@import url('https://fonts.googleapis.com/css?family=Raleway:400,700');

    /* --- Structure globale --- */
    .container-animation {
        position: relative;
        width: 100%;
        height: 100vh;
        overflow: hidden;
        background: #fff;
        font-family: 'Raleway', sans-serif;
    }

    /* --- Les Triangles (Rouge, Noir, Gris) --- */
    .top:before, .top:after, .bottom:before, .bottom:after {
        content: '';
        display: block;
        position: absolute;
        width: 200vmax;
        height: 200vmax;
        top: 50%; left: 50%;
        margin-top: -100vmax;
        transform-origin: 0 50%;
        transition: all 0.7s cubic-bezier(0.445, 0.05, 0, 1);
        z-index: 10;
        opacity: 0.9;
    }

    .top:before { transform: rotate(45deg); background: #d32f2f; }   /* Rouge vif */
    .top:after { transform: rotate(135deg); background: #000000; }   /* Noir intense */
    .bottom:before { transform: rotate(-45deg); background: #b71c1c; } /* Rouge sombre */
    .bottom:after { transform: rotate(-135deg); background: #212121; } /* Gris anthracite */

    /* Animation au survol */
    .container-animation:hover .top:before, .container-animation:hover .top:after,
    .container-animation:hover .bottom:before, .container-animation:hover .bottom:after {
        margin-left: 300px; 
        transform-origin: -300px 50%;
    }

    /* --- Bloc Central --- */
    .center {
        position: absolute;
        width: 350px;
        top: 50%; left: 50%;
        transform: translate(-50%, -50%);
        display: flex;
        flex-direction: column;
        align-items: center;
        padding: 20px;
        opacity: 0;
        transition: all 0.5s ease;
        z-index: 5;
        text-align: center;
    }

    .container-animation:hover .center {
        opacity: 1;
        transition-delay: 0.3s;
    }

    .center h2 {
        color: #d32f2f;
        text-transform: uppercase;
        letter-spacing: 2px;
    }

    .form-connexion {
        width: 100%;
        margin-top: 20px;
    }

    /* --- Champs de saisie --- */
    .input-group { width: 100%; }

    .input-group input {
        width: 100%;
        padding: 12px 15px;
        margin-bottom: 15px;
        border: 1px solid #ddd;
        border-radius: 4px;
        font-family: inherit;
        outline: none;
        transition: border-color 0.3s;
    }

    .input-group input:focus {
        border-color: #b71c1c;
    }

    /* --- Bouton Style RoyalBlue (adapté Rouge) --- */
    .btn-submit-box {
        border: none;
        display: block;
        width: 100%;
        position: relative;
        padding: 0.8em;
        font-size: 16px;
        background: transparent;
        cursor: pointer;
        color: #b71c1c;
        font-weight: 700;
        overflow: hidden;
        text-transform: uppercase;
        letter-spacing: 1px;
    }

    .btn-submit-box span {
        position: absolute;
        left: 0; top: 0; width: 100%; height: 100%;
        z-index: -1;
        border: 3px solid #b71c1c;
        box-sizing: border-box;
    }

    .btn-submit-box span::before {
        content: "";
        display: block;
        position: absolute;
        width: 10%; height: 500%;
        background: #f8f8f8;
        top: 50%; left: 50%;
        transform: translate(-50%, -50%) rotate(-60deg);
        transition: all 0.4s;
    }

    .btn-submit-box:hover span::before {
        transform: translate(-50%, -50%) rotate(-90deg);
        width: 100%;
        background: #b71c1c;
    }

    .btn-submit-box:hover { color: white !important; }

    /* --- Liens et erreurs --- */
    .link-switch { margin-top: 20px; font-size: 0.9em; color: #666; }
    .link-switch a { color: #b71c1c; text-decoration: none; font-weight: bold; }
    .error-box { color: #d32f2f; margin-top: 15px; font-size: 0.85em; font-weight: bold; }