body {
    font-family: Arial, sans-serif;
    margin: 0;
    background-color: #252934;
    color: #fff;
}

header {
    background-color: #2d2f3a;
    color: #fff;
    text-align: center;
    padding: 20px;
}

h1 {
    margin: 0;
    font-size: 2em;
}

p {
    margin: 10px 0;
}

input[type="file"] {
    display: block;
    margin: 10px auto;
}

main {
    padding: 20px;
}

#tabs {
    display: flex;
    flex-direction: column;
}

button:not(.excluded-button) {
    background-color: #2d2f3a;
    color: #fff;
    border: none;
    border-radius: 20px;
    padding: 10px;
    margin: 5px;
    width: 100%;
    text-align: left;
    font-size: 1.2em;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

button:hover {
    background-color: #1a1c24;
    color: #F7DF1E;
}

.tab-content {
    display: none;
    padding: 10px;
}

.received-chat, .sent-chat {
    margin: 5px 0;
    padding: 10px;
    border-radius: 20px;
    font-size: 1.1em;
    line-height: 1.5;
}

.received-chat {
    background-color: #41475a;
    color: #fff;
}

.sent-chat {
    background-color: #F7DF1E;
    color: #000;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.chat-time {
    color: #666;
    font-size: 0.8em;
    margin-right: 0.5em;
}