/* --- 1a. 主题与变量定义 (Theme & Variables) --- */
:root {
    --font-family: 'Rubik', 'Noto Sans SC', sans-serif;

    --primary-color: #6750A4; /* 主色 - 柔和紫 */
    --on-primary: #FFFFFF;
    --primary-container: #EADDFF;
    --on-primary-container: #21005D;
    
    --secondary-color: #006A60; /* 强调色 - 活力绿 */
    --on-secondary: #FFFFFF;
    
    --surface-container-highest: #E6E0E9; /* 卡片背景 */
    --surface-container-low: #F7F2FA;
    --on-surface: #1C1B1F; /* 主要文字颜色 */
    --on-surface-variant: #49454F; /* 次要文字颜色 */
    
    --background: #FFFBFE; /* 页面背景 */
    --outline: #79747E;
    
    /* Shape & Motion Tokens */
    --radius-l: 24px;
    --radius-m: 16px;
    --motion-duration: 0.5s;
    --motion-easing: cubic-bezier(0.2, 0.8, 0.2, 1);
}


/* --- 1b. 黑夜模式主题定义 (Dark Theme Definition) --- */
[data-theme="dark"] {
    /* Material 3 Dark Palette */
    --primary-color: #D0BCFF; /* 主色 - 柔和紫 */
    --on-primary: #381E72;
    --primary-container: #4F378B;
    --on-primary-container: #EADDFF;
    
    --secondary-color: #4DDABF; /* 强调色 - 活力绿 */
    --on-secondary: #003731;
    
    --surface-container-highest: #36343B; /* 卡片背景 */
    --surface-container-low: #1C1B1F;
    --on-surface: #E6E1E5; /* 主要文字颜色 */
    --on-surface-variant: #CAC4D0; /* 次要文字颜色 */
    
    --background: #141218; /* 页面背景 */
    --outline: #938F99;
}

/* --- 2. 全局样式与重置 (Global Styles & Reset) --- */
*, *::before, *::after {
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background-color: var(--background);
    color: var(--on-surface);
    margin: 0;
    padding: 20px;
}

.main-container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
}

/* --- 3. 入场动效 (Entrance Animation) --- */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.animate-in {
    animation: fadeInUp var(--motion-duration) var(--motion-easing) both;
    animation-delay: var(--delay, 0s);
}


/* --- 4. 页面元素样式 (Page Elements) --- */
.hero-header {
    text-align: center;
    padding: 20px 0 40px 0;
}
.hero-header h1 {
    font-size: clamp(2rem, 5vw, 3rem); /* 响应式字体 */
    font-weight: 700;
    margin: 0 0 10px 0;
}
.hero-header p {
    font-size: 1.1rem;
    color: var(--on-surface-variant);
    margin: 0;
}

.card {
    background: var(--surface-container-low);
    border-radius: var(--radius-l);
    padding: 30px;
    margin-bottom: 30px;
    border: 1px solid var(--surface-container-highest);
}

/* 上传区域 */
.upload-card form {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.file-drop-zone {
    width: 100%;
    background: var(--background);
    border: 2px dashed var(--outline);
    border-radius: var(--radius-m);
    padding: 40px 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s var(--motion-easing);
}
.file-drop-zone:hover {
    border-color: var(--primary-color);
    transform: scale(1.02);
    background: var(--primary-container);
}
/* 当文件被拖拽到区域上空时的样式 */
.file-drop-zone.is-dragging {
    border-style: solid; 
    border-color: var(--primary-color);
    background-color: var(--primary-container);
    transform: scale(1.03); 
    box-shadow: 0 0 20px rgba(103, 80, 164, 0.2); 
}
.file-drop-zone .icon-upload {
    color: var(--primary-color);
    margin-bottom: 15px;
    transition: transform 0.3s var(--motion-easing);
}
.file-drop-zone:hover .icon-upload {
    transform: translateY(-5px);
}
.file-drop-zone span {
    font-weight: 500;
    color: var(--on-surface-variant);
}
#file-name-display {
    margin-top: 15px;
    font-size: 0.9rem;
    color: var(--primary-color);
    font-weight: 500;
    display: none;
}

.submit-button {
    background-color: var(--primary-color);
    color: var(--on-primary);
    border: none;
    font-size: 1.1rem;
    font-weight: 500;
    padding: 16px 40px;
    border-radius: 50px; /* 胶囊形状 */
    cursor: pointer;
    margin-top: 25px;
    transition: all 0.3s var(--motion-easing);
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}
.submit-button:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(103, 80, 164, 0.3);
}
.submit-button:active {
    transform: translateY(-1px);
    box-shadow: 0 4px 15px rgba(103, 80, 164, 0.2);
}

/* 结果区域 */
.results-container {
    display: grid;
    grid-template-columns: 1fr; /* 移动端默认单列 */
    gap: 30px;
}

.card h2 {
    margin-top: 0;
    margin-bottom: 25px;
    font-weight: 500;
    color: var(--on-surface-variant);
}

.image-wrapper {
    overflow: hidden;
    border-radius: var(--radius-m);
}
.image-wrapper img {
    display: block;
    width: 100%;
    height: auto;
}

.suggestion-box, .possibilities-box {
    margin-bottom: 30px;
}

.suggestion-label {
    display: block;
    font-size: 0.9rem;
    color: var(--on-surface-variant);
    margin-bottom: 8px;
}

.hero-suggestion {
    font-size: clamp(1rem, 4vw, 1.8rem);
    font-weight: 500;
    margin: 0;
    text-align: center;
    padding: 20px;
    border-radius: var(--radius-m);
    background: linear-gradient(120deg, var(--primary-container), var(--surface-container-highest));
    color: var(--on-primary-container);
}

.word-chip-container {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}
.word-chip {
    background-color: var(--surface-container-highest);
    padding: 8px 18px;
    border-radius: 50px;
    font-family: monospace;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--on-surface-variant);
    transition: all 0.2s ease;
}
.word-chip:hover {
    transform: scale(1.05);
    background-color: var(--primary-container);
    color: var(--on-primary-container);
}

/* --- 开关样式 (Theme Switch Styles) - v2 --- */
.hero-header {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 20px; 
}

.theme-switch-wrapper {
    display: flex;
    align-items: center;
}

/* 1. 总容器 (label.theme-switch) */
.theme-switch {
    position: relative;
    display: block; 
    width: 60px;
    height: 34px;
    cursor: pointer;
    transition: none; 
}

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

/* 2. 背景轨道 (.slider-track) */
.slider-track {
    position: absolute;
    top: 0;
    left: 0;
    width: 34px; /* 默认是收缩的圆形 */
    height: 34px;
    background-color: var(--surface-container-highest);
    border-radius: 17px; /* 圆形 */
    box-shadow: inset 2px 2px 4px rgba(0,0,0,0.2), 
                    inset -2px -2px 4px rgba(255,255,255,0.05);
    transition: width 0.3s ease, left 0.3s ease, border-radius 0.3s ease;
}

/* 鼠标悬停时，轨道展开 */
.theme-switch:hover .slider-track {
    width: 60px; /* 展开为长条形 */
}

/* 当开关被选中(夜间模式)且鼠标未悬停时，轨道移动到右边 */
.theme-switch input:checked + .slider-track {
    left: 26px; /* 60px - 34px = 26px，移动到最右侧 */
}
/* 鼠标悬停在已选中的开关上时，轨道也要保持在左侧展开 */
.theme-switch:hover input:checked + .slider-track {
    left: 0;
}


/* 3. 滑块圆点 (.slider-dot) */
.slider-dot {
    position: absolute;
    height: 26px;
    width: 26px;
    left: 4px;
    top: 4px;
    background-color: var(--primary-color);
    border-radius: 50%;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    /* 核心动画：只负责平移和颜色变化 */
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), background-color 0.3s ease;
}

/* 当开关被选中(夜间模式)时，圆点向右移动 */
.theme-switch input:checked ~ .slider-dot {
    transform: translateX(26px);
    background-color: var(--primary-container);
}


/* 4. 图标样式 */
.slider-dot .icon {
    position: absolute;
    width: 20px;
    height: 20px;
    color: var(--on-primary);
    transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    display: flex;
    align-items: center;      /* 垂直居中 */
    justify-content: center;  

}

.sun {
    opacity: 1;
    transform: translateY(0) rotate(0deg);
}
.moon {
    opacity: 0;
    transform: translateY(20px) rotate(-45deg); /* 从下方进入 */
}

input:checked ~ .slider-dot .sun {
    opacity: 0;
    transform: translateY(-20px) rotate(45deg); /* 向上方退出 */
}
input:checked ~ .slider-dot .moon {
    opacity: 1;
    transform: translateY(0) rotate(0deg);
    color: var(--on-primary-container);
}

/* --- 5. 响应式布局 (Responsive Layout) --- */
@media (min-width: 900px) {
    .results-container {
        /* 在大屏幕上变为两栏，结果栏更宽 */
        grid-template-columns: 1fr 1.5fr; 
    }
}