:root {
    --bg-color: #0d0d12;
    --box-bg: rgba(26, 26, 36, 0.85);
    --border-color: rgba(255, 0, 255, 0.3);
    
    --neon-pink: #ff00ff;
    --neon-blue: #00f0ff;
    --neon-green: #00ffcc;
    --neon-red: #ff3333;
    
    --text-main: #e0e0e0;
    --text-muted: #8892b0;
    
    --font-sans: 'Outfit', sans-serif;
    --font-mono: 'Fira Code', monospace;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: var(--font-sans);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
    background-image: 
        radial-gradient(circle at 15% 50%, rgba(255, 0, 255, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 85% 30%, rgba(0, 240, 255, 0.08) 0%, transparent 50%);
}

#particles-bg {
    position: fixed;
    top: 0; left: 0; width: 100%; height: 100%;
    z-index: -1;
    opacity: 0.5;
    background-image: linear-gradient(var(--border-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--border-color) 1px, transparent 1px);
    background-size: 40px 40px;
    background-position: center center;
    mask-image: radial-gradient(circle at center, black 30%, transparent 80%);
    -webkit-mask-image: radial-gradient(circle at center, black 30%, transparent 80%);
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* --- HEADER & HUD --- */
header {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.logo-box {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

h1 {
    font-family: var(--font-mono);
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--neon-pink);
    text-transform: uppercase;
    letter-spacing: 2px;
    text-shadow: 0 0 10px rgba(255, 0, 255, 0.5);
}

.hud {
    display: flex;
    gap: 1.5rem;
    background: var(--box-bg);
    padding: 0.75rem 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    backdrop-filter: blur(10px);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5), inset 0 0 10px rgba(0, 240, 255, 0.1);
}

.stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-label {
    font-size: 0.7rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
    letter-spacing: 1px;
}

.stat-value {
    font-size: 1.25rem;
    font-weight: 800;
    font-family: var(--font-mono);
}

.text-glow { color: var(--neon-blue); text-shadow: 0 0 8px rgba(0, 240, 255, 0.6); }
.highlight { color: var(--neon-green); text-shadow: 0 0 8px rgba(0, 255, 204, 0.6); }

/* --- MAIN CONTENT PANELS --- */
main {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    animation: fadeIn 0.5s ease-out;
}

.panel {
    background: var(--box-bg);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: 12px;
    padding: 2.5rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
    animation: slideUp 0.4s ease-out forwards;
}

.panel::before {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 4px;
    background: linear-gradient(90deg, var(--neon-pink), var(--neon-blue), var(--neon-green));
}

.theory-content h2 {
    color: var(--neon-blue);
    font-size: 2rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px dashed rgba(0, 240, 255, 0.3);
    padding-bottom: 0.5rem;
}

.theory-content h3 {
    color: var(--neon-green);
    margin: 1.5rem 0 1rem;
}

.theory-content p, .theory-content li {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: #ccc;
}

.theory-content ul {
    margin-left: 1.5rem;
    margin-bottom: 1.5rem;
}

.theory-content strong {
    color: #fff;
}

code {
    font-family: var(--font-mono);
    background: rgba(0, 0, 0, 0.5);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    color: var(--neon-pink);
    font-size: 0.9em;
    border: 1px solid rgba(255, 0, 255, 0.2);
}

/* --- INTERACTIVE BLOCK --- */
.interactive-box {
    margin-top: 2rem;
    background: rgba(0, 0, 0, 0.3);
    border: 1px dashed var(--neon-blue);
    border-radius: 8px;
    padding: 2rem;
    position: relative;
}

.interactive-box h3 {
    color: var(--text-main);
    font-size: 1.3rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.options-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.option {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 6px;
    padding: 1rem 1.5rem;
    cursor: pointer;
    font-family: var(--font-mono);
    color: var(--text-muted);
    transition: all 0.2s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    position: relative;
    overflow: hidden;
}

.option:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.3);
    color: #fff;
    transform: translateX(5px);
}

.option.selected {
    background: rgba(0, 240, 255, 0.1);
    border-color: var(--neon-blue);
    color: #fff;
    box-shadow: inset 0 0 15px rgba(0, 240, 255, 0.2);
}

.option.selected::before {
    content: '';
    position: absolute;
    left: 0; top: 0;
    height: 100%; width: 4px;
    background-color: var(--neon-blue);
    box-shadow: 0 0 10px var(--neon-blue);
}

/* Result styles for options */
.option.correct {
    background: rgba(0, 255, 204, 0.15);
    border-color: var(--neon-green);
    color: var(--neon-green);
}

.option.incorrect {
    background: rgba(255, 51, 51, 0.15);
    border-color: var(--neon-red);
    color: var(--neon-red);
    opacity: 0.6;
}

/* --- BUTTONS --- */
.action-btn {
    display: inline-block;
    background: transparent;
    color: var(--neon-pink);
    border: 2px solid var(--neon-pink);
    border-radius: 4px;
    padding: 0.8rem 2rem;
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 1rem;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-top: 2rem;
    transition: all 0.3s ease;
    width: 100%;
    position: relative;
    overflow: hidden;
}

.action-btn::before {
    content: '';
    position: absolute;
    top: 50%; left: 50%;
    width: 300%; height: 300%;
    background: var(--neon-pink);
    border-radius: 50%;
    transform: translate(-50%, -50%) scale(0);
    transition: transform 0.5s ease;
    z-index: -1;
}

.action-btn:hover {
    color: var(--bg-color);
    box-shadow: 0 0 20px rgba(255, 0, 255, 0.6);
}

.action-btn:hover::before {
    transform: translate(-50%, -50%) scale(1);
}

.action-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    border-color: #555;
    color: #555;
    box-shadow: none;
}
.action-btn:disabled::before { display: none; }

.btn-primary { background: rgba(255, 0, 255, 0.1); }
.btn-success {
    border-color: var(--neon-green);
    color: var(--neon-green);
}
.btn-success::before { background: var(--neon-green); }
.btn-success:hover { box-shadow: 0 0 20px rgba(0, 255, 204, 0.6); }

.feedback-msg {
    margin-top: 1.5rem;
    font-weight: 700;
    text-align: center;
    font-size: 1.1rem;
    min-height: 1.5em; /* reserve space */
    animation: fadeIn 0.3s ease;
}

.text-success { color: var(--neon-green); text-shadow: 0 0 5px rgba(0,255,204,0.5); }
.text-error { color: var(--neon-red); text-shadow: 0 0 5px rgba(255,51,51,0.5); }
.text-warning { color: gold; }

/* Final Exam Styles */
.exam-header {
    text-align: center;
    margin-bottom: 2rem;
}

.exam-header h2 {
    color: var(--neon-red);
    font-size: 2.5rem;
    text-transform: uppercase;
    letter-spacing: 4px;
    text-shadow: 0 0 15px rgba(255,51,51,0.6);
    animation: pulseRed 2s infinite;
}

.progress-bar-container {
    width: 100%;
    height: 10px;
    background: rgba(255,255,255,0.1);
    border-radius: 5px;
    margin: 1rem 0 2rem;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--neon-purple), var(--neon-pink));
    width: 0%;
    transition: width 0.3s ease;
}

/* Result Screens */
.result-screen {
    text-align: center;
    padding: 3rem 1rem;
}

.result-screen h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.score-circle {
    width: 150px;
    height: 150px;
    border-radius: 50%;
    border: 4px solid var(--neon-green);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    font-weight: 800;
    margin: 2rem auto;
    font-family: var(--font-mono);
    color: #fff;
    box-shadow: 0 0 30px rgba(0,255,204,0.4), inset 0 0 20px rgba(0,255,204,0.2);
}

.score-circle.failed {
    border-color: var(--neon-red);
    box-shadow: 0 0 30px rgba(255,51,51,0.4), inset 0 0 20px rgba(255,51,51,0.2);
}

/* Animations */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideUp { 
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}
@keyframes pulseRed {
    0% { text-shadow: 0 0 10px rgba(255,51,51,0.4); }
    50% { text-shadow: 0 0 20px rgba(255,51,51,0.8), 0 0 30px red; }
    100% { text-shadow: 0 0 10px rgba(255,51,51,0.4); }
}

.spinner {
    width: 40px; height: 40px;
    border: 4px solid rgba(255,0,255,0.2);
    border-top-color: var(--neon-pink);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 2rem auto;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* Mobile */
@media (max-width: 600px) {
    .container { padding: 1rem; }
    .panel { padding: 1.5rem; }
    .hud { flex-direction: row; font-size: 0.9em; gap: 1rem; }
    h1 { font-size: 1.4rem; }
    .action-btn { font-size: 0.9rem; padding: 0.7rem 1rem; }
}