/* 2. Main Content Area */
        .main-content {
            margin-left: 250px; /* Offset to clear sidebar */
            padding: 20px 30px;
            width: calc(100% - 250px);
        }

        /* 3. KPI Cards Layout (Enhanced) */
        .kpi-row {
            margin-bottom: 30px;
        }
        .kpi-card {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 20px;
            background-color: #ffffff;
            border-radius: 4px; /* Soft corners */
            box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24); /* Subtle Material shadow */
            transition: all 0.3s cubic-bezier(.25,.8,.25,1);
        }
        .kpi-card:hover {
             box-shadow: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
        }
        .kpi-card .kpi-icon {
            font-size: 40px;
            margin-right: 15px;
            color: #3f51b5; /* Primary color for icons */
        }
        .kpi-card .kpi-value h5 {
            margin: 0;
            font-weight: 500;
            font-size: 1.8rem;
            line-height: 1.2;
        }
        .kpi-card .kpi-value p {
            margin: 0;
            color: #757575;
            font-size: 0.9rem;
        }
        
        /* 4. STS Listing & Packages Card */
        .data-card {
            min-height: 300px; /* Ensure visual balance */
        }