:root {
            --glass-bg: rgba(255, 255, 255, 0.2);
            --glass-border: rgba(255, 255, 255, 0.3);
            --primary-text: #ffffff;
            --accent: #6366f1;
        }

        body {
            margin: 0;
            padding: 0;
            font-family: 'Plus Jakarta Sans', sans-serif;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            overflow: hidden; /* Supaya bola animasi tidak bikin scroll */
            background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
            position: relative;
        }

        /* Animasi Background (Bola-bola Aestetik) */
        .circle {
            position: absolute;
            border-radius: 50%;
            filter: blur(80px);
            z-index: 1;
        }

        .circle-1 {
            width: 300px;
            height: 300px;
            background: rgba(99, 102, 241, 0.4);
            top: -50px;
            left: 150px;
            animation: floating 5s infinite alternate ease-in-out;
        }

        .circle-2 {
            width: 400px;
            height: 400px;
            background: rgba(236, 72, 153, 0.3);
            bottom: -100px;
            right: 150px;
            animation: floating2 5s infinite alternate ease-in-out;
        }

        @keyframes floating {
            0% { transform: translateY(0); }
            100% { transform: translateY(200px); }
        }

        @keyframes floating2 {
            0% { transform: translateY(0); }
            100% { transform: translateY(-200px); }
        }

        /* Container Glassmorphism */
        .glass-card {
            position: relative;
            z-index: 10;
            background: var(--glass-bg);
            backdrop-filter: blur(15px); /* Efek Buram Kaca */
            -webkit-backdrop-filter: blur(15px);
            border: 1px solid var(--glass-border);
            border-radius: 24px;
            padding: 40px;
            width: 100%;
            max-width: 400px;
            box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
            color: var(--primary-text);
        }

        h1 {
            font-size: 22px;
            margin: 0 0 10px 0;
            text-align: center;
            font-weight: 700;
        }

        p.subtitle {
            text-align: center;
            font-size: 14px;
            opacity: 0.8;
            margin-bottom: 30px;
        }

        .input-group {
            margin-bottom: 20px;
        }

        label {
            display: block;
            font-size: 12px;
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-bottom: 8px;
            font-weight: 600;
        }

        input {
            width: 100%;
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid var(--glass-border);
            border-radius: 12px;
            padding: 12px 15px;
            color: white;
            font-size: 16px;
            box-sizing: border-box;
            outline: none;
            transition: 0.3s;
        }

        input:focus {
            background: rgba(255, 255, 255, 0.15);
            border-color: var(--accent);
            box-shadow: 0 0 15px rgba(99, 102, 241, 0.3);
        }

        button {
            width: 100%;
            padding: 14px;
            background: var(--accent);
            color: white;
            border: none;
            border-radius: 12px;
            font-weight: 700;
            cursor: pointer;
            margin-top: 10px;
            transition: 0.3s;
            box-shadow: 0 10px 15px -3px rgba(99, 102, 241, 0.4);
        }

        button:hover {
            transform: translateY(-2px);
            background: #4f46e5;
        }

        /* Tombol Group */
        .button-group { display: flex; gap: 10px; margin-top: 20px; }

        #btn-cek {
            flex: 3;
            padding: 14px;
            background: var(--accent);
            color: white;
            border: none;
            border-radius: 12px;
            font-weight: 700;
            cursor: pointer;
            box-shadow: 0 10px 15px -3px rgba(99, 102, 241, 0.4);
        }

        #btn-reset {
            flex: 1;
            background: var(--glass-bg);
            border: 1px solid var(--glass-border);
            border-radius: 12px;
            cursor: pointer;
            color: var(--primary-text);
            transition: 0.5s;
        }

        #btn-reset:hover { transform: rotate(180deg); }

        /* Area Hasil */
        #result-box {
            margin-top: 30px;
            padding: 20px;
            background: rgba(0, 0, 0, 0.2);
            border-radius: 16px;
            border: 2px dashed #e1e4e8;
            text-align: center;
            transition: all 0.5s ease;
        }

        .npm-title {
            font-size: 11px; 
            opacity: 0.6; 
            letter-spacing: 1px; 
            margin-bottom: 2px;
        }

        .npm-output {
            font-size: 16px; 
            font-weight: 600; 
            margin-bottom: 15px; 
            letter-spacing: 2px;
        }

        .huruf-mutu-title {
            font-size: 11px; 
            opacity: 0.6; 
            letter-spacing: 1px;
        }

        .grade-text {
            font-size: 48px;
            font-weight: 800;
            margin: 5px 0;
            background: linear-gradient(to bottom, var(--primary-text), var(--glass-border));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }