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

:root {
    --text: #1d2129;
    --text-2: #4e5969;
    --text-3: #86909c;
    --line: #e5e6eb;
    --fill: #f2f3f5;
    --sidebar: #f7f8fa;
    --page: #ffffff;
    --blue: #165dff;
    --blue-hover: #0e42d2;
    --shadow: 0 8px 24px rgba(29, 33, 41, 0.06);
    --font: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
    --ease: cubic-bezier(0.645, 0.045, 0.355, 1);
    --ease-out: cubic-bezier(0.215, 0.61, 0.355, 1);
    --ease-drawer: cubic-bezier(0.78, 0.14, 0.15, 0.86);
    --fast: 0.1s;
    --mid: 0.2s;
    --slow: 0.3s;
}

html,
body {
    height: 100%;
}

body {
    font-family: var(--font);
    font-size: 14px;
    color: var(--text);
    background: var(--page);
    overflow: hidden;
}

button,
input,
textarea,
select {
    font-family: inherit;
    font-size: 14px;
    color: inherit;
}

.app-container {
    display: flex;
    height: 100vh;
    width: 100vw;
    background: var(--page);
}

.sidebar {
    width: 260px;
    background: var(--sidebar);
    display: flex;
    flex-direction: column;
    padding: 16px 12px 16px;
    flex-shrink: 0;
    min-height: 0;
    overflow-y: auto;
    transition: background-color var(--slow) var(--ease);
}

.sidebar-header {
    padding: 4px 8px 14px;
}

.sidebar-header h2 {
    font-size: 16px;
    font-weight: 600;
    letter-spacing: 0;
}

.brand-sub {
    margin-top: 2px;
    font-size: 12px;
    color: var(--text-3);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    border: none;
    background: transparent;
    cursor: pointer;
    border-radius: 8px;
    line-height: 1;
    transition: background-color var(--mid) var(--ease), color var(--mid) var(--ease), transform var(--fast) var(--ease-out), opacity var(--mid) var(--ease);
}

.btn-primary {
    height: 40px;
    padding: 0 12px;
    justify-content: flex-start;
    color: var(--text);
    font-weight: 500;
    border-radius: 10px;
}

.btn-primary::before {
    content: "+";
    font-size: 18px;
    font-weight: 400;
    width: 18px;
    text-align: center;
}

.btn-primary:hover,
.btn-secondary:hover,
.session-btn:hover {
    background: #eceef1;
}

.btn-active,
.session-btn.btn-active {
    background: #e8eaed;
}

.btn-full {
    width: 100%;
    margin-bottom: 8px;
}

.btn-ghost,
.btn-theme {
    height: 32px;
    padding: 0 10px;
    color: var(--text-2);
    font-size: 13px;
    border-radius: 8px;
    background: transparent;
    border: none;
    cursor: pointer;
}

.btn-ghost:hover,
.btn-theme:hover {
    background: var(--fill);
    color: var(--text);
}

.btn-send {
    width: 32px;
    height: 32px;
    padding: 0;
    border-radius: 50%;
    background: var(--blue);
    color: #fff;
    flex-shrink: 0;
}

.btn-send:hover {
    background: var(--blue-hover);
}

.btn-send:active,
.btn-send.is-pressed {
    transform: scale(0.9);
}

.btn-send.is-idle:not(.is-busy) {
    background: #e5e6eb;
    color: #fff;
}

.btn-send.is-idle:not(.is-busy):hover,
.btn-send.is-idle:not(.is-busy):active,
.btn-send.is-idle.is-pressed:not(.is-busy) {
    background: #e5e6eb;
    transform: none;
}

.btn-send:disabled,
.btn-send.is-busy {
    opacity: 0.55;
    cursor: default;
    transform: none;
}

.btn-icon {
    width: 22px;
    height: 22px;
    padding: 0;
    border: none;
    border-radius: 6px;
    background: transparent;
    color: var(--text-3);
    font-size: 15px;
    opacity: 0;
    cursor: pointer;
    transition: opacity var(--mid) var(--ease), color var(--mid) var(--ease), transform var(--fast) var(--ease-out);
}

.session-item:hover .btn-icon,
.session-item:focus-within .btn-icon {
    opacity: 1;
}

.btn-icon:hover {
    color: #f53f3f;
    background: transparent;
}

.session-section h3,
.companion-section h3,
.info-section h3 {
    font-size: 12px;
    font-weight: 500;
    color: var(--text-3);
    margin: 14px 8px 6px;
}

.session-list {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.session-item {
    display: flex;
    align-items: center;
}

.session-btn {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    padding: 8px 10px;
    border: none;
    border-radius: 8px;
    background: transparent;
    text-align: left;
    cursor: pointer;
    color: var(--text);
    font-family: inherit;
    transition: background-color var(--mid) var(--ease), transform var(--fast) var(--ease-out);
}

.session-btn:active,
.session-btn.is-pressed,
.btn-primary:active,
.btn-primary.is-pressed,
.btn-ghost:active,
.btn-theme:active,
.theme-option:active {
    transform: scale(0.98);
}

.session-btn .session-title {
    width: 100%;
    font-size: 14px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.session-btn .session-time,
.session-btn.btn-active .session-time {
    font-size: 12px;
    color: var(--text-3);
}

.companion-section {
    margin-top: 8px;
    padding-top: 4px;
}

.form-group {
    margin: 0 4px 10px;
}

.form-group label {
    display: block;
    margin-bottom: 4px;
    font-size: 12px;
    color: var(--text-3);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 8px 10px;
    border: 1px solid transparent;
    border-radius: 8px;
    background: #fff;
    resize: vertical;
    transition: border-color var(--mid) var(--ease), box-shadow var(--mid) var(--ease), background-color var(--slow) var(--ease);
}

.form-group textarea {
    min-height: 72px;
    line-height: 1.55;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: #94bfff;
    box-shadow: 0 0 0 2px rgba(22, 93, 255, 0.15);
}

.field-hint {
    margin: 0 6px;
    font-size: 12px;
    line-height: 1.5;
    color: var(--text-3);
    transition: color var(--mid) var(--ease);
}

.field-hint.is-notice {
    color: var(--blue);
}

.chat-container {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    background: var(--page);
    transition: background-color var(--slow) var(--ease);
}

.chat-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 56px;
    padding: 0 16px 0 20px;
    flex-shrink: 0;
}

.chat-header h1 {
    font-size: 15px;
    font-weight: 600;
}

.session-name {
    display: block;
    margin-top: 2px;
    font-size: 12px;
    color: var(--text-3);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 2px;
}

.theme-switcher {
    position: relative;
}

.theme-dropdown {
    position: absolute;
    top: 36px;
    right: 0;
    min-width: 128px;
    padding: 6px;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 12px;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.08);
    z-index: 20;
    opacity: 0;
    transform: scale(0.85);
    transform-origin: top right;
    visibility: hidden;
    pointer-events: none;
    transition: opacity var(--mid) var(--ease-out), transform var(--mid) var(--ease-out), visibility var(--mid);
}

.theme-dropdown.show {
    opacity: 1;
    transform: scale(1);
    visibility: visible;
    pointer-events: auto;
}

.theme-option {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 10px;
    border-radius: 8px;
    font-size: 13px;
    cursor: pointer;
    transition: background-color var(--mid) var(--ease);
}

.theme-option:hover,
.theme-option.active {
    background: var(--fill);
}

.theme-color {
    width: 12px;
    height: 12px;
    border-radius: 3px;
    border: 1px solid var(--line);
}

.theme-light { background: #fff; }
.theme-dark { background: #1d2129; }

.chat-body {
    flex: 1;
    min-height: 0;
    width: min(800px, calc(100% - 48px));
    margin: 0 auto;
    position: relative;
    display: flex;
    flex-direction: column;
}

.chat-messages {
    flex: 1;
    min-height: 0;
    width: 100%;
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 22px;
    padding: 8px 0 12px;
}

.jump-bottom {
    position: absolute;
    right: 0;
    bottom: 16px;
    z-index: 2;
    height: 32px;
    padding: 0 12px;
    border: 1px solid var(--line);
    border-radius: 16px;
    background: #fff;
    color: var(--text-2);
    font-size: 13px;
    box-shadow: 0 4px 14px rgba(29, 33, 41, 0.08);
    cursor: pointer;
    transition: background-color var(--mid) var(--ease), color var(--mid) var(--ease), transform var(--fast) var(--ease-out);
}

.jump-bottom[hidden] {
    display: none;
}

.jump-bottom:hover {
    color: var(--text);
    background: #f7f8fa;
}

.chat-messages::-webkit-scrollbar,
.sidebar::-webkit-scrollbar {
    width: 8px;
}

.chat-messages::-webkit-scrollbar-thumb,
.sidebar::-webkit-scrollbar-thumb {
    background: #d9dce3;
    border-radius: 8px;
}

.message {
    display: flex;
    gap: 12px;
    width: 100%;
    align-items: flex-start;
}

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

.message.user .message-avatar {
    display: none;
}

.message-avatar {
    width: 28px;
    height: 28px;
    border-radius: 8px;
    background: #e8f3ff;
    color: var(--blue);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 13px;
    font-weight: 600;
    flex-shrink: 0;
}

.message-content {
    font-size: 16px;
    line-height: 1.75;
    word-wrap: break-word;
    white-space: pre-wrap;
}

.message.is-enter .message-content,
.message.is-enter .message-avatar {
    animation: rise-in var(--slow) var(--ease-out) both;
}

.message.user.is-enter .message-content {
    transform-origin: right center;
}

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

.message.user .message-content {
    max-width: min(520px, 78%);
    padding: 10px 14px;
    background: var(--fill);
    color: var(--text);
    border-radius: 12px;
}

.message.assistant .message-content {
    padding: 2px 0 0;
    color: var(--text);
}

.chat-input-container {
    flex-shrink: 0;
    padding: 8px 24px 22px;
    background: linear-gradient(to top, #fff 72%, rgba(255, 255, 255, 0));
}

.chat-input-wrapper {
    width: min(800px, 100%);
    margin: 0 auto;
    display: flex;
    align-items: flex-end;
    gap: 8px;
    min-height: 56px;
    padding: 8px 8px 8px 18px;
    background: #fff;
    border: 1px solid var(--line);
    border-radius: 20px;
    box-shadow: var(--shadow);
    transition: border-color var(--mid) var(--ease), box-shadow var(--mid) var(--ease), background-color var(--slow) var(--ease);
}

.chat-input-wrapper:focus-within {
    border-color: #94bfff;
    box-shadow: 0 0 0 2px rgba(22, 93, 255, 0.12), 0 8px 24px rgba(22, 93, 255, 0.08);
}

.chat-input {
    flex: 1;
    min-width: 0;
    border: none;
    outline: none;
    resize: none;
    background: transparent;
    font-size: 16px;
    line-height: 24px;
    max-height: 160px;
    padding: 4px 0;
    overflow-y: auto;
}

.chat-input::placeholder {
    color: #c9cdd4;
}

.loading {
    display: flex;
    align-items: center;
    gap: 5px;
    height: 24px;
}

.loading-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--blue);
    animation: wave 1.2s infinite var(--ease) both;
}

.loading-dot:nth-child(2) { animation-delay: 0.16s; }
.loading-dot:nth-child(3) { animation-delay: 0.32s; }

@keyframes wave {
    0%, 80%, 100% { transform: translateY(0); opacity: 0.35; }
    40% { transform: translateY(-4px); opacity: 1; }
}

.empty-state {
    margin: auto;
    width: min(640px, 100%);
    text-align: center;
    padding: 24px 12px 48px;
    animation: rise-in 0.35s var(--ease-out) both;
}

.empty-state-mark {
    display: none;
}

.empty-state-title {
    font-size: 28px;
    font-weight: 600;
    line-height: 1.35;
    color: var(--text);
}

.empty-state-text {
    margin-top: 8px;
    font-size: 15px;
    color: var(--text-3);
}

.starter-list {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px;
    margin-top: 20px;
}

.starter-chip {
    border: 1px solid var(--line);
    background: #fff;
    color: var(--text-2);
    border-radius: 999px;
    padding: 8px 14px;
    font-size: 14px;
    font-family: inherit;
    cursor: pointer;
    transition: border-color var(--mid) var(--ease), color var(--mid) var(--ease), background-color var(--mid) var(--ease), transform var(--fast) var(--ease-out);
}

.starter-chip:hover {
    border-color: #94bfff;
    color: var(--blue);
    background: #f5f8ff;
}

.empty-state-icon {
    display: none;
}

.drawer-mask {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.28);
    opacity: 0;
    z-index: 30;
    pointer-events: none;
    transition: opacity var(--slow) var(--ease);
}

.drawer-mask.is-open {
    opacity: 1;
    pointer-events: auto;
}

.drawer-mask[hidden] {
    display: none !important;
}

.info-sidebar {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: 300px;
    max-width: 90vw;
    background: #fff;
    border-left: 1px solid var(--line);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    z-index: 40;
    transform: translateX(100%);
    transition: transform var(--slow) var(--ease-drawer), background-color var(--slow) var(--ease);
    box-shadow: -8px 0 24px rgba(0, 0, 0, 0.08);
    visibility: hidden;
    pointer-events: none;
}

.info-sidebar.is-open {
    transform: translateX(0);
    visibility: visible;
    pointer-events: auto;
}

.info-sidebar[hidden] {
    display: none !important;
}

.info-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 56px;
    padding: 0 12px 0 16px;
}

.info-header h2 {
    font-size: 15px;
    font-weight: 600;
}

.info-content {
    padding: 4px 16px 20px;
}

.info-section p,
.feature-list li {
    font-size: 14px;
    line-height: 1.7;
    color: var(--text-2);
}

.feature-list {
    padding-left: 18px;
}

.toast-host {
    position: fixed;
    left: 50%;
    bottom: 28px;
    transform: translateX(-50%);
    z-index: 30;
    display: flex;
    flex-direction: column;
    gap: 8px;
    pointer-events: none;
}

.toast {
    padding: 10px 16px;
    border-radius: 8px;
    background: rgba(29, 33, 41, 0.9);
    color: #fff;
    font-size: 14px;
    box-shadow: 0 6px 16px rgba(0, 0, 0, 0.12);
    animation: toast-in var(--slow) var(--ease-out) both;
}

.toast.is-out {
    animation: toast-out var(--mid) var(--ease) both;
}

@keyframes toast-in {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes toast-out {
    from { opacity: 1; transform: translateY(0); }
    to { opacity: 0; transform: translateY(12px); }
}

body.theme-dark {
    --text: #f2f3f5;
    --text-2: #c9cdd4;
    --text-3: #86909c;
    --line: #33363d;
    --fill: #2a2c31;
    --sidebar: #17181a;
    --page: #101114;
}

body.theme-dark .chat-header,
body.theme-dark .info-sidebar,
body.theme-dark .form-group input,
body.theme-dark .form-group textarea,
body.theme-dark .form-group select,
body.theme-dark .chat-input-wrapper,
body.theme-dark .theme-dropdown {
    background: #1c1e22;
    color: var(--text);
}

body.theme-dark .chat-input-container {
    background: linear-gradient(to top, #101114 72%, rgba(16, 17, 20, 0));
}

body.theme-dark .chat-input,
body.theme-dark .btn-primary {
    color: var(--text);
}

body.theme-dark .btn-send.is-idle:not(.is-busy),
body.theme-dark .btn-send.is-idle:not(.is-busy):hover {
    background: #3a3d44;
    color: #86909c;
}

body.theme-dark .jump-bottom,
body.theme-dark .starter-chip {
    background: #1c1e22;
    color: var(--text-2);
    border-color: var(--line);
}

body.theme-dark .jump-bottom:hover,
body.theme-dark .starter-chip:hover {
    background: #2a2c31;
    color: var(--text);
}

body.theme-dark .btn-primary:hover,
body.theme-dark .session-btn:hover,
body.theme-dark .btn-ghost:hover,
body.theme-dark .btn-theme:hover,
body.theme-dark .theme-option:hover,
body.theme-dark .theme-option.active {
    background: #2a2c31;
}

body.theme-dark .session-btn.btn-active {
    background: #2e3138;
}

body.theme-dark .message-avatar {
    background: #1d2a44;
}

body.theme-dark .message.user .message-content {
    color: var(--text);
}

body.theme-dark .info-sidebar {
    border-left-color: var(--line);
}

body.theme-dark .form-group select option {
    background: #1c1e22;
}

body.theme-dark .toast {
    background: #f2f3f5;
    color: #1d2129;
}

body.theme-dark .chat-messages::-webkit-scrollbar-thumb,
body.theme-dark .sidebar::-webkit-scrollbar-thumb {
    background: #3a3d44;
}

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation: none !important;
        transition: none !important;
    }
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -260px;
        top: 0;
        height: 100vh;
        z-index: 15;
        transition: left var(--slow) var(--ease-drawer), background-color var(--slow) var(--ease);
    }

    .sidebar.open {
        left: 0;
    }

    .chat-body,
    .chat-input-wrapper {
        width: calc(100% - 32px);
    }
}