg-main); padding: 0.5rem 1rem; border-radius: 20px; font-weight: bold; border: 1px solid var(--border); color: var(--text-main); transition: all 0.3s; }
.content-area { padding: 3rem; max-width: 900px; margin: 0 auto; width: 100%; }

.screen { display: none; }
.screen.active { display: block; animation: fadeIn 0.4s ease; }
.category-header { color: var(--text-muted); border-bottom: 2px solid var(--border); padding-bottom: 0.5rem; margin-bottom: 1rem; margin-top: 2rem;}

.task-card { background: var(--card-bg); border: 1px solid var(--border); padding: 1.5rem; border-radius: 12px; margin-bottom: 1rem; display: flex; justify-content: space-between; align-items: center; transition: all 0.3s;}
.task-card.locked { background: var(--locked-bg); border-style: dashed; opacity: 0.7;}
.task-desc { margin: 0; color: var(--text-muted); font-size: 0.95rem; margin-top: 0.3rem;}
.btn-locked { background: var(--locked-bg); color: var(--locked-text); border: 2px solid var(--locked-text); padding: 0.8rem 1.5rem; font-weight: bold; border-radius: 8px; cursor: not-allowed;}

/* Buttons */
.btn-primary { background: var(--primary); color: white; border: none; padding: 0.8rem 1.5rem; font-weight: bold; border-radius: 8px; cursor: pointer; transition: background 0.2s;}
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: transparent; color: var(--primary); border: 2px solid var(--primary); padding: 0.8rem 1.5rem; font-weight: bold; border-radius: 8px; cursor: pointer; transition: all 0.2s; }
.btn-secondary:hover { background: var(--primary); color: white; }
.btn-warning { background: #eab308; color: white; border: none; padding: 0.8rem 1.5rem; font-weight: bold; border-radius: 8px; cursor: pointer; transition: background 0.2s;}
.btn-warning:hover { background: #ca8a04; }
.btn-text { background: none; border: none; color: var(--text-muted); text-decoration: underline; cursor: pointer; font-size: 1rem; padding: 0.5rem; }
.btn-text:hover { color: var(--text-main); }
.btn-stuck { background: rgba(37, 99, 235, 0.1); color: var(--primary); border: none; padding: 0.8rem 1.5rem; font-weight: bold; border-radius: 8px; cursor: pointer; transition: all 0.2s; width: 100%; margin-top: 1rem; font-size: 1.1rem;}
.btn-stuck:hover { background: rgba(37, 99, 235, 0.2); }

.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; }
.topic-card { background: var(--card-bg); border: 2px solid var(--border); padding: 1rem; font-size: 1.1rem; font-weight: bold; border-radius: 12px; cursor: pointer; color: var(--text-main); transition: all 0.2s;}
.topic-card:hover { border-color: var(--primary); transform: translateY(-2px); box-shadow: 0 4px 6px rgba(0,0,0,0.05);}

.input-area { display: flex; gap: 1rem; margin-top: 1rem; }
input[type="text"], input[type="password"], input[type="number"], select { padding: 1rem; font-size: 1.2rem; border: 2px solid var(--border); border-radius: 8px; background: var(--card-bg); color: var(--text-main); outline: none; width: 100%; transition: all 0.3s;}
input:focus, select:focus { border-color: var(--primary); }

.builder-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 1rem; margin-top: 1rem; }
.checkbox-label { background: var(--card-bg); border: 2px solid var(--border); padding: 1rem; border-radius: 8px; font-weight: bold; cursor: pointer; display: flex; align-items: center; gap: 0.5rem; font-size: 0.9rem; transition: all 0.3s;}
.exam-question-card { background: var(--card-bg); border: 1px solid var(--border); border-left: 5px solid var(--primary); padding: 2rem; margin-bottom: 2rem; border-radius: 8px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); transition: all 0.3s;}
.exam-q-header { display: flex; justify-content: space-between; font-weight: bold; color: var(--text-muted); margin-bottom: 1rem; border-bottom: 1px solid var(--border); padding-bottom: 0.5rem;}

.progress-bar-container { width: 100%; height: 10px; background-color: var(--border); border-radius: 5px; margin-bottom: 2rem; overflow: hidden; }
.progress-bar { height: 100%; background-color: var(--primary); width: 0%; transition: width 0.3s ease; }
.question-text { font-size: 1.8rem; margin-bottom: 1rem; color: var(--text-main); }

.streak-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; display: flex; justify-content: center; align-items: center; z-index: 9999; opacity: 0; visibility: hidden; }
.streak-text { font-size: 5rem; font-weight: 900; color: #fbbf24; text-shadow: 0 0 15px #f59e0b, 0 0 30px #ef4444, 0 5px 10px rgba(0,0,0,0.5); transform: scale(0.8); opacity: 0; text-align: center; line-height: 1.1; margin: 0; font-family: Impact, sans-serif; letter-spacing: 2px; will-change: transform, opacity; }
.streak-overlay.animate-streak { visibility: visible; opacity: 1; }
.streak-overlay.animate-streak .streak-text { animation: epicCrispStreak 2.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards; }
@keyframes epicCrispStreak { 0% { transform: scale(0.5) translateY(50px) rotate(-5deg); opacity: 0; } 15% { transform: scale(1.1) translateY(0) rotate(5deg); opacity: 1; } 30% { transform: scale(1) translateY(0) rotate(-3deg); opacity: 1; } 80% { transform: scale(1) translateY(0) rotate(0); opacity: 1; } 100% { transform: scale(1.5) translateY(-50px); opacity: 0; } }

/* Feedback Animations */
.feedback-box { font-weight: bold; font-size: 1.2rem; margin-top: 1.5rem; min-height: 2rem; opacity: 0; }
@keyframes popIn { 0% { transform: scale(0.9); opacity: 0; } 50% { transform: scale(1.05); opacity: 1;} 100% { transform: scale(1); opacity: 1; } }
@keyframes shakePulse { 0% { transform: translateX(0); opacity: 1;} 20%, 60% { transform: translateX(-5px); opacity: 1;} 40%, 80% { transform: translateX(5px); opacity: 1;} 100% { transform: translateX(0); opacity: 1;} }

.feedback-box.correct { opacity: 1; color: var(--success); background: rgba(34, 197, 94, 0.1); padding: 1rem; border-radius: 8px; border-left: 4px solid var(--success); animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards; }
.feedback-box.incorrect { opacity: 1; color: var(--danger); background: rgba(239, 68, 68, 0.1); padding: 1rem; border-radius: 8px; border-left: 4px solid var(--danger); animation: shakePulse 0.4s ease-in-out forwards; }
.feedback-box.warning { opacity: 1; color: #b45309; background: #fef08a; padding: 1rem; border-radius: 8px; border-left: 4px solid var(--warning); animation: popIn 0.5s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards; }

.calc-badge { background: #e2e8f0; color: #475569; padding: 0.5rem 1rem; border-radius: 8px; font-weight: bold; font-size: 0.9rem; transition: all 0.3s; }
.calc-badge.active { background: #dcfce7; color: #166534; }

.modal-overlay { opacity: 0; visibility: hidden; position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.6); backdrop-filter: blur(4px); display: flex; justify-content: center; align-items: center; z-index: 1000; transition: opacity 0.3s ease, visibility 0.3s ease;}
.modal-overlay.show { opacity: 1; visibility: visible; }
.modal-content { background: var(--card-bg); padding: 2.5rem; border-radius: 16px; width: 90%; max-width: 400px; text-align: center; box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.2); transform: translateY(-30px); transition: transform 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275), background-color 0.3s;}
.modal-overlay.show .modal-content { transform: translateY(0); }
.modal-buttons { display: flex; flex-direction: column; gap: 1rem; margin-top: 1.5rem; }

.onboarding-container { position: relative; overflow: hidden; min-height: 350px;}
.onboarding-slide { position: absolute; top: 0; left: 0; width: 100%; height: 100%; opacity: 0; transform: translateX(50px); pointer-events: none; transition: all 0.4s ease; padding: 2.5rem; box-sizing: border-box; display: flex; flex-direction: column; justify-content: center;}
.onboarding-slide.active { opacity: 1; transform: translateX(0); pointer-events: auto; position: relative;}

.tree-container { display: flex; justify-content: space-between; gap: 1rem; margin-top: 2rem; flex-wrap: wrap;}
.tree-pillar { flex: 1; min-width: 150px; background: var(--card-bg); border: 2px solid var(--border); border-radius: 12px; padding: 1rem; display: flex; flex-direction: column; align-items: center; transition: all 0.3s;}
.tree-pillar h3 { margin-top: 0; font-size: 1.1rem; color: var(--text-muted); border-bottom: 2px solid var(--border); padding-bottom: 0.5rem; width: 100%; text-align: center;}
.tree-node { background: #94a3b8; color: white; padding: 0.8rem 1rem; border-radius: 20px; font-weight: bold; cursor: pointer; transition: transform 0.2s; margin: 0.5rem 0; width: 90%; text-align: center; font-size: 0.9rem;}
.tree-node:hover { transform: scale(1.05); }
.node-weak { background: var(--danger); }
.node-okay { background: var(--warning); }
.node-strong { background: var(--success); }

.support-area { margin-top: 1.5rem; text-align: left; background: var(--bg-main); border-radius: 8px; padding: 1.5rem; border: 2px solid var(--primary); display: none; animation: fadeIn 0.4s ease; transition: all 0.3s;}
.support-step { margin-bottom: 0.8rem; padding-left: 1rem; border-left: 4px solid var(--primary); font-size: 1.1rem;}

/* MINIGAME */
.mg-arcade-box { background: #0f172a; padding: 3rem; border-radius: 16px; border: 4px solid #1e293b; box-shadow: 0 10px 30px rgba(0,0,0,0.5); }
.mg-timer-track { width: 100%; height: 12px; background: #334155; border-radius: 6px; margin-bottom: 1rem; overflow: hidden; }
.mg-timer-fill { height: 100%; background: #38bdf8; width: 100%; transition: width 1s linear, background-color 0.5s; }
.mg-question-text { font-size: 2rem; color: white; margin: 0; animation: popIn 0.3s ease-out; }
.mg-btn { border: none; border-bottom: 6px solid; border-radius: 12px; padding: 1.5rem 3rem; font-size: 1.8rem; font-weight: 900; color: white; cursor: pointer; transition: all 0.1s; text-transform: uppercase; }
.mg-btn:active { transform: translateY(4px); border-bottom-width: 2px; }
.mg-true { background: #22c55e; border-color: #166534; }
.mg-false { background: #ef4444; border-color: #991b1b; }

/* AI Tutor Steps Animation */
.ai-step-anim { animation: fadeIn 0.5s ease forwards; }

.calculator-body { background: #1e293b; padding: 1.5rem; border-radius: 12px; box-shadow: inset 0 2px 4px rgba(0,0,0,0.5); }
.calc-display { background: #0f172a; color: #38bdf8; font-family: monospace; font-size: 2rem; text-align: right; padding: 1rem; border-radius: 8px; margin-bottom: 1rem; overflow: hidden; text-overflow: ellipsis; }
.calc-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0.5rem; }
.calc-btn { background: #334155; color: white; border: none; padding: 1rem; font-size: 1.2rem; font-weight: bold; border-radius: 6px; cursor: pointer; transition: background 0.1s; }
.calc-btn:hover { background: #475569; }
.calc-btn:active { transform: scale(0.95); }
.calc-op { background: var(--primary); }
.calc-op:hover { background: var(--primary-hover); }
.calc-action { background: var(--danger); }
.calc-action:hover { background: #dc2626; }
.calc-equal { background: var(--success); }
.calc-equal:hover { background: #16a34a; }

/* DRAG AND DROP */
.dnd-row { display: flex; justify-content: space-between; align-items: center; background: var(--card-bg); padding: 1rem; border-radius: 8px; border: 1px solid var(--border); font-size: 1.1rem; color: var(--text-main);}
.drop-zone { width: 180px; height: 50px; border: 2px dashed var(--primary); border-radius: 8px; display: flex; align-items: center; justify-content: center; background: var(--bg-main); transition: background 0.2s;}
.drop-zone.hover { background: #e0e7ff; }
.drag-chip { padding: 0.6rem 1.2rem; background: var(--primary); color: white; border-radius: 20px; cursor: grab; font-weight: bold; font-size: 1rem; user-select: none; box-shadow: 0 4px 6px rgba(0,0,0,0.1);}
.drag-chip:active { cursor: grabbing; }

@keyframes fadeIn { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: translateY(0); } }