:root {
            --bg: #0f1222;
            --bg-accent: radial-gradient(1200px 600px at 10% 10%, #3f51b54d, transparent 40%),
                radial-gradient(1200px 600px at 90% 90%, #8e24aa33, transparent 40%),
                linear-gradient(180deg, #0f1222, #0c0f1b);
            --panel: rgba(255, 255, 255, 0.06);
            --panel-2: rgba(255, 255, 255, 0.08);
            --text: #e9ecf1;
            --muted: #a7b0c3;
            --accent: #6ee7ff;
            --accent-2: #9a6dff;
            --btn: #171a2b;
            --btn-hover: #1d2034;
            --op: #2a2e47;
            --danger: #ff5a6e;
            --success: #22d3a8;
            --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
            --glass: saturate(160%) blur(8px);
        }

        [data-theme="light"] {
            --bg: #eef1f7;
            --bg-accent: radial-gradient(1200px 600px at 15% 10%, #9cc1ff3b, transparent 45%),
                radial-gradient(1200px 600px at 85% 90%, #caa6ff38, transparent 40%),
                linear-gradient(180deg, #eef1f7, #e7ebf3);
            --panel: rgba(255, 255, 255, 0.75);
            --panel-2: rgba(255, 255, 255, 0.9);
            --text: #161a2b;
            --muted: #5a6478;
            --accent: #2d8cff;
            --accent-2: #7a3cff;
            --btn: #ffffff;
            --btn-hover: #f4f6fb;
            --op: #edf1fb;
            --danger: #ff3860;
            --success: #00c48c;
            --shadow: 0 10px 25px rgba(0, 0, 0, 0.08);
            --glass: saturate(140%) blur(6px);
        }

        * {
            box-sizing: border-box;
        }

        html,
        body {
            height: 100%;
            margin: 0;
            font-family: ui-sans-serif, -apple-system, Segoe UI, Roboto, Ubuntu, Cantarell, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji", "Segoe UI Emoji";
            color: var(--text);
            background: var(--bg-accent), var(--bg);
        }

        .wrap {
            min-height: 100%;
            display: grid;
            place-items: center;
            padding: 24px;
        }

        .calc {
            width: min(450px, 92vw);
            background: var(--panel);
            border: 1px solid rgba(255, 255, 255, 0.08);
            border-radius: 18px;
            box-shadow: var(--shadow);
            overflow: clip;
            backdrop-filter: var(--glass);
        }

        .topbar {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 14px 16px;
            background: linear-gradient(180deg, var(--panel-2), transparent);
            border-bottom: 1px solid rgba(255, 255, 255, 0.08);
        }

        .title {
            font-weight: 700;
            letter-spacing: .4px;
        }

        .subtitle {
            font-size: 12px;
            color: var(--muted);
        }

        .theme-toggle {
            display: inline-flex;
            align-items: center;
            gap: 8px;
            background: linear-gradient(135deg, var(--op), transparent);
            border: 1px solid rgba(255, 255, 255, 0.08);
            color: var(--text);
            padding: 8px 12px;
            border-radius: 12px;
            cursor: pointer;
            user-select: none;
            transition: transform .15s ease, background .2s ease;
        }

        .theme-toggle:hover {
            transform: translateY(-1px);
        }

        .theme-toggle .dot {
            width: 18px;
            height: 18px;
            border-radius: 50%;
            background: linear-gradient(135deg, var(--accent), var(--accent-2));
            box-shadow: 0 0 12px color-mix(in srgb, var(--accent) 50%, transparent);
        }

        .display {
            padding: 18px 20px 10px;
            min-height: 108px;
            display: flex;
            flex-direction: column;
            align-items: flex-end;
            justify-content: center;
            gap: 8px;
        }

        .mini {
            min-height: 20px;
            color: var(--muted);
            font-size: 14px;
            letter-spacing: .4px;
        }

        .main {
            width: 100%;
            text-align: right;
            font-size: clamp(28px, 6.2vw, 42px);
            font-weight: 800;
            letter-spacing: .6px;
            word-break: break-all;
        }

        .keys {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 10px;
            padding: 16px;
            background: linear-gradient(180deg, transparent, rgba(255, 255, 255, 0.03));
        }

        .btn {
            appearance: none;
            border: none;
            padding: 16px 14px;
            font-size: 18px;
            font-weight: 700;
            color: var(--text);
            background: var(--btn);
            border-radius: 14px;
            cursor: pointer;
            transition: transform .06s ease, background .15s ease, box-shadow .15s ease, opacity .2s ease;
            box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.05);
            user-select: none;
        }

        .btn:hover {
            background: var(--btn-hover);
        }

        .btn:active,
        .btn.active {
            transform: translateY(1px);
            box-shadow: inset 0 0 0 999px rgba(0, 0, 0, 0.06);
        }

        .btn.op {
            background: linear-gradient(180deg, var(--op), color-mix(in srgb, var(--op) 85%, var(--accent) 15%));
            border: 1px solid rgba(255, 255, 255, 0.06);
        }

        .btn.op.active-op {
            outline: 0;
            background: linear-gradient(180deg, color-mix(in srgb, var(--op) 50%, var(--accent) 50%), var(--op));
            box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent) 45%, transparent);
        }

        .btn.equals {
            background: linear-gradient(135deg, var(--accent), var(--accent-2));
            color: #0b0f1a;
            box-shadow: 0 4px 16px color-mix(in srgb, var(--accent) 30%, transparent);
        }

        .btn.equals:hover {
            opacity: .95;
        }

        .btn.danger {
            color: #fff;
            background: linear-gradient(180deg, color-mix(in srgb, var(--danger) 30%, #111 70%), #2a1121);
        }

        .btn.zero {
            grid-column: span 2;
        }

        .footer {
            padding: 6px 16px 14px;
            display: flex;
            justify-content: space-between;
            align-items: center;
            color: var(--muted);
            font-size: 12px;
        }
        .label{
            padding: 6px 16px 14px;
            font-size: 12px;
            color: var(--muted);
        }
        .kbd {
            font: inherit;
            font-weight: 700;
            font-size: 12px;
            background: rgba(255, 255, 255, 0.08);
            border: 1px solid rgba(255, 255, 255, 0.18);
            padding: 2px 6px;
            border-radius: 6px;
        }

        .toast {
            position: fixed;
            left: 50%;
            bottom: 22px;
            transform: translateX(-50%) translateY(20px);
            background: var(--panel-2);
            color: var(--text);
            border: 1px solid rgba(255, 255, 255, 0.12);
            padding: 10px 14px;
            border-radius: 10px;
            box-shadow: var(--shadow);
            opacity: 0;
            pointer-events: none;
            transition: opacity .25s ease, transform .25s ease;
        }

        .toast.show {
            opacity: 1;
            transform: translateX(-50%) translateY(0);
        }

        @media (max-width: 420px) {
            .btn {
                padding: 14px 12px;
                font-size: 17px;
            }

            .topbar {
                padding: 12px 14px;
            }

            .keys {
                gap: 8px;
                padding: 14px;
            }

            .footer {
                padding: 6px 14px 12px;
            }
        }