:root {
    --primary: #2563eb;
    --sidebar-bg: #ffffff;
    --main-bg: #fcfdfe;
    --outer-bg: #f3f4f6;
    --text-main: #1e293b;
    --text-muted: #94a3b8;
    --ease-out-expo: cubic-bezier(0.19, 1, 0.22, 1);
}

/* --- 基础复位 --- */
* { 
    margin: 0; 
    padding: 0; 
    box-sizing: border-box; 
    -webkit-font-smoothing: antialiased; 
    -moz-osx-font-smoothing: grayscale;
}

body, html {
    width: 100%;
    height: 100%;
    background-color: var(--outer-bg);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", sans-serif;
    overflow: hidden; /* 禁止溢出滚动，保持单屏大气感 */
}

/* --- 1. 高端全屏载入动画 (Preloader) --- */
#preloader {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #0a0a0a; /* 极夜黑，营造高级感 */
    z-index: 9999;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transition: transform 1s var(--ease-out-expo);
}

/* 载入时的品牌名称 */
.loader-brand {
    color: #ffffff;
    font-size: 2.5rem;
    font-weight: 900;
    letter-spacing: -1.5px;
    margin-bottom: 20px;
    opacity: 0;
    transform: translateY(20px);
    animation: loaderTextIn 0.8s forwards 0.2s;
}

/* 极简进度条 */
.loader-bar {
    width: 240px;
    height: 1px;
    background: rgba(255,255,255,0.1);
    position: relative;
    overflow: hidden;
}

.loader-bar::after {
    content: '';
    position: absolute;
    left: -100%;
    top: 0;
    width: 100%;
    height: 100%;
    background: var(--primary);
    animation: lineProgress 1.2s var(--ease-out-expo) forwards 0.4s;
}

@keyframes loaderTextIn {
    to { opacity: 1; transform: translateY(0); }
}

@keyframes lineProgress {
    to { left: 0; }
}

/* 载入完成后：幕布向上滑动揭幕 */
body.loaded #preloader {
    transform: translateY(-100%);
}

/* --- 2. 页面主布局 --- */
.full-screen-layout {
    display: flex;
    width: 100vw;
    height: 100vh;
    align-items: center;
    padding: 0 4vw; /* 外部留白保持呼吸感 */
    gap: 3vw;
    position: relative;
}

/* 入场动画基类 */
.animate-up {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 1.5s var(--ease-out-expo), transform 1.5s var(--ease-out-expo);
}

body.loaded .animate-up {
    opacity: 1;
    transform: translateY(0);
}

/* --- 3. 左侧文案区 (占比 30%) --- */
.hero-area {
    flex: 0 0 30%;
    z-index: 5;
}

.brand-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 2.5vh;
    transition-delay: 0.7s;
}

.brand-logo svg {
    width: 54px;
    height: 54px;
    fill: var(--primary);
}

.brand-name {
    font-size: 3.8rem;
    font-weight: 900;
    letter-spacing: -3px;
    color: #000000;
}

.hero-title {
    font-size: 3.2rem;
    font-weight: 800;
    color: #0f172a;
    line-height: 1.2;
    margin-bottom: 2vh;
    transition-delay: 0.8s;
}

.hero-tagline {
    font-size: 1.5rem;
    color: #64748b;
    margin-bottom: 7vh;
    transition-delay: 0.9s;
    font-weight: 400;
}

/* 特色小卡片网格 */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5vw;
}

.feat-item { transition-delay: 1.0s; }
.feat-item:nth-child(2) { transition-delay: 1.1s; }
.feat-item:nth-child(3) { transition-delay: 1.2s; }

.feat-icon-box {
    width: 54px;
    height: 54px;
    background: #ffffff;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 8px 20px rgba(0,0,0,0.04);
    margin-bottom: 15px;
    fill: var(--primary);
    transition: transform 0.3s ease;
}

.feat-item:hover .feat-icon-box {
    transform: translateY(-5px);
    background: #eff6ff;
}

.feat-item h3 {
    font-size: 1.15rem;
    font-weight: 700;
    color: #1e293b;
    margin-bottom: 8px;
}

.feat-item p {
    font-size: 0.9rem;
    color: #94a3b8;
    line-height: 1.5;
}

/* --- 4. 右侧 Mockup 区域 (占比 70%) --- */
.mockup-area {
    flex: 1;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    position: relative;
    transition-delay: 1.3s;
}

/* 右上角固定的操作按钮 */
.top-nav {
    position: absolute;
    top: 2vh;
    right: 0;
    display: flex;
    gap: 16px;
    z-index: 100;
    transition-delay: 1.5s;
}

.btn-secondary {
    padding: 12px 36px;
    border: 1.5px solid #e2e8f0;
    background: #ffffff;
    border-radius: 12px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-secondary:hover {
    border-color: #cbd5e1;
    background: #f8fafc;
}

.btn-primary {
    padding: 12px 36px;
    background: var(--primary);
    color: #ffffff;
    border: none;
    border-radius: 12px;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    box-shadow: 0 10px 25px rgba(37, 99, 235, 0.25);
    transition: all 0.3s;
}

.btn-primary:hover {
    transform: translateY(-2px);
    background: #1d4ed8;
    box-shadow: 0 15px 30px rgba(37, 99, 235, 0.35);
}

/* 3D 浮动动效容器 */
.floating-container {
    width: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    animation: floatLarge 8s ease-in-out infinite;
    perspective: 2000px;
}

@keyframes floatLarge {
    0%, 100% { transform: translateY(0) rotateX(0); }
    50% { transform: translateY(-20px) rotateX(1deg); }
}

/* 笔记本外框（还原图中的深色边框） */
.laptop-frame {
    width: 100%;
    background: #ffffff;
    border: 14px solid #1e293b;
    border-radius: 28px 28px 0 0;
    box-shadow: 0 80px 150px -40px rgba(0,0,0,0.25);
    overflow: hidden;
}

/* --- 5. 内部软件 UI 像素级还原 --- */
.app-shell {
    height: 72vh; /* 撑满屏幕比例 */
    display: flex;
    background: var(--main-bg);
}

/* 侧边栏 */
.sidebar {
    width: 250px;
    background: #ffffff;
    border-right: 1px solid #f1f5f9;
    padding: 40px 24px;
    display: flex;
    flex-direction: column;
}

.sidebar-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 900;
    font-size: 1.1rem;
    color: #000000;
    margin-bottom: 40px;
}

.search-input {
    width: 100%;
    background: #f3f4f6;
    border-radius: 12px;
    padding: 14px 18px;
    font-size: 13px;
    color: #94a3b8;
    margin-bottom: 30px;
    border: none;
}

.menu-item {
    padding: 14px 18px;
    border-radius: 12px;
    font-size: 14px;
    color: #64748b;
    margin-bottom: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    cursor: pointer;
    transition: all 0.2s;
}

.menu-item.active {
    background: var(--primary);
    color: #ffffff;
    font-weight: 600;
}

.menu-item:not(.active):hover {
    background: #f8fafc;
    color: #1e293b;
}

/* 主体内容区 */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.top-user-bar {
    height: 70px;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    padding: 0 40px;
    gap: 15px;
}

.avatar {
    width: 32px;
    height: 32px;
    background: var(--primary);
    border-radius: 50%;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: 700;
}

.user-name {
    font-size: 13px;
    font-weight: 700;
    color: #334155;
}

.content-body {
    padding: 40px 50px;
    flex: 1;
}

.body-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 40px;
}

.body-header h2 {
    font-size: 30px;
    font-weight: 850;
    color: #0f172a;
}

.btn-add-note {
    background: var(--primary);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 12px;
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
    transition: transform 0.2s;
}

.btn-add-note:hover {
    transform: scale(1.02);
}

/* 笔记卡片 */
.note-card {
    width: 420px;
    background: #ffffff;
    border: 1px solid #f1f5f9;
    border-radius: 20px;
    padding: 35px;
    box-shadow: 0 10px 40px rgba(0,0,0,0.03);
    transition: all 0.3s;
}

.note-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 50px rgba(0,0,0,0.06);
}

.card-category {
    display: inline-block;
    background: #f8fafc;
    color: #94a3b8;
    font-size: 12px;
    font-weight: 600;
    padding: 6px 16px;
    border-radius: 10px;
    margin-bottom: 20px;
}

.note-card h4 {
    font-size: 20px;
    font-weight: 800;
    color: #1e293b;
    margin-bottom: 12px;
}

.note-card p {
    font-size: 15px;
    color: #94a3b8;
    line-height: 1.8;
}

/* 底部操作条 */
.app-footer {
    height: 90px;
    border-top: 1px solid #f1f5f9;
    background: #ffffff;
    padding: 0 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.selection-status {
    font-size: 14px;
    color: #cbd5e1;
    font-style: italic;
}

.footer-btns {
    display: flex;
    gap: 15px;
}

.btn-footer-gray {
    padding: 12px 24px;
    background: #ffffff;
    border: 1.5px solid #f1f5f9;
    color: #94a3b8;
    border-radius: 10px;
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
}

.btn-footer-blue {
    padding: 12px 24px;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: 10px;
    font-weight: 600;
    font-size: 13px;
    cursor: pointer;
}

/* 笔记本底座 */
.laptop-bottom {
    width: 104%;
    height: 24px;
    background: linear-gradient(to bottom, #d1d5db, #9ca3af);
    margin-left: -2%;
    border-radius: 0 0 28px 28px;
    position: relative;
}

.laptop-bottom::after {
    content: "";
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 160px;
    height: 8px;
    background: rgba(0,0,0,0.1);
    border-radius: 0 0 15px 15px;
}