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

:root {
    --primary-color: #6366f1;
    --secondary-color: #8b5cf6;
    --danger-color: #ef4444;
    --success-color: #22c55e;
    --background-color: #0f172a;
    --surface-color: #1e293b;
    --border-color: #334155;
    --text-color: #f1f5f9;
    --text-muted: #94a3b8;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

/* ===== Welcome / Home Page ===== */
.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}

.welcome-section {
    text-align: center;
}

.welcome-section h1 {
    font-size: 3.5rem;
    margin-bottom: 10px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
}

.subtitle {
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-bottom: 40px;
}

.settings-section {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 30px;
    margin-bottom: 20px;
}

.settings-section h2 {
    font-size: 1.3rem;
    margin-bottom: 20px;
    text-align: left;
}

.setting-group {
    margin-bottom: 20px;
    text-align: left;
}

.setting-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-color);
}

.setting-group select {
    width: 100%;
    padding: 10px 12px;
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-color);
    font-size: 1rem;
    cursor: pointer;
    transition: border-color 0.2s;
}

.setting-group select:hover,
.setting-group select:focus {
    border-color: var(--primary-color);
    outline: none;
}

.loading {
    text-align: center;
    padding: 30px;
}

.loading.hidden {
    display: none;
}

.spinner {
    width: 40px;
    height: 40px;
    margin: 0 auto 15px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.error-message {
    background-color: rgba(239, 68, 68, 0.1);
    border: 1px solid var(--danger-color);
    color: #fca5a5;
    padding: 15px;
    border-radius: 8px;
    margin-top: 15px;
}

.error-message.hidden {
    display: none;
}

/* ===== Buttons ===== */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    text-transform: none;
    white-space: nowrap;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: #4f46e5;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
    background-color: var(--surface-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: #475569;
    border-color: var(--primary-color);
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
}

.btn-danger:hover {
    background-color: #dc2626;
}

.btn-large {
    width: 100%;
    padding: 16px;
    font-size: 1.1rem;
    margin-top: 20px;
}

.btn-small {
    padding: 8px 16px;
    font-size: 0.9rem;
}

.btn-block {
    width: 100%;
}

.btn:active {
    transform: scale(0.98);
}

/* ===== Chat Container ===== */
.chat-container {
    display: flex;
    flex-direction: column;
    height: 100vh;
    background-color: var(--background-color);
    overflow: hidden;
}

.chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background-color: var(--surface-color);
    border-bottom: 1px solid var(--border-color);
    padding: 15px 20px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.header-left {
    display: flex;
    align-items: center;
    gap: 20px;
}

.header-left h1 {
    font-size: 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.chat-info {
    display: flex;
    gap: 10px;
}

.info-badge {
    background-color: var(--background-color);
    padding: 5px 12px;
    border-radius: 12px;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.header-right {
    display: flex;
    gap: 10px;
}

.chat-content {
    display: flex;
    flex: 1;
    overflow: hidden;
}

/* ===== Sidebar ===== */
.chat-sidebar {
    width: 200px;
    background-color: var(--surface-color);
    border-right: 1px solid var(--border-color);
    padding: 15px;
    overflow-y: auto;
    flex-shrink: 0;
}

.sidebar-header {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-muted);
    text-transform: uppercase;
    margin-bottom: 12px;
    letter-spacing: 0.5px;
}

.participants-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.participant-item {
    padding: 8px 12px;
    background-color: var(--background-color);
    border-radius: 6px;
    font-size: 0.9rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    color: var(--text-color);
    border: 1px solid transparent;
    transition: all 0.2s;
}

.participant-item:hover {
    background-color: rgba(99, 102, 241, 0.1);
    border-color: var(--primary-color);
}

.participant-item.current {
    background-color: rgba(99, 102, 241, 0.2);
    border-color: var(--primary-color);
    color: var(--primary-color);
    font-weight: 500;
}

/* ===== Main Chat Area ===== */
.chat-main {
    display: flex;
    flex-direction: column;
    flex: 1;
    overflow: hidden;
}

.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.message {
    display: flex;
    margin-bottom: 15px;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.message-content {
    background-color: var(--surface-color);
    border-left: 3px solid var(--primary-color);
    padding: 12px 15px;
    border-radius: 6px;
    max-width: 70%;
}

.message.own {
    justify-content: flex-end;
}

.message.own .message-content {
    background-color: var(--primary-color);
    border-left: none;
    border-right: 3px solid var(--secondary-color);
}

.message-nickname {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 4px;
    font-weight: 600;
}

.message.own .message-nickname {
    color: rgba(255, 255, 255, 0.7);
}

.message-text {
    word-wrap: break-word;
    white-space: pre-wrap;
    font-size: 0.95rem;
}

.message-time {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 4px;
}

.message.own .message-time {
    color: rgba(255, 255, 255, 0.5);
}

.system-message {
    text-align: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    padding: 10px;
    margin: 10px 0;
    font-style: italic;
}

/* ===== Chat Input ===== */
.chat-input-area {
    padding: 20px;
    background-color: var(--surface-color);
    border-top: 1px solid var(--border-color);
    flex-shrink: 0;
}

.message-input {
    width: 100%;
    padding: 12px;
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-color);
    font-size: 0.95rem;
    font-family: inherit;
    resize: vertical;
    min-height: 60px;
    max-height: 150px;
    transition: border-color 0.2s;
}

.message-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.input-buttons {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 12px;
}

.char-count {
    font-size: 0.85rem;
    color: var(--text-muted);
}

/* ===== Modal ===== */
.modal {
    display: flex;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.6);
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.2s ease-out;
}

.modal.hidden {
    display: none;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

.modal-content {
    background-color: var(--surface-color);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    max-width: 500px;
    width: 90%;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-size: 1.3rem;
}

.modal-close {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: color 0.2s;
}

.modal-close:hover {
    color: var(--danger-color);
}

.modal-body {
    padding: 20px;
}

.modal-body p {
    margin-bottom: 15px;
    color: var(--text-muted);
}

.chat-link-input {
    width: 100%;
    padding: 12px;
    background-color: var(--background-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--text-color);
    font-size: 0.9rem;
    margin-bottom: 15px;
    cursor: text;
}

.chat-link-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* ===== Notifications ===== */
.notification {
    position: fixed;
    bottom: 20px;
    right: 20px;
    padding: 15px 20px;
    border-radius: 8px;
    z-index: 999;
    animation: slideInRight 0.3s ease-out;
}

.notification.hidden {
    display: none;
}

@keyframes slideInRight {
    from {
        transform: translateX(400px);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

.notification.error {
    background-color: rgba(239, 68, 68, 0.9);
    border: 1px solid var(--danger-color);
    color: white;
}

.notification.success {
    background-color: rgba(34, 197, 94, 0.9);
    border: 1px solid var(--success-color);
    color: white;
}

/* ===== Responsive Design ===== */
@media (max-width: 768px) {
    .chat-sidebar {
        width: 150px;
    }

    .chat-header {
        flex-wrap: wrap;
        gap: 10px;
    }

    .header-left {
        width: 100%;
        gap: 10px;
    }

    .header-left h1 {
        font-size: 1.2rem;
    }

    .header-right {
        width: 100%;
    }

    .message-content {
        max-width: 85%;
    }

    .message-input {
        min-height: 50px;
    }
}

@media (max-width: 600px) {
    .chat-content {
        flex-direction: column;
    }

    .chat-sidebar {
        width: 100%;
        border-right: none;
        border-bottom: 1px solid var(--border-color);
        max-height: 120px;
        overflow-x: auto;
        overflow-y: hidden;
        flex-direction: row;
        padding: 10px;
    }

    .participants-list {
        flex-direction: row;
        gap: 8px;
        overflow-x: auto;
    }

    .participant-item {
        flex-shrink: 0;
    }

    .message-content {
        max-width: 100%;
    }

    .modal-content {
        width: 95%;
    }
}

/* ===== Scrollbar Styling ===== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--surface-color);
}

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}