style.css

body {
    background-color: black;
    margin: 0;
    padding: 0;
    background: url('/bg.jpg') no-repeat center fixed;
    background-size: cover;
    box-sizing: border-box;
}
#header {
    background: linear-gradient(45deg, rgb(102, 45, 167), rgb(0, 0, 0), rgb(145, 41, 64));
    backdrop-filter: blur(120px);
    color: white;
    text-align: center;
    margin-bottom: 20px;
    height: 80px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-bottom-left-radius: 20px;
    border-bottom-right-radius: 20px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.5);
    padding: 0 15px;
}
#header::after {
    content: "Welcome to Tic-Tac-Toe Game..!";
    font-weight: 600;
    margin: 0;
    padding: 5px 2px;
    font-family: cursive;
    font-size: 2rem;
    letter-spacing: 2px;
    text-shadow: 0 0 10px #d05ce7, 0 0 20px #9df7fa, 0 0 30px #d895c7, 0 0 40px #69f7d3;
    animation-name: animatingText;
    animation-duration: 1.5s;
    animation-iteration-count: 1;
}

@keyframes animatingText {
    0% {content: "Welcome";}
    15% {content: "Welcome to";}
    30% {content: "Welcome to Tic";}
    45% {content: "Welcome to Tic-Tac";}
    60% {content: "Welcome to Tic-Tac-Toe";}
    75% {content: "Welcome to Tic-Tac-Toe Game";}
    90% {content: "Welcome to Tic-Tac-Toe Game..";}
    100% {content: "Welcome to Tic-Tac-Toe Game..!";}
}

#options {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 70vh;
    padding: 0 20px;
}
#logo {
    height: 150px;
    border-radius: 40px;
    margin-bottom: 20px;
    max-width: 100%;
}
.btn {
    width: 350px;
    padding: 20px 10px;
    margin: 15px 0;
    font-size: 20px;
    font-weight: 1000;
    font-family: cursive;
    background: linear-gradient(45deg, #ff416c, #ff4b2b);
    border: none;
    border-radius: 100px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    position: relative;
    z-index: 1;
    overflow: hidden;
}
.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 200%;
    height: 100%;
    background: rgba(255, 255, 255, 0.3);
    transition: all 0.2s ease;
    transform: skewX(0deg);
    z-index: -1;
}
.btn:hover::before {
    left: 100%;
}
.btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4);
    border: 2px solid black;
}

@media (max-width: 768px) {
    .btn {
        font-size: 19px;
    }

    #header::after {
        font-size: 1.5rem;
    }
}

@media (max-width: 480px) {
    #logo {
        height: 120px;
    }

    .btn {
        width: 100%;
        max-width: 300px;
        font-size: 18px;
    }

    #header::after {
        font-size: 1.3rem;
    }
}

@media (max-width: 350px) {
    .btn {
        font-size: 17px;
        width: 100%;
        max-width: 280px;
    }

    #header::after {
        font-size: 1.1rem;
    }
}