style.css

:root {
    --blue: #1877F2;
    --light-blue: #4A90E2;
    --white: #E4E6EB;
    --bg-dark: #18191A;
    --bg-light: #242526;
    --box-shadow: 0 2px 10px rgba(0, 0, 0, 0.5);
    --light-color: #B0BEC5;
}

* {
    font-family: 'Nunito', sans-serif;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    outline: none;
    border: none;
    text-decoration: none;
}

html {
    overflow-x: hidden;
}

body {
    background: linear-gradient(135deg, #1C1C1E, #57575d);
    color: var(--white);
}

.content {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh; 
}

.content .box {
    width: 500px;
    background-color: var(--bg-light);
    border-radius: 5px;
    box-shadow: var(--box-shadow);
}

.div1 {
    padding: 20px 10px;
    display: flex;
    justify-content: space-between;
    background: rgba(255, 255, 255, 0.1);
}

.div2 {
    padding: 20px;
    background: rgba(255, 255, 255, 0.05);
    height: 300px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 3px;
    position: relative;
}

.no-messages {
    text-align: center;
    color: var(--light-color);
    font-style: italic;
    opacity: 0.7;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    display: none;
}

.sms1, .sms2 {
    max-width: 70%;
    margin-bottom: 10px;
    padding: 10px;
    border-radius: 15px;
}

.sms1 {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--blue), var(--light-blue));
    color: var(--white);
    border-radius: 15px 15px 0 15px;
}

.sms2 {
    align-self: flex-start;
    background: #3A3B3C;
    color: var(--white);
    border-radius: 15px 15px 15px 0;
}

#sendBtn, #clearBtn {
    background: var(--blue);
    color: var(--white);
    border-radius: 6px;
    padding: 10px 16px;
    font-weight: bold;
    cursor: pointer;
    transition: 0.4s ease;
}

#sendBtn:hover, #clearBtn:hover {
    background: var(--light-blue);
}

select {
    padding: 10px;
    border-radius: 6px;
    border: 2px solid #a3a3a3;
    margin-right: 10px;
    font-size: 14px;
    background: #3A3B3C;
    color: var(--white);
    cursor: pointer;
}

@media screen and (max-width: 600px) {
    .content .box {
        width: 90%;
    }
}

textarea {
    width: calc(100% - 100px);
    padding: 15px 15px 0px;
    border: 2px solid transparent;
    border-radius: 6px;
    background: transparent;
    color: var(--white);
    margin-right: 10px;
    resize: none;
}

.div3 {
    display: flex;
    align-items: center;
    padding: 10px;
    background: rgba(255, 255, 255, 0.1);
}