* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: #0b0e14;
    color: #e0e6ed;
    font-family: system-ui, -apple-system, sans-serif;
    height: 100vh;
    overflow: hidden;
}

.app {
    display: flex;
    height: 100vh;
}

.sidebar {
    width: 220px;
    background: #11161f;
    padding: 20px;
    border-right: 1px solid #1f2a36;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.logo {
    font-size: 18px;
    font-weight: 700;
    color: #ff8c00;
}

.session-list {
    flex: 1;
    overflow-y: auto;
}

.session-item {
    padding: 8px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    color: #8a9aa8;
    transition: background 0.2s;
}

.session-item:hover {
    background: #1f2a36;
}

.session-item.active {
    background: #2a3645;
    color: #fff;
}

.btn-outline {
    background: transparent;
    border: 1px solid #2a3645;
    color: #e0e6ed;
    padding: 8px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
}

.btn-outline:hover {
    background: #1f2a36;
}

.chat {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: #0f141c;
}

.chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 20px;
    border-bottom: 1px solid #1f2a36;
    font-size: 14px;
}

.chat-models label {
    margin-left: 12px;
    color: #8a9aa8;
}

.chat-messages {
    flex: 1;
    padding: 20px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.message {
    display: flex;
    gap: 12px;
    max-width: 80%;
}

.message.user {
    align-self: flex-end;
    flex-direction: row-reverse;
}

.message .avatar {
    width: 32px;
    height: 32px;
    background: #1f2a36;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    flex-shrink: 0;
}

.message.user .avatar {
    background: #ff8c00;
}

.message .content {
    background: #1a222c;
    padding: 10px 14px;
    border-radius: 12px;
    font-size: 14px;
    line-height: 1.5;
    word-break: break-word;
}

.message.user .content {
    background: #2a3645;
}

.chat-input {
    display: flex;
    gap: 10px;
    padding: 12px 20px;
    border-top: 1px solid #1f2a36;
    background: #0f141c;
}

.chat-input textarea {
    flex: 1;
    background: #1a222c;
    border: none;
    padding: 10px 14px;
    border-radius: 8px;
    color: #e0e6ed;
    font-size: 14px;
    resize: none;
    outline: none;
}

.chat-input button {
    background: #ff8c00;
    border: none;
    padding: 0 18px;
    border-radius: 8px;
    color: #0b0e14;
    font-size: 20px;
    font-weight: 700;
    cursor: pointer;
}

.chat-input button:hover {
    background: #e07b00;
}

.panel {
    width: 220px;
    background: #11161f;
    padding: 20px;
    border-left: 1px solid #1f2a36;
    display: flex;
    flex-direction: column;
    gap: 20px;
    font-size: 14px;
}

.panel-section h4 {
    color: #8a9aa8;
    margin-bottom: 8px;
    font-weight: 400;
}

.btn-secondary {
    background: #1f2a36;
    border: none;
    color: #e0e6ed;
    padding: 6px 12px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 13px;
    width: 100%;
    margin-bottom: 6px;
}

.btn-secondary:hover {
    background: #2a3645;
}

#lessonLog {
    color: #8a9aa8;
    font-size: 13px;
}