body { 
    background-color: #f0f2f5; margin: 0; padding: 20px; 
    display: flex; justify-content: center; align-items: center; min-height: 100vh;
    font-family: 'Helvetica Neue', Arial, sans-serif; transition: background-color 0.8s ease; 
}
body.dark-mode { background-color: #1a1a1a; }

.diag-card { 
    max-width: 480px; width: 100%; background: #fff; padding: 30px; 
    border-radius: 24px; box-shadow: 0 15px 35px rgba(0,0,0,0.1); transition: all 0.5s ease;
}
body.dark-mode .diag-card { 
    background: #2d2d2d; color: #fff; border: 2px solid #dc3545; 
    box-shadow: 0 0 20px rgba(220, 53, 69, 0.4); 
}

.title-main { text-align: center; color: #333; margin-bottom: 20px; font-size: 24px; }
body.dark-mode .title-main { color: #dc3545; text-shadow: 0 0 5px rgba(220,53,69,0.5); }

.progress-container { width: 100%; height: 8px; background: #eee; border-radius: 4px; margin-bottom: 20px; overflow: hidden; }
.progress-bar { height: 100%; width: 0%; background: #007bff; transition: 0.3s; }
body.dark-mode .progress-bar { background: #dc3545; }

.question-text { font-size: 19px; font-weight: bold; min-height: 80px; margin-bottom: 25px; line-height: 1.5; }

.button-group button { 
    display: block; width: 100%; padding: 16px; margin-bottom: 12px; 
    border-radius: 12px; border: 1px solid #ddd; background: #fff; 
    font-size: 16px; font-weight: bold; cursor: pointer; transition: 0.2s; 
}
body.dark-mode .button-group button { background: #3d3d3d; border-color: #555; color: #fff; }
body.dark-mode .button-group button:hover { background: #555; border-color: #dc3545; }

.btn-retry { 
    background: #495057 !important; color: #fff !important; border: none !important; 
    margin-top: 30px !important; padding: 25px !important; 
    font-size: 22px !important; font-weight: 900 !important;
    border-radius: 15px !important; cursor: pointer; width: 100%;
}
.btn-line { background: #06C755 !important; color: #fff !important; border: none !important; margin-top: 10px; width: 100%; padding: 15px; border-radius: 12px; font-weight: bold; cursor: pointer; }