body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: #f0f2f5;
    margin: 0;
    padding: 0;
}
.app-container {
    max-width: 1200px;
    margin: 40px auto;
    padding: 20px;
    background-color: #ffffff;
    border-radius: 15px;
}
.header-text {
    text-align: center;
    color: #2c3e50;
    font-size: 2.2em;
    margin-bottom: 30px;
    border-bottom: 2px solid #ffc107;
    padding-bottom: 10px;
}
.main-container {
    display: flex;
    flex-direction: column;
    gap: 40px;
}
.category-section {
    padding: 20px;
    background-color: #f8f9fa;
    border-radius: 10px;
    border: 1px solid #e9ecef;
}
.category-header {
    color: #34495e;
    font-size: 1.5em;
    margin-bottom: 20px;
    border-left: 5px solid #3498db;
    padding-left: 10px;
    text-transform: uppercase;
    letter-spacing: 1px;
}
.exercise-grid-style {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
}
.exercise-card-style:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
    background-color: #e8f5ff;
}
.modal-content {
    border-radius: 15px;
    border: none;
    background-color: #ffffff;
}
.start-chat-button-style {
    background-color: #ffc107;
    border: none;
    font-weight: 500;
    color: white !important;
    padding: 12px 24px;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(255,193,7,0.2);
    transition: background-color 0.3s ease, transform 0.2s ease;
    letter-spacing: 0.5px;
}
.start-chat-button-style:hover {
    background-color: #e0a800;
    transform: translateY(-2px);
}

.exercise-button-style:hover {
    transform: translateY(-2px);
}