/* Main Stylesheet */
:root {
    --primary-color: #3498db;
    --secondary-color: #2c3e50;
    --success-color: #2ecc71;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --light-color: #ecf0f1;
    --dark-color: #34495e;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f8f9fa;
}

.sidebar {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    z-index: 100;
    padding: 48px 0 0;
    box-shadow: inset -1px 0 0 rgba(0, 0, 0, .1);
    background-color: var(--secondary-color);
}

.sidebar .nav-link {
    font-weight: 500;
    color: #ced4da; /* হালকা গাঢ় কালার */
    padding: 0.75rem 1rem;
    transition: color 0.3s ease;
}

.sidebar .nav-link.active {
    color: white;
    background-color: rgba(255, 255, 255, 0.1);
}

.sidebar .nav-link:hover {
    color: white;
}

.sidebar .nav-link:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.main-content {
    margin-left: 250px;
    padding: 20px;
}

.card {
    border: none;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    margin-bottom: 20px;
}

.card-header {
    background-color: white;
    border-bottom: 1px solid rgba(0, 0, 0, 0.125);
    font-weight: 600;
}

.table th {
    border-top: none;
    font-weight: 600;
}

.btn-primary {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

.btn-primary:hover {
    background-color: #2980b9;
    border-color: #2980b9;
}

.alert {
    border-radius: 8px;
}

/* Dashboard Stats */
.stat-card {
    border-left: 4px solid;
    transition: all 0.3s;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-card.sms {
    border-left-color: var(--primary-color);
}

.stat-card.voice {
    border-left-color: var(--success-color);
}

.stat-card.users {
    border-left-color: var(--warning-color);
}

.stat-card.groups {
    border-left-color: var(--danger-color);
}

/* Form Styles */
.form-control, .form-select {
    border-radius: 8px;
    padding: 10px 15px;
    transition: box-shadow 0.3s ease, border-color 0.3s ease;
}

.form-control:focus, .form-select:focus {
    box-shadow: 0 0 8px var(--primary-color);
    border-color: var(--primary-color);
    outline: none;
}

/* Responsive Adjustments */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
        padding: 10px 0; /* মোবাইলে একটু বেশি প্যাডিং */
    }
    .main-content {
        margin-left: 0;
    }
}