/* CSS Variables & Dark Theme */
:root {
    --bg-color: #0f172a;
    --sidebar-bg: #1e293b;
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --accent-green: #10b981;
    --accent-green-hover: #059669;
    --accent-blue: #3b82f6;
    --accent-blue-hover: #2563eb;
    --accent-red: #ef4444;
    --card-bg: #334155;
    --border-color: #475569;
    --header-height: 70px;
    --sidebar-width: 300px;
}

/* Reset & Base Styles */
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Inter', system-ui, sans-serif; background-color: var(--bg-color); color: var(--text-main); display: flex; height: 100vh; overflow: hidden; }

/* Custom Scrollbar */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-color); }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

/* Header */
header { 
    position: fixed; top: 0; left: 0; right: 0; height: var(--header-height); 
    background-color: rgba(30, 41, 59, 0.95); backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color); display: flex; align-items: center; 
    padding: 0 30px; z-index: 100; justify-content: space-between; box-shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
}
.logo { font-weight: 700; color: var(--accent-green); font-size: 1.2rem; letter-spacing: 0.5px; }
.progress-container { flex: 1; margin: 0 40px; background-color: var(--bg-color); border-radius: 20px; height: 12px; overflow: hidden; border: 1px solid var(--border-color); }
.progress-bar { height: 100%; background: linear-gradient(90deg, #10b981, #3b82f6); width: 0%; transition: width 0.5s ease-in-out; }
.hamburger { display: none; background: none; border: none; color: var(--text-main); font-size: 28px; cursor: pointer; }
.btn-reset { background: none; border: none; font-size: 1.2rem; cursor: pointer; transition: transform 0.3s; opacity: 0.7; }
.btn-reset:hover { transform: rotate(-180deg); opacity: 1; }

#pomodoro-timer {
    background: var(--card-bg); border: 1px solid var(--border-color); padding: 5px 15px; border-radius: 20px;
    font-family: 'Fira Code', monospace; font-weight: bold; color: var(--text-muted); cursor: pointer; user-select: none;
    transition: all 0.3s; display: flex; align-items: center; gap: 8px; font-size: 0.95rem;
}
#pomodoro-timer:hover { background: #1e293b; color: var(--accent-red); border-color: var(--accent-red); }
#pomodoro-timer.running { color: var(--accent-red); border-color: var(--accent-red); box-shadow: 0 0 10px rgba(239, 68, 68, 0.2); }
#pomodoro-timer.break { color: var(--accent-blue); border-color: var(--accent-blue); box-shadow: 0 0 10px rgba(59, 130, 246, 0.2); }

/* Sidebar */
aside { 
    width: var(--sidebar-width); background-color: var(--sidebar-bg); height: calc(100vh - var(--header-height)); 
    margin-top: var(--header-height); border-right: 1px solid var(--border-color); 
    overflow-y: auto; padding: 20px 0; transition: transform 0.3s ease; 
}
.menu-month { padding: 15px 20px 5px; font-weight: 700; color: var(--accent-blue); text-transform: uppercase; font-size: 0.85rem; letter-spacing: 1px; }
.menu-week { 
    padding: 12px 20px 12px 40px; cursor: pointer; color: var(--text-muted); 
    transition: all 0.2s; display: flex; justify-content: space-between; align-items: center; font-size: 0.95rem; border-left: 4px solid transparent;
}
.menu-week:hover:not(.locked) { background-color: var(--card-bg); color: var(--text-main); }
.menu-week.active { background-color: var(--card-bg); color: var(--text-main); border-left-color: var(--accent-green); font-weight: 600; }
.menu-week.locked { opacity: 0.4; cursor: not-allowed; }
.menu-week.locked::after { content: "🔒"; font-size: 0.8rem; }

/* Main Content */
main { flex: 1; height: calc(100vh - var(--header-height)); margin-top: var(--header-height); padding: 50px; overflow-y: auto; scroll-behavior: smooth; }
#content-area { max-width: 800px; margin: 0 auto; line-height: 1.7; animation: fadeIn 0.4s ease-out; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(15px); } to { opacity: 1; transform: translateY(0); } }

/* Typography */
h1 { font-size: 2.2rem; margin-bottom: 10px; color: #fff; letter-spacing: -0.5px; }
h2 { font-size: 1.5rem; margin-top: 40px; margin-bottom: 20px; color: var(--accent-blue); border-bottom: 1px solid var(--border-color); padding-bottom: 10px; }
h3 { font-size: 1.2rem; margin-top: 30px; margin-bottom: 15px; color: #e2e8f0; }
p { margin-bottom: 20px; color: var(--text-muted); font-size: 1.05rem; }
ul { margin-bottom: 20px; color: var(--text-muted); padding-left: 20px; }
li { margin-bottom: 8px; }
.subtitle { color: var(--accent-green); font-weight: 600; margin-bottom: 30px; font-size: 1.1rem; }

code { background-color: #000; padding: 4px 8px; border-radius: 6px; font-family: 'Fira Code', monospace; color: var(--accent-green); font-size: 0.9rem; }
pre { background-color: #000; padding: 20px; border-radius: 10px; overflow-x: auto; margin-bottom: 25px; border: 1px solid var(--border-color); }
pre code { color: #e2e8f0; background: none; padding: 0; font-size: 0.95rem; }

/* Module Study Container */
.study-container { margin-bottom: 50px; background-color: rgba(0,0,0,0.1); padding: 30px; border-radius: 12px; border: 1px solid var(--border-color); }

/* Components: Flashcards */
.flashcards-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 20px; margin: 30px 0; }
.flashcard { perspective: 1000px; height: 160px; cursor: pointer; }
.flashcard-inner { width: 100%; height: 100%; transition: transform 0.6s cubic-bezier(0.4, 0.2, 0.2, 1); transform-style: preserve-3d; position: relative; }
.flashcard.flipped .flashcard-inner { transform: rotateY(180deg); }
.flashcard-front, .flashcard-back { 
    width: 100%; height: 100%; position: absolute; backface-visibility: hidden; 
    display: flex; align-items: center; justify-content: center; padding: 25px; text-align: center; 
    border-radius: 12px; box-shadow: 0 10px 15px -3px rgba(0,0,0,0.1); border: 1px solid var(--border-color);
}
.flashcard-front { background: linear-gradient(145deg, var(--card-bg), #2c384a); color: var(--text-main); font-weight: 600; font-size: 1.1rem; }
.flashcard-back { background: linear-gradient(145deg, var(--accent-blue), #1e40af); color: #fff; transform: rotateY(180deg); font-size: 1rem; }

/* Components: Quiz in-text */
.inline-quiz { background-color: var(--card-bg); padding: 25px; border-radius: 12px; margin: 30px 0; border-left: 5px solid var(--accent-blue); box-shadow: 0 4px 6px rgba(0,0,0,0.05); }
.inline-quiz h4 { margin-top: 0; margin-bottom: 15px; color: #fff; display: flex; align-items: center; gap: 10px; font-size: 1.1rem; }
.inline-quiz h4::before { content: "🎯"; }
.quiz-options { display: flex; flex-direction: column; gap: 12px; }
.quiz-btn { background-color: var(--bg-color); border: 1px solid var(--border-color); color: var(--text-main); padding: 15px; border-radius: 8px; cursor: pointer; text-align: left; transition: all 0.2s; font-size: 1rem; }
.quiz-btn:hover:not(:disabled) { background-color: #1e293b; border-color: var(--text-muted); }
.quiz-btn.correct { background-color: rgba(16, 185, 129, 0.15); border-color: var(--accent-green); color: var(--accent-green); font-weight: bold; }
.quiz-btn.wrong { background-color: rgba(239, 68, 68, 0.15); border-color: var(--accent-red); color: var(--accent-red); }
.quiz-feedback { margin-top: 15px; font-size: 0.95rem; display: none; padding: 15px; border-radius: 8px; line-height: 1.5; }
.quiz-feedback.show { display: block; animation: fadeIn 0.3s; }

/* Components: Memory Palace */
.memory-palace { background: linear-gradient(135deg, #4c1d95, #2e1065); padding: 30px; border-radius: 16px; margin: 40px 0; box-shadow: 0 10px 25px rgba(0,0,0,0.3); border: 1px solid #7c3aed; }
.memory-palace h2 { color: #ddd6fe; border-bottom-color: #8b5cf6; margin-top: 0; }
.memory-palace h2::before { content: "🏰 "; }
.memory-palace p, .memory-palace li { color: #eedeff; }

/* Components: Exam */
.exam-section { background: linear-gradient(to bottom right, var(--card-bg), var(--sidebar-bg)); padding: 40px; border-radius: 16px; margin-top: 50px; border: 1px solid var(--border-color); box-shadow: 0 10px 25px rgba(0,0,0,0.2); }
.exam-section h2 { margin-top: 0; border: none; color: #fff; display: flex; align-items: center; gap: 10px;}
.exam-section h2::before { content: "📝"; }
.exam-question { margin-bottom: 30px; background-color: rgba(0,0,0,0.2); padding: 20px; border-radius: 10px; }
.exam-question p { margin-bottom: 15px; color: #fff; font-weight: 600; }
.exam-options label { display: flex; align-items: center; margin-bottom: 10px; cursor: pointer; padding: 12px 15px; background: rgba(255,255,255,0.05); border-radius: 8px; transition: background 0.2s; border: 1px solid transparent;}
.exam-options label:hover { background: rgba(255,255,255,0.1); border-color: var(--border-color); }
.exam-options input { margin-right: 15px; width: 18px; height: 18px; accent-color: var(--accent-green); }
.btn-submit { background: linear-gradient(135deg, var(--accent-green), var(--accent-green-hover)); color: white; border: none; padding: 15px 30px; border-radius: 8px; font-weight: 700; cursor: pointer; font-size: 1.1em; transition: transform 0.2s, box-shadow 0.2s; width: 100%; letter-spacing: 0.5px; }
.btn-submit:hover:not(:disabled) { transform: translateY(-2px); box-shadow: 0 5px 15px rgba(16, 185, 129, 0.3); }
.btn-submit:disabled { opacity: 0.5; cursor: not-allowed; }
.exam-result { margin-top: 25px; padding: 20px; border-radius: 10px; display: none; font-weight: bold; text-align: center; font-size: 1.1rem; }

/* Mobile Responsiveness */
@media (max-width: 800px) {
    .hamburger { display: block; }
    .progress-container { display: none; }
    aside { position: fixed; left: -100%; z-index: 90; box-shadow: 5px 0 15px rgba(0,0,0,0.5); }
    aside.open { left: 0; }
    main { padding: 30px 20px; }
}

/* Python Playground */
#playground-panel {
    position: fixed;
    right: -450px;
    top: var(--header-height);
    width: 450px;
    height: calc(100vh - var(--header-height));
    background: var(--sidebar-bg);
    border-left: 1px solid var(--border-color);
    box-shadow: -5px 0 25px rgba(0,0,0,0.5);
    transition: right 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 150;
    display: flex;
    flex-direction: column;
}
#playground-panel.open { right: 0; }
.playground-header {
    padding: 15px 20px; background: var(--card-bg); border-bottom: 1px solid var(--border-color);
    display: flex; justify-content: space-between; align-items: center;
}
.playground-header h3 { margin: 0; color: var(--accent-green); font-size: 1.1rem; }
.playground-close { background: none; border: none; color: var(--text-muted); font-size: 1.5rem; cursor: pointer; transition: color 0.2s; }
.playground-close:hover { color: var(--accent-red); }
.playground-editor { flex: 1; display: flex; flex-direction: column; padding: 20px; }
#py-code {
    width: 100%; flex: 1; background: #0b0f19; color: #e2e8f0; border: 1px solid var(--border-color);
    border-radius: 8px; padding: 15px; font-family: 'Fira Code', monospace; font-size: 0.95rem;
    resize: none; margin-bottom: 15px; box-shadow: inset 0 2px 4px rgba(0,0,0,0.2);
}
#py-code:focus { outline: none; border-color: var(--accent-blue); }
#btn-run-py {
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-blue-hover)); color: #fff;
    border: none; padding: 12px; border-radius: 8px; cursor: pointer; font-weight: bold; font-size: 1rem;
    transition: transform 0.2s, box-shadow 0.2s; box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}
#btn-run-py:hover:not(:disabled) { transform: translateY(-2px); box-shadow: 0 6px 12px rgba(59, 130, 246, 0.3); }
#btn-run-py:disabled { opacity: 0.6; cursor: wait; }
.playground-output-container {
    flex: 0.8; padding: 20px; background: #0f172a; border-top: 1px solid var(--border-color); overflow-y: auto;
}
.playground-output-container h4 { margin: 0 0 10px 0; font-size: 0.9rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; }
#py-output { margin: 0; white-space: pre-wrap; font-family: 'Fira Code', monospace; font-size: 0.9rem; color: var(--accent-green); line-height: 1.4; }
.py-error { color: var(--accent-red) !important; }
@media (max-width: 800px) {
    #playground-panel { width: 100%; right: -100%; }
}