:root {
        --mesh-1: #818cf8; 
        --mesh-2: #c084fc; 
        --mesh-3: #4fd1c5; 
        --mesh-4: #60a5fa; 
        --btn-grad: linear-gradient(135deg, #818cf8, #c084fc);
        --btn-mesh: linear-gradient(-45deg, var(--mesh-1), var(--mesh-2), var(--mesh-3), var(--mesh-4));
    }

    * { margin: 0; padding: 0; box-sizing: border-box; font-family: Poppins, sans-serif; }

    body {
        height: 100vh;
        display: flex;
        justify-content: center;
        align-items: center;
        background: #f1f5f9;
        overflow: hidden;
    }

    canvas { position: absolute; top: 0; left: 0; z-index: 0; opacity: 0.5; }

    .container {
        width: 1000px;
        height: 600px;
        border-radius: 40px;
        overflow: hidden;
        background: #ffffff;
        box-shadow: 0 40px 100px -20px rgba(0, 0, 0, 0.08);
        position: relative;
        z-index: 1;
    }

    /* THE ANIMATED PANEL BACKGROUND */
    .overlay {
        position: absolute;
        top: 0;
        left: 50%;
        width: 50%;
        height: 100%;
        background: linear-gradient(-45deg, var(--mesh-1), var(--mesh-2), var(--mesh-3), var(--mesh-4));
        background-size: 300% 300%;
        animation: meshFlow 15s ease infinite;
        border-radius: 120px 0 0 0;
        transition: transform 0.8s cubic-bezier(0.65, 0, 0.35, 1), 
                    border-radius 0.8s cubic-bezier(0.65, 0, 0.35, 1);
        z-index: 2;
        overflow: hidden;
    }

    /* GEOMETRIC GRID EFFECT */
    .overlay::before {
        content: "";
        position: absolute;
        top: 0; left: 0; width: 100%; height: 100%;
        background-image: radial-gradient(rgba(255,255,255,0.2) 1px, transparent 1px);
        background-size: 30px 30px;
        z-index: 1;
        opacity: 0.5;
    }

    /* FLOATING GEOMETRY SHAPES */
    .geo-shape {
        position: absolute;
        background: rgba(255, 255, 255, 0.1);
        border: 1px solid rgba(255, 255, 255, 0.2);
        z-index: 0;
        animation: floatShape 20s linear infinite;
    }

    .shape-1 { width: 80px; height: 80px; border-radius: 20px; top: 10%; left: 10%; }
    .shape-2 { width: 120px; height: 120px; border-radius: 50%; bottom: 10%; right: 10%; animation-duration: 25s; }
    .shape-3 { 
        width: 0; height: 0; 
        border-left: 50px solid transparent; border-right: 50px solid transparent;
        border-bottom: 80px solid rgba(255,255,255,0.08);
        background: transparent; border-radius: 0; border-top: none;
        top: 40%; left: 60%; animation-duration: 30s;
    }

    @keyframes floatShape {
        0% { transform: translate(0, 0) rotate(0deg); }
        50% { transform: translate(20px, 40px) rotate(180deg); }
        100% { transform: translate(0, 0) rotate(360deg); }
    }

    .container.active .overlay {
        transform: translateX(-100%);
        border-radius: 0 120px 120px 0;
    }

    @keyframes meshFlow {
        0% { background-position: 0% 50%; }
        50% { background-position: 100% 50%; }
        100% { background-position: 0% 50%; }
    }

    .panel {
        position: absolute;
        width: 50%;
        height: 100%;
        right: 0;
        padding: 60px;
        color: #fff;
        z-index: 3;
        display: flex;
        flex-direction: column;
        justify-content: center;
        transition: transform 0.8s cubic-bezier(0.65, 0, 0.35, 1);
    }

    .container.active .panel { transform: translateX(-100%); }

    .panel h1 { font-size: 38px; font-weight: 600; margin-bottom: 15px; position: relative; z-index: 10; }
    .panel p { font-size: 15px; opacity: 0.9; line-height: 1.7; margin-bottom: 30px; font-weight: 300; position: relative; z-index: 10; }

    .panel button {
        padding: 12px 30px;
        border: 1px solid rgba(255, 255, 255, 0.4);
        border-radius: 15px;
        background: rgba(255, 255, 255, 0.1);
        backdrop-filter: blur(5px);
        color: #fff;
        cursor: pointer;
        font-weight: 500;
        transition: 0.3s ease;
        text-transform: uppercase;
        font-size: 11px;
        letter-spacing: 1.5px;
        width: fit-content;
        position: relative; z-index: 10;
    }

    .panel button:hover { background: #fff; color: var(--mesh-1); }

    /* BUTTONS & SEPARATOR */
    .btn {
        width: 100%; padding: 12px; border: none; border-radius: 15px;
        background: var(--btn-mesh);
        color: #fff;
        font-weight: 600; font-size: 15px; transition: 0.4s;
        background-size: 300% 300%;
        animation: meshFlow 15s ease infinite;
        cursor: pointer;
        display: flex;
        justify-content: center;
        align-items: center;
    }

    .btn:hover { transform: translateY(-3px); 
    box-shadow: 0 15px 30px -5px rgba(129, 140, 248, 0.5); filter: brightness(1.1); }

    .btn:active {
    transform: translateY(-1px);
    }

    /* LOADING SPINNER */
    .spinner {
        display: none;
        width: 18px;
        height: 18px;
        border: 2px solid rgba(255,255,255,0.3);
        border-radius: 50%;
        border-top-color: #fff;
        animation: spin 0.8s linear infinite;
        margin-left: 10px;
    }
    @keyframes spin { to { transform: rotate(360deg); } }
    .btn.loading .spinner { display: block; }
    .btn.loading { pointer-events: none; opacity: 0.8; }

    .separator {
        display: flex; align-items: center; text-align: center; margin: 20px 0;
        color: #94a3b8; font-size: 13px; font-weight: 500;
    }
    .separator::before, .separator::after { content: ''; flex: 1; border-bottom: 1px solid #e2e8f0; }
    .separator:not(:empty)::before { margin-right: 15px; }
    .separator:not(:empty)::after { margin-left: 15px; }

    .google-btn {
        background: #f8fafc; color: #475569; border: 1px solid #e2e8f0;
        width: 100%; padding: 12px; border-radius: 15px; display: flex;
        align-items: center; justify-content: center; gap: 12px;
        cursor: pointer; font-weight: 600; transition: 0.3s;
    }
    .google-btn:hover { background: #f1f5f9; }

    /* FORM STYLING */
    .form-container {
        position: absolute; width: 50%; height: 100%; left: 0;
        transition: 0.8s cubic-bezier(0.65, 0, 0.35, 1); z-index: 4;
    }
    .container.active .form-container { transform: translateX(100%); }

    .form {
        position: absolute; width: 100%; height: 100%; padding: 70px;
        display: flex; flex-direction: column; justify-content: center;
        transition: opacity 0.4s ease;
    }

    .input-box { margin-bottom: 20px; position: relative; }
    .input-box input {
        width: 100%; padding: 12px; border-radius: 15px; border: 1px solid #e2e8f0;
        outline: none; background: #f8fafc; font-size: 14px;
    }
    .input-box input:focus { border-color: var(--mesh-1); background: #fff; }
    .input-box label { position: absolute; left: 16px; top: 10px; color: #94a3b8; transition: 0.3s; pointer-events: none; }
    .input-box input:focus + label, .input-box input:valid + label { top: -10px; left: 12px; font-size: 12px; background: #fff; padding: 0 8px; color: var(--mesh-1); }

    .sign-up { opacity: 0; pointer-events: none; }
    .container.active .sign-in { opacity: 0; pointer-events: none; }
    .container.active .sign-up { opacity: 1; pointer-events: all; }

    /* TOAST NOTIFICATION STYLES */
    .toast-container {
        position: fixed;
        top: 20px;
        right: 20px;
        z-index: 9999;
    }

    .toast {
        background: #fff;
        color: #333;
        padding: 16px 25px;
        border-radius: 12px;
        box-shadow: 0 10px 30px rgba(0,0,0,0.1);
        display: flex;
        align-items: center;
        gap: 12px;
        margin-bottom: 10px;
        transform: translateX(120%);
        transition: transform 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
        border-left: 5px solid #818cf8;
    }

    .toast.show {
        transform: translateX(0);
    }

    .toast i {
        font-size: 20px;
    }

    /* Toast Variants */
    .toast-success { border-left-color: #10b981; }
    .toast-success i { color: #10b981; }

    .toast-error { border-left-color: #ef4444; }
    .toast-error i { color: #ef4444; }

    .toast-warning { border-left-color: #f59e0b; }
    .toast-warning i { color: #f59e0b; }

    .toast span {
        font-size: 14px;
        font-weight: 500;
        color: #475569;
    }