.welcome-container {
    text-align: center;
    margin-top: 100px;
}

#welcome-text {
    overflow: hidden;
    border-right: 0.15em solid orange; /* アニメーション用の仮のボーダー */
    white-space: nowrap;
    margin: 0;
    letter-spacing: 0.15em;
    animation:
        typing 3.5s steps(40, end),
        blink-caret 0.5s step-end infinite;
}

@keyframes typing {
    from { width: 0 }
    to { width: 100% }
}

@keyframes blink-caret {
    from, to { border-color: transparent }
    50% { border-color: orange; }
}