* {
    box-sizing: border-box;
}

body {
    margin: 0;
    background: #c5d9ed;
    font-family: Tahoma, Arial, sans-serif;
    color: #243c57;
}

.topbar {
    background: linear-gradient(#bde4ff, #4b9bd5);
    padding: 18px;
    color: white;
    border-bottom: 3px solid #3279b7;
    text-shadow: 1px 1px #356b9d;
}

.topbar h1 {
    margin: 0;
    font-size: 24px;
}

.subtitle {
    font-size: 12px;
    margin-top: 4px;
}

.container {
    max-width: 650px;
    margin: 25px auto;
    padding: 0 12px;
}

.panel {
    background: #f5f9fd;
    border: 1px solid #91b8d8;
    border-radius: 9px;
    overflow: hidden;
    box-shadow: 0 3px 12px #6688a555;
}

.panel-title {
    background: linear-gradient(#e4f4ff, #b6d9f4);
    padding: 12px;
    border-bottom: 1px solid #91b8d8;
    font-weight: bold;
}

.messages {
    padding: 15px;
    min-height: 300px;
}

.message {
    max-width: 85%;
    margin-bottom: 13px;
    padding: 10px 13px;
    border-radius: 10px;
    background: #e4edf7;
    border: 1px solid #c0d2e4;
    overflow-wrap: anywhere;
}

.message.mine {
    margin-left: auto;
    background: #d2edff;
    border-color: #91c7e9;
}

.sender {
    font-size: 12px;
    font-weight: bold;
    color: #3278ad;
    margin-bottom: 5px;
}

.time {
    font-size: 10px;
    color: #778da2;
    text-align: right;
    margin-top: 5px;
}

.composer {
    padding: 12px;
    display: flex;
    gap: 8px;
    background: #e6f1fa;
    border-top: 1px solid #b5cee3;
}

input {
    min-width: 0;
    padding: 11px;
    border: 1px solid #9dbbd4;
    border-radius: 5px;
    font-size: 15px;
}

.composer input[type="text"] {
    flex: 1;
}

button {
    border: 1px solid #347eb6;
    border-radius: 5px;
    padding: 10px 16px;
    background: linear-gradient(#a8dcff, #529bd1);
    color: white;
    font-weight: bold;
    cursor: pointer;
}

.login-box {
    padding: 20px;
}

.login-box input {
    width: 100%;
    margin: 7px 0 15px;
}

.login-box button {
    width: 100%;
}

.footer {
    padding: 12px;
    text-align: center;
    font-size: 11px;
    color: #66809a;
}

.toolbar {
    padding: 10px;
    font-size: 13px;
}

a {
    color: #287bb7;
}