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

:root {
    --primary-color: #0084ff;
    --primary-hover: #0073e6;
    --bg-color: #f0f2f5;
    --white: #ffffff;
    --border-color: #e0e0e0;
    --text-primary: #1a1a1a;
    --text-secondary: #65676b;
    --message-sent: #0084ff;
    --message-received: #ffffff;
    --sidebar-width: 320px;
    --header-height: 60px;
    --input-height: 70px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-color);
    height: 100vh;
    height: 100dvh;
    overflow: hidden;
    color: var(--text-primary);
}

/* Auth Screen */
.auth-screen {
    height: 100vh;
    height: 100dvh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 20px;
}

.auth-container {
    background: var(--white);
    border-radius: 16px;
    padding: 40px;
    width: 100%;
    max-width: 420px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.auth-container h2 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--text-primary);
    font-size: 24px;
    font-weight: 700;
}

.tabs {
    display: flex;
    gap: 10px;
    margin-bottom: 25px;
}

.tab {
    flex: 1;
    padding: 12px;
    border: 2px solid #e0e0e0;
    background: transparent;
    cursor: pointer;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all 0.3s;
}

.tab:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.tab.active {
    background: var(--primary-color);
    color: var(--white);
    border-color: var(--primary-color);
}

.auth-form {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.auth-form input {
    padding: 14px 16px;
    border: 2px solid #e8e8e8;
    border-radius: 10px;
    font-size: 16px;
    transition: all 0.3s;
    outline: none;
}

.auth-form input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 132, 255, 0.1);
}

.auth-form button {
    padding: 14px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 10px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.3s;
    margin-top: 5px;
}

.auth-form button:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(0, 132, 255, 0.4);
}

.auth-form button:active {
    transform: translateY(0);
}

.auth-error {
    margin-top: 15px;
    text-align: center;
    font-size: 14px;
    min-height: 20px;
}

/* Chat Layout */
.chat-screen {
    height: 100vh;
    height: 100dvh;
    display: flex;
    justify-content: center;
    align-items: center;
    background: #e8eaed;
    padding: 0;
}

.container {
    display: flex;
    height: 100vh;
    height: 100dvh;
    width: 100%;
    background: var(--white);
}

/* Sidebar */
.sidebar {
    width: var(--sidebar-width);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    background: #f8f9fa;
    flex-shrink: 0;
}

.sidebar-header {
    height: var(--header-height);
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    font-weight: 600;
    font-size: 16px;
    background: var(--white);
}

#current-username {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

#admin-btn {
    background: transparent;
    border: none;
    font-size: 20px;
    cursor: pointer;
    padding: 5px 10px;
    border-radius: 8px;
    transition: background 0.2s;
}

#admin-btn:hover {
    background: #e8e8e8;
}

.users-list {
    flex: 1;
    overflow-y: auto;
    overflow-x: hidden;
}

.users-list::-webkit-scrollbar {
    width: 6px;
}

.users-list::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.user-item {
    padding: 15px 20px;
    cursor: pointer;
    border-bottom: 1px solid #f0f0f0;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 15px;
}

.user-item:hover {
    background: #e8eaed;
}

.user-item.active {
    background: #e7f3ff;
    border-left: 3px solid var(--primary-color);
    padding-left: 17px;
}

.user-item .status {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: #31a24c;
    flex-shrink: 0;
    box-shadow: 0 0 0 3px rgba(49, 162, 76, 0.2);
}

.user-item .username {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* Chat Area */
.chat-area {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    background: var(--white);
}

.chat-header {
    height: var(--header-height);
    padding: 0 20px;
    display: flex;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
    font-weight: 600;
    font-size: 16px;
    background: var(--white);
    flex-shrink: 0;
}

.messages {
    flex: 1;
    overflow-y: auto;
    padding: 20px;
    background: #f5f5f5;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.messages::-webkit-scrollbar {
    width: 6px;
}

.messages::-webkit-scrollbar-thumb {
    background: #ccc;
    border-radius: 3px;
}

.message {
    display: flex;
    flex-direction: column;
    animation: fadeIn 0.3s ease;
}

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

.message.sent {
    align-items: flex-end;
}

.message.received {
    align-items: flex-start;
}

.message-content {
    max-width: 65%;
    padding: 10px 16px;
    border-radius: 18px;
    word-wrap: break-word;
    position: relative;
    line-height: 1.4;
    font-size: 15px;
}

.message.sent .message-content {
    background: var(--message-sent);
    color: var(--white);
    border-bottom-right-radius: 4px;
}

.message.received .message-content {
    background: var(--message-received);
    color: var(--text-primary);
    border-bottom-left-radius: 4px;
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.message-username {
    font-size: 12px;
    color: #65676b;
    margin-bottom: 4px;
    font-weight: 600;
}

.message-time {
    font-size: 11px;
    opacity: 0.7;
    margin-top: 4px;
    text-align: right;
}

.message.sent .message-time {
    color: rgba(255, 255, 255, 0.8);
}

.message.received .message-time {
    color: #65676b;
}

/* Input Area */
.message-input {
    height: var(--input-height);
    padding: 10px 20px;
    background: var(--white);
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: 10px;
    align-items: center;
    flex-shrink: 0;
    position: sticky;
    bottom: 0;
    z-index: 5;
}

.message-input input {
    flex: 1;
    padding: 12px 20px;
    border: 2px solid #e8e8e8;
    border-radius: 24px;
    font-size: 15px;
    outline: none;
    transition: all 0.3s;
    background: #f0f2f5;
}

.message-input input:focus {
    border-color: var(--primary-color);
    background: var(--white);
    box-shadow: 0 0 0 3px rgba(0, 132, 255, 0.1);
}

.message-input input:disabled {
    background: #f5f5f5;
    cursor: not-allowed;
}

#send-btn {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    padding: 0;
    font-size: 20px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    cursor: pointer;
    transition: all 0.3s;
    flex-shrink: 0;
    display: flex;
    align-items: center;
    justify-content: center;
}

#send-btn:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: scale(1.05);
    box-shadow: 0 2px 8px rgba(0, 132, 255, 0.4);
}

#send-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Empty state */
.empty-chat {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #65676b;
    font-size: 18px;
}

.empty-chat-icon {
    font-size: 64px;
    margin-bottom: 20px;
    opacity: 0.3;
}

.empty-chat-text {
    text-align: center;
}

/* Admin Panel Modal */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    height: 100dvh;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    animation: fadeIn 0.3s;
    backdrop-filter: blur(5px);
}

.modal-content {
    background: var(--white);
    border-radius: 16px;
    padding: 30px;
    max-width: 500px;
    width: 90%;
    max-height: 80vh;
    max-height: 80dvh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.modal-content h3 {
    margin-bottom: 20px;
    font-size: 20px;
    color: var(--text-primary);
}

.admin-user-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px;
    border-bottom: 1px solid #f0f0f0;
    gap: 10px;
    flex-wrap: wrap;
}

.admin-user-item:last-child {
    border-bottom: none;
}

.admin-user-item .user-info {
    display: flex;
    align-items: center;
    gap: 8px;
}

.admin-user-item .status-badge {
    font-size: 12px;
    padding: 4px 10px;
    border-radius: 12px;
    font-weight: 600;
}

.status-active {
    background: #e8f5e9;
    color: #2e7d32;
}

.status-inactive {
    background: #fce4ec;
    color: #c62828;
}

.admin-actions {
    display: flex;
    gap: 8px;
}

.toggle-btn {
    padding: 8px 16px;
    border: none;
    border-radius: 8px;
    font-size: 13px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.toggle-btn.activate {
    background: #4caf50;
    color: white;
}

.toggle-btn.activate:hover {
    background: #388e3c;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(76, 175, 80, 0.4);
}

.toggle-btn.deactivate {
    background: #f44336;
    color: white;
}

.toggle-btn.deactivate:hover {
    background: #d32f2f;
    transform: translateY(-1px);
    box-shadow: 0 2px 8px rgba(244, 67, 54, 0.4);
}

.close-btn {
    margin-top: 20px;
    width: 100%;
    padding: 12px;
    background: #f0f2f5;
    border: none;
    border-radius: 10px;
    font-size: 15px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

.close-btn:hover {
    background: #e4e6e9;
}

/* Mobile Back Button */
.mobile-back-btn {
    display: none;
    margin-right: 15px;
    font-size: 20px;
    cursor: pointer;
    padding: 5px;
    border-radius: 8px;
    transition: background 0.2s;
}

.mobile-back-btn:hover {
    background: #e8e8e8;
}

/* Desktop styles (≥ 769px) */
@media (min-width: 769px) {
    .container {
        max-width: 1400px;
        height: calc(100vh - 40px);
        height: calc(100dvh - 40px);
        margin: 20px auto;
        border-radius: 12px;
        box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
        overflow: hidden;
    }

    .chat-screen {
        padding: 20px;
    }

    .message-content {
        max-width: 55%;
    }

    .empty-chat {
        display: flex;
        flex-direction: column;
    }

    .message-input {
        position: static;
    }
}

/* Tablet styles (481px - 768px) */
@media (max-width: 768px) {
    .container {
        position: relative;
    }

    .sidebar {
        width: 100%;
        position: absolute;
        left: 0;
        top: 0;
        height: 100%;
        z-index: 10;
        transition: transform 0.3s ease;
        padding-bottom: env(safe-area-inset-bottom);
    }

    .sidebar.hidden {
        transform: translateX(-100%);
    }

    .chat-area {
        width: 100%;
    }

    .mobile-back-btn {
        display: block;
    }

    .chat-header {
        cursor: default;
        display: flex;
        align-items: center;
    }

    .message-content {
        max-width: 80%;
    }

    .message-input {
        padding: 10px 15px 20px 15px;
        padding-bottom: max(20px, env(safe-area-inset-bottom));
    }

    .users-list {
        padding-bottom: env(safe-area-inset-bottom);
    }
}

/* Mobile styles (≤ 480px) */
@media (max-width: 480px) {
    .auth-container {
        padding: 25px 20px;
        max-height: 90dvh;
        overflow-y: auto;
    }

    .auth-container h2 {
        font-size: 20px;
    }

    .tab {
        padding: 10px;
        font-size: 14px;
    }

    .auth-form input {
        padding: 12px 14px;
        font-size: 16px;
    }

    .auth-form button {
        padding: 12px;
        font-size: 15px;
    }

    .sidebar-header {
        padding: 0 15px;
    }

    .user-item {
        padding: 12px 15px;
        font-size: 14px;
    }

    .chat-header {
        padding: 0 15px;
    }

    .messages {
        padding: 15px;
        gap: 6px;
    }

    .message-content {
        max-width: 85%;
        padding: 8px 12px;
        font-size: 14px;
    }

    .message-input {
        height: auto;
        min-height: 60px;
        padding: 8px 12px 15px 12px;
        padding-bottom: max(15px, env(safe-area-inset-bottom));
        gap: 8px;
        background: var(--white);
        border-top: 1px solid var(--border-color);
        position: sticky;
        bottom: 0;
        z-index: 5;
    }

    .message-input input {
        padding: 10px 16px;
        font-size: 16px;
    }

    #send-btn {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }

    .modal-content {
        padding: 20px;
        max-height: 80dvh;
    }

    .admin-user-item {
        padding: 12px;
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }

    .admin-actions {
        width: 100%;
        justify-content: flex-end;
    }

    .toggle-btn {
        padding: 6px 12px;
        font-size: 12px;
    }
}

/* Landscape mode for mobile */
@media (max-height: 500px) and (orientation: landscape) {
    .auth-container {
        padding: 20px;
        margin: 10px;
        max-height: 100dvh;
    }

    .auth-container h2 {
        margin-bottom: 15px;
        font-size: 18px;
    }

    .tabs {
        margin-bottom: 15px;
    }

    .auth-form {
        gap: 10px;
    }

    .message-content {
        max-width: 70%;
    }

    .message-input {
        min-height: 50px;
        padding: 5px 15px 10px 15px;
    }
}

/* Для очень маленьких экранов */
@media (max-width: 320px) {
    .message-input {
        padding: 5px 8px 12px 8px;
    }

    .message-input input {
        padding: 8px 12px;
        font-size: 14px;
    }

    .message-content {
        max-width: 90%;
        font-size: 13px;
    }
}