.popup-backdrop {
            position: fixed;
            inset: 0;
            background: rgba(0, 0, 0, 0.78);
            z-index: 999;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: opacity .3s;
        }

        .popup-backdrop[hidden] {
            display: none;
        }

        .popup.login-signup-popup {
                position: fixed;
                font-family: 'Inter', system-ui, sans-serif;
                z-index: 1000;
                top: 0;
                left: 0;
                width: 100%;
                height: 100vh;
                justify-content: center;
                /* display: flex; */
                align-items: center;
                /* background-color: black; */
            
        }

        .popup-content {
            background: transparent;
            border: none;
            box-shadow: none;
            min-width: 340px;
            max-width: 370px;
            perspective: 1400px;
            border-radius: 14px;
            position: relative;
            z-index: 1001;
            background: black;
        }

        .flip-card-inner {
            position: relative;
            width: 100%;
            min-height: 430px;
            transition: transform 0.7s cubic-bezier(.68, -0.55, .27, 1.55);
            transform-style: preserve-3d;
        }

        .flip-card-inner.flipped {
            transform: rotateY(180deg);
        }

        .card-face {
            position: absolute;
            width: 100%;
            height: 100%;
            backface-visibility: hidden;
            background: var(--card-bg);
            border-radius: 14px;
            box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.35);
            color: var(--text-color);
            padding: 36px 28px 28px 28px;
            display: flex;
            flex-direction: column;
            justify-content: center;
            gap: 18px;
        }

        .card-face.signup {
            transform: rotateY(180deg);
        }

        .close-btn {
            position: absolute;
            top: 14px;
            right: 22px;
            font-size: 1.6rem;
            color: var(--accent);
            cursor: pointer;
            z-index: 2;
            transition: color .2s;
        }

        .close-btn:hover {
            color: #fff;
        }

        .card-face h2 {
            color: var(--accent);
            font-size: 2rem;
            margin: 0 0 10px 0;
            font-weight: 700;
            letter-spacing: 1px;
            text-align: center;
        }

        .auth-form {
            display: flex;
            flex-direction: column;
            gap: 18px;
        }

        .input-group {
            position: relative;
            display: flex;
            align-items: center;
        }

        .auth-input {
            width: 100%;
            padding: 12px 40px 12px 16px;
            background: var(--input-bg);
            border: 1.5px solid var(--input-border);
            border-radius: 7px;
            color: var(--text-color);
            font-size: 1rem;
            outline: none;
            transition: border .2s, background .2s;
            box-shadow: 0 2px 6px 0 rgba(0, 0, 0, 0.10);
        }

        .auth-input:focus {
            border-color: var(--accent);
            background: var(--input-hover);
        }

        .input-icon {
            position: absolute;
            right: 12px;
            font-size: 1.3rem;
            color: #aaa;
            cursor: pointer;
            transition: color .2s;
        }

        .input-icon:hover {
            color: var(--accent);
        }

        .switch-link {
            color: var(--accent);
            text-underline-offset: 2px;
            cursor: pointer;
            font-weight: 600;
        }

        .switch-link:hover {
            text-decoration: underline;
        }

        @media (max-width: 400px) {
            .popup-content {
                min-width: 96vw;
            }

            .card-face {
                padding: 16px 7vw 18px 7vw;
            }
        }