:root {
    --primary-color: #0d6efd;
    --secondary-color: #6c757d;
    --success-color: #198754;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --info-color: #0dcaf0;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

main {
    flex: 1;
}

.footer {
    margin-top: auto;
}

.card {
    border-radius: 8px;
    margin-bottom: 1.5rem;
}

.card-header {
    background-color: #f8f9fa;
    border-bottom: 2px solid #dee2e6;
}

.navbar-brand {
    font-weight: 600;
    font-size: 1.5rem;
}

.table th {
    background-color: #f8f9fa;
    font-weight: 600;
}

.badge {
    padding: 0.5em 0.75em;
}

/* Timer Display */
#timer-duration {
    font-family: 'Courier New', monospace;
    font-size: 1.2em;
    font-weight: bold;
}

#active-timer-display {
    border-left: 5px solid var(--success-color);
}

/* Progress bars */
.progress {
    border-radius: 4px;
}

.progress-bar {
    transition: width 0.6s ease;
}

/* Forms */
.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.2rem rgba(13, 110, 253, 0.25);
}

/* Buttons */
.btn {
    border-radius: 6px;
    padding: 0.5rem 1rem;
    font-weight: 500;
}

.btn-sm {
    padding: 0.25rem 0.5rem;
}

/* Cards hover effect */
.card:hover {
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    transition: box-shadow 0.3s ease;
}

/* Table hover effect */
.table-hover tbody tr:hover {
    background-color: rgba(0,0,0,0.025);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .navbar-brand {
        font-size: 1.2rem;
    }
    
    .card {
        margin-bottom: 1rem;
    }
    
    h1 {
        font-size: 1.75rem;
    }
}

/* List group items */
.list-group-item {
    border-left: 3px solid transparent;
    transition: border-left-color 0.3s ease;
}

.list-group-item:hover {
    border-left-color: var(--primary-color);
    background-color: #f8f9fa;
}

/* Alert customization */
.alert {
    border-left: 4px solid;
}

.alert-success {
    border-left-color: var(--success-color);
}

.alert-danger {
    border-left-color: var(--danger-color);
}

.alert-warning {
    border-left-color: var(--warning-color);
}

.alert-info {
    border-left-color: var(--info-color);
}