:root {
    --primary-color: #FF9900; /* AWS Orange */
    --secondary-color: #232F3E; /* AWS Dark Blue */
    --text-color: #ffffff;
    --bg-gradient: linear-gradient(135deg, #232F3E 0%, #1a232e 100%);
    --card-bg: rgba(255, 255, 255, 0.1);
    --glass-border: 1px solid rgba(255, 255, 255, 0.2);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

body {
    background: var(--bg-gradient);
    color: var(--text-color);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
}

.app-container {
    width: 100%;
    max-width: 600px;
    padding: 20px;
}

/* Header */
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.score-badge {
    background: rgba(255, 153, 0, 0.2);
    padding: 5px 15px;
    border-radius: 20px;
    border: 1px solid var(--primary-color);
    font-weight: bold;
}

/* Glass Card */
.quiz-card {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: var(--glass-border);
    border-radius: 16px;
    padding: 2rem;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
    min-height: 400px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

h2 {
    font-size: 1.4rem;
    margin-bottom: 1.5rem;
    line-height: 1.4;
}

.progress-bar {
    width: 100%;
    height: 6px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 3px;
    margin-bottom: 1.5rem;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--primary-color);
    width: 0%;
    transition: width 0.3s ease;
}

.options-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

button.option-btn {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: 15px;
    border-radius: 8px;
    color: white;
    text-align: left;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
}

button.option-btn:hover {
    background: rgba(255, 153, 0, 0.2);
    border-color: var(--primary-color);
}

button.correct {
    background: rgba(46, 204, 113, 0.3) !important;
    border-color: #2ecc71 !important;
}

button.wrong {
    background: rgba(231, 76, 60, 0.3) !important;
    border-color: #e74c3c !important;
}

.hidden { display: none !important; }

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid rgba(255, 255, 255, 0.1);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 20px;
}

@keyframes spin { 0% { transform: rotate(0deg); } 100% { transform: rotate(360deg); } }

.loader-container { text-align: center; }

#end-screen { text-align: center; }
.trophy-icon { font-size: 4rem; color: #f1c40f; margin-bottom: 20px; }
.restart-btn {
    margin-top: 20px;
    padding: 12px 30px;
    background: var(--primary-color);
    border: none;
    border-radius: 25px;
    color: black;
    font-weight: bold;
    cursor: pointer;
    font-size: 1rem;
}

footer {
    text-align: center;
    margin-top: 20px;
    font-size: 0.8rem;
    opacity: 0.6;
}