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

:root {
    --talk-blue: #007AFF;
    --talk-dark-blue: #0056CC;
    --text-primary: #1D1D1F;
    --text-secondary: #86868B;
    --border-color: #F0F0F5;
    --bg-color: #F8F9FA;
    --white: #FFFFFF;
    --card-bg: #FFFFFF;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.08);
}

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

.screen {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.auth-container {
    background: var(--white);
    padding: 50px 40px;
    border-radius: 24px;
    width: 92%;
    max-width: 420px;
    box-shadow: var(--shadow-md);
}

.auth-header {
    text-align: center;
    margin-bottom: 30px;
}

.app-logo {
    width: 100px;
    height: 100px;
    border-radius: 50%;
    display: block;
    object-fit: cover;
    margin: 0 auto 20px;
    box-shadow: var(--shadow-sm);
}

.auth-header h1 {
    color: var(--text-primary);
    font-size: 2rem;
    margin-bottom: 8px;
    font-weight: 700;
}

.auth-header p {
    color: var(--text-secondary);
    font-size: 1rem;
}

.auth-tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.auth-tabs button {
    flex: 1;
    padding: 12px;
    border: none;
    background: none;
    font-size: 1rem;
    color: var(--text-secondary);
    cursor: pointer;
    position: relative;
}

.auth-tabs button.active {
    color: var(--talk-blue);
}

.auth-tabs button.active::after {
    content: '';
    position: absolute;
    bottom: -1px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 3px;
    background: var(--talk-blue);
    border-radius: 1.5px;
}

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

form input {
    padding: 16px 18px;
    border: 2px solid var(--border-color);
    border-radius: 16px;
    font-size: 1rem;
    background: var(--bg-color);
    transition: all 0.3s;
}

form input:focus {
    outline: none;
    border-color: var(--talk-blue);
    background: var(--white);
    box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.1);
}

form button[type="submit"] {
    padding: 16px;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    color: white;
    border: none;
    border-radius: 16px;
    font-size: 1.05rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    box-shadow: var(--shadow-sm);
}

form button[type="submit"]:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 122, 255, 0.35);
}

.error-message {
    color: #FF3B30;
    font-size: 0.85rem;
    text-align: center;
    min-height: 20px;
}

.version-info {
    margin-top: 30px;
    text-align: center;
    font-size: 0.8rem;
    color: var(--text-secondary);
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.version-info span:first-child {
    color: var(--talk-blue);
    font-weight: 600;
}

.copyright {
    font-size: 0.75rem;
}

.main-wrapper {
    display: flex;
    flex-direction: column;
    height: 100vh;
    width: 100%;
    max-width: none;
    margin: 0 auto;
}

.header {
    background: var(--white);
    padding: 16px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: none;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
}

.header-title {
    display: flex;
    align-items: center;
    gap: 10px;
}

.header-logo {
    width: 32px;
    height: 32px;
    border-radius: 50%;
    object-fit: cover;
}

.header h1 {
    font-size: 1.2rem;
    font-weight: 600;
}

.header-info {
    display: flex;
    align-items: center;
    gap: 12px;
}

.uptime {
    font-size: 0.8rem;
    color: var(--text-secondary);
    background: var(--bg-color);
    padding: 4px 10px;
    border-radius: 12px;
}

.version-badge {
    font-size: 0.7rem;
    color: var(--talk-blue);
    background: rgba(0, 122, 255, 0.1);
    padding: 3px 8px;
    border-radius: 8px;
    font-weight: 600;
}

.icon-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-primary);
    cursor: pointer;
    padding: 5px 10px;
}

.main-content {
    flex: 1;
    padding-bottom: 60px;
    background: var(--bg-color);
    overflow-y: auto;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

.search-bar {
    padding: 10px 16px;
    background: var(--white);
}

.search-bar input {
    width: 100%;
    padding: 14px 20px;
    border: none;
    border-radius: 18px;
    font-size: 0.95rem;
    background: var(--bg-color);
    box-shadow: var(--shadow-sm);
}

.search-bar input:focus {
    outline: none;
    background: var(--white);
    border-color: var(--talk-blue);
}

.chat-list,
.contacts-list {
    padding: 0;
}

.chat-item,
.contact-item {
    display: flex;
    align-items: center;
    padding: 12px 18px;
    background: var(--white);
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    transition: all 0.3s;
    margin: 6px 20px;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
}

.chat-item:hover,
.contact-item:hover {
    background: #FAFAFA;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.chat-item .avatar,
.contact-item .avatar {
    width: 58px;
    height: 58px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.4rem;
    font-weight: 600;
    margin-right: 16px;
    flex-shrink: 0;
    box-shadow: var(--shadow-sm);
}

.chat-item .chat-info {
    flex: 1;
    min-width: 0;
}

.chat-item .chat-name {
    font-weight: 500;
    font-size: 1rem;
    margin-bottom: 4px;
}

.chat-item .chat-preview {
    color: var(--text-secondary);
    font-size: 0.85rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.chat-item .chat-time {
    color: var(--text-secondary);
    font-size: 0.75rem;
    flex-shrink: 0;
}

.chat-item .unread-badge {
    background: var(--talk-blue);
    color: white;
    font-size: 0.7rem;
    padding: 2px 6px;
    border-radius: 10px;
    margin-left: 8px;
}

.contact-item .contact-name {
    font-size: 1rem;
    font-weight: 500;
}

.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--white);
    display: flex;
    justify-content: space-around;
    padding: 12px 0 20px;
    border-top: none;
    z-index: 1000;
    box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.06);
    width: 100%;
    max-width: none;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
    padding: 5px 15px;
    cursor: pointer;
    color: var(--text-secondary);
    transition: color 0.3s;
}

.nav-item.active {
    color: var(--talk-blue);
}

.nav-icon {
    font-size: 1.4rem;
}

.nav-item span:last-child {
    font-size: 0.7rem;
}

.chat-view {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--bg-color);
    z-index: 2000;
    display: flex;
    flex-direction: column;
    width: 100%;
    max-width: none;
}

.chat-header {
    background: var(--white);
    padding: 10px 16px;
    display: flex;
    align-items: center;
    gap: 10px;
    border-bottom: 1px solid var(--border-color);
}

.chat-header #back-btn,
.chat-header #group-back-btn {
    font-size: 2rem;
    color: var(--text-primary);
}

.chat-header #chat-friend-name,
.chat-header #group-chat-name {
    flex: 1;
    font-size: 1.1rem;
    font-weight: 600;
    text-align: center;
}

.messages-container {
    flex: 1;
    padding: 15px;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.message {
    max-width: 65%;
    padding: 8px 14px;
    border-radius: 16px;
    line-height: 1.4;
    position: relative;
    box-shadow: var(--shadow-sm);
}

.message.sent {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    color: white;
    border-bottom-right-radius: 6px;
}

.message.received {
    align-self: flex-start;
    background: var(--white);
    color: var(--text-primary);
    border-bottom-left-radius: 6px;
}

.message-time {
    font-size: 0.65rem;
    opacity: 0.7;
    margin-top: 4px;
    text-align: right;
}

.message-input-area {
    background: var(--white);
    padding: 12px 16px;
    display: flex;
    align-items: center;
    gap: 10px;
    border-top: 1px solid var(--border-color);
    width: 100%;
    box-shadow: 0 -2px 8px rgba(0, 0, 0, 0.04);
}

.message-input-area #message-input,
.message-input-area #group-message-input {
    flex: 1;
    padding: 12px 18px;
    border: 1px solid var(--border-color);
    border-radius: 25px;
    font-size: 1rem;
    background: var(--bg-color);
    min-height: 44px;
}

.message-input-area #message-input:focus,
.message-input-area #group-message-input:focus {
    outline: none;
    border-color: var(--talk-blue);
    background: var(--white);
}

.send-btn {
    width: auto;
    height: 44px;
    padding: 0 24px;
    border-radius: 22px;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    color: white;
    border: none;
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s;
    box-shadow: 0 2px 8px rgba(0, 122, 255, 0.3);
}

.send-btn:hover {
    transform: scale(1.05);
    box-shadow: 0 4px 12px rgba(0, 122, 255, 0.5);
}

.fab-btn {
    position: fixed;
    bottom: 80px;
    right: 20px;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    color: white;
    font-size: 2rem;
    border: none;
    box-shadow: 0 4px 12px rgba(0, 122, 255, 0.4);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 3000;
}

.modal-content {
    background: var(--white);
    border-radius: 14px;
    width: 85%;
    max-width: 320px;
    overflow: hidden;
}

.modal-header {
    padding: 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    font-size: 1rem;
    font-weight: 600;
}

.modal-body {
    padding: 20px 16px;
}

.modal-body input {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    font-size: 0.95rem;
}

.modal-body input:focus {
    outline: none;
    border-color: var(--talk-blue);
}

.modal-footer {
    padding: 16px;
    border-top: 1px solid var(--border-color);
}

.modal-footer button {
    width: 100%;
    padding: 12px;
    background: var(--talk-blue);
    color: white;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    cursor: pointer;
}

.update-info {
    background: var(--white);
    margin: 10px 0;
    padding: 20px 16px;
    border-radius: 0;
}

.update-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 15px;
    padding-bottom: 10px;
    border-bottom: 1px solid var(--border-color);
}

.update-logo {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    object-fit: cover;
}

.update-header h3 {
    font-size: 1rem;
    color: var(--text-primary);
}

.update-content {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.update-item {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.discover-list {
    margin-top: 10px;
}

.discover-item {
    display: flex;
    align-items: center;
    padding: 14px 16px;
    background: var(--white);
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
}

.discover-item:hover {
    background: #F5F5F5;
}

.discover-icon {
    font-size: 1.3rem;
    margin-right: 12px;
}

.discover-item span:nth-child(2) {
    flex: 1;
    font-size: 0.95rem;
}

.discover-item .arrow {
    color: var(--text-secondary);
    font-size: 1.2rem;
}

.profile-header {
    background: var(--white);
    padding: 30px 16px;
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 10px;
}

.avatar-large {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.8rem;
    font-weight: bold;
}

.profile-info {
    flex: 1;
}

.profile-name {
    font-size: 1.3rem;
    font-weight: 600;
}

.settings-list {
    background: var(--white);
}

.settings-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 14px 16px;
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
}

.settings-item:hover {
    background: #F5F5F5;
}

.settings-item span:first-child {
    font-size: 0.95rem;
}

.settings-item .arrow {
    color: var(--text-secondary);
}

.footer-info {
    margin-top: 30px;
    padding: 20px;
    text-align: center;
    color: var(--text-secondary);
}

.footer-info p:first-child {
    font-size: 0.85rem;
    margin-bottom: 5px;
}

.footer-info .copyright {
    font-size: 0.75rem;
}

.empty-state {
    text-align: center;
    padding: 40px 20px;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.empty-chat {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
}

/* 加载骨架样式 */
.loading-skeleton {
    display: flex;
    align-items: center;
    padding: 12px 18px;
    background: var(--white);
    border-bottom: 1px solid var(--border-color);
    margin: 6px 20px;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
}

.skeleton-avatar {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
    flex-shrink: 0;
}

.skeleton-info {
    flex: 1;
    margin-left: 12px;
}

.skeleton-name {
    width: 60%;
    height: 16px;
    border-radius: 4px;
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
    margin-bottom: 8px;
}

.skeleton-preview {
    width: 40%;
    height: 12px;
    border-radius: 4px;
    background: linear-gradient(90deg, #f0f0f0 25%, #e0e0e0 50%, #f0f0f0 75%);
    background-size: 200% 100%;
    animation: skeleton-loading 1.5s infinite;
}

@keyframes skeleton-loading {
    0% {
        background-position: 200% 0;
    }
    100% {
        background-position: -200% 0;
    }
}

@media (min-width: 768px) {
    .main-wrapper {
        max-width: none;
        box-shadow: none;
        position: relative;
        width: 100%;
    }
    
    .bottom-nav {
        max-width: none;
        left: 0;
        transform: none;
        width: 100%;
    }
    
    .chat-view {
        max-width: none;
        left: 0;
        transform: none;
        width: 100%;
    }
    
    .modal {
        max-width: 480px;
        left: 50%;
        transform: translateX(-50%);
    }
    
    body {
        background: var(--bg-color);
    }
    
    .auth-container {
        margin: 20px auto;
        max-width: 420px;
    }
}

@media (min-width: 1024px) {
    .main-wrapper {
        max-width: none;
        width: 100%;
    }
    
    .header h1 {
        font-size: 1.3rem;
    }
    
    .nav-item {
        padding: 8px 25px;
    }
    
    .nav-icon {
        font-size: 1.5rem;
    }
    
    .nav-item span:last-child {
        font-size: 0.75rem;
    }
}

@media (max-width: 320px) {
    .nav-item {
        padding: 5px 10px;
    }
    
    .nav-icon {
        font-size: 1.2rem;
    }
    
    .nav-item span:last-child {
        font-size: 0.6rem;
    }
    
    .header-info {
        gap: 8px;
    }
    
    .uptime {
        font-size: 0.7rem;
        padding: 3px 6px;
    }
}

.search-result {
    margin: 10px 20px;
    padding: 15px;
    background: var(--white);
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
}

.search-result-item {
    display: flex;
    align-items: center;
    gap: 12px;
}

.search-result-item .avatar {
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 20px;
    font-weight: 500;
    overflow: hidden;
}

.search-result-item .avatar img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.search-result-info {
    flex: 1;
    font-size: 16px;
    color: var(--text-primary);
}

.add-friend-confirm-btn {
    padding: 8px 16px;
    background: linear-gradient(135deg, var(--talk-blue) 0%, var(--talk-dark-blue) 100%);
    color: white;
    border: none;
    border-radius: 20px;
    font-size: 14px;
    cursor: pointer;
    transition: all 0.3s;
}

.add-friend-confirm-btn:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.add-friend-confirm-btn:active {
    transform: scale(0.95);
}

/* 加载动画 */
.loading-spinner {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

.loading-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    pointer-events: none;
    opacity: 0.8;
}

/* 折叠动画 */
.update-header {
    position: relative;
}

.toggle-arrow {
    position: absolute;
    right: 0;
    transition: transform 0.3s ease;
    font-size: 1.2rem;
}

.update-header.expanded .toggle-arrow {
    transform: rotate(180deg);
}

.update-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, padding 0.3s ease;
}

.update-content.expanded {
    max-height: 2000px;
    padding-top: 10px;
}

/* 深色模式 */
body.dark-mode {
    --text-primary: #FFFFFF;
    --text-secondary: #98989D;
    --border-color: #38383A;
    --bg-color: #1C1C1E;
    --white: #2C2C2E;
    --card-bg: #2C2C2E;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.5);
}

body.dark-mode .chat-item:hover,
body.dark-mode .contact-item:hover,
body.dark-mode .discover-item:hover,
body.dark-mode .settings-item:hover {
    background: #3A3A3C;
}

body.dark-mode .message.received {
    background: #3A3A3C;
}

/* 深色模式开关样式 */
.toggle-switch {
    position: relative;
    width: 48px;
    height: 26px;
    display: inline-block;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: 0.3s;
    border-radius: 26px;
}

.toggle-slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: 0.3s;
    border-radius: 50%;
    box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.toggle-switch input:checked + .toggle-slider {
    background-color: var(--talk-blue);
}

.toggle-switch input:checked + .toggle-slider:before {
    transform: translateX(22px);
}

/* 深色模式下的开关 */
body.dark-mode .toggle-slider {
    background-color: #555;
}

.create-group-btn {
    padding: 8px 12px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 0.85rem;
    cursor: pointer;
    white-space: nowrap;
}

.group-item {
    border-left: 3px solid #667eea;
}

.group-members-list {
    max-height: 200px;
    overflow-y: auto;
    margin-bottom: 15px;
}

.group-member-item {
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.group-actions {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.group-action-btn {
    padding: 10px;
    background: var(--talk-blue);
    color: white;
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    cursor: pointer;
}

.group-action-btn.danger {
    background: #ff3b30;
}

.invite-friends-list {
    max-height: 200px;
    overflow-y: auto;
}

.invite-friend-item {
    padding: 10px;
    border-bottom: 1px solid var(--border-color);
}

.invite-friend-item label {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
}

.invite-friend-item input[type="checkbox"] {
    width: 18px;
    height: 18px;
}