:root {
    --color-primary: #3498db;
    --color-primary-hover: #2980b9;
    --color-secondary: #2c3e50;
    --color-accent: #e74c3c;
    --color-success: #27ae60;
    --color-text: #333;
    --color-text-secondary: #7f8c8d;
    --color-bg: #f8f9fa;
    --color-card-bg: #ffffff;
    --color-border: #e0e0e0;
    --color-shadow: rgba(0, 0, 0, 0.1);
    --color-overlay: rgba(0, 0, 0, 0.85);
    --font-main: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    --border-radius: 8px;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --max-width: 800px;
}

[data-theme="dark"] {
    --color-primary: #41a3ff;
    --color-primary-hover: #3a96e6;
    --color-secondary: #1f2b38;
    --color-text: #e0e0e0;
    --color-text-secondary: #b0b0b0;
    --color-bg: #1f2b38;
    --color-card-bg: #2a3849;
    --color-border: #1f2b38;
    --color-shadow: rgba(0, 0, 0, 0.3);
    --color-overlay: rgba(0, 0, 0, 0.95);
}

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

html {
    font-size: 16px;
}

body {
    font-family: var(--font-main);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* --- 布局 --- */
.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.app-header {
    background-color: var(--color-secondary);
    color: white;
    padding: var(--spacing-md) var(--spacing-sm);
    text-align: center;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    flex-shrink: 0;
}

.app-title {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.app-main {
    flex: 1;
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: var(--spacing-lg) var(--spacing-sm);
    width: 100%;
}

.app-footer {
    text-align: center;
    padding: var(--spacing-md) var(--spacing-sm);
    color: var(--color-text-secondary);
    font-size: 0.9rem;
    flex-shrink: 0;
}
footer a {
    color: var(--color-text-secondary);
    text-decoration: none;
}
footer a:hover {
    text-decoration: underline;
}

/* --- 链接样式 --- */
.contact-link {
    color: #3caffc;
    text-decoration: underline;
}

/* --- 下载区域 --- */
.download-section {
    width: 100%;
}

.section-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--color-primary);
}

.section-description {
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-lg);
}

/* --- 下载卡片 --- */
.download-card {
    background-color: var(--color-card-bg);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 12px var(--color-shadow);
    overflow: hidden;
    margin-bottom: var(--spacing-md);
    transition: var(--transition);
}

.download-card:hover {
    box-shadow: 0 6px 16px var(--color-shadow);
    transform: translateY(-2px);
}

.card-header {
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--color-primary);
}

.card-description {
    color: var(--color-text-secondary);
    font-size: 0.95rem;
    margin: 0;
}

.card-actions {
    padding: var(--spacing-md);
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.card-content {
    padding: var(--spacing-md);
}

/* --- 按钮 --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    font-size: 1rem;
    text-decoration: none;
    cursor: pointer;
    border: none;
    transition: var(--transition);
    flex: 1 1 auto;
    min-width: 120px;
    text-align: center;
    gap: 0.5rem; /* 图标与文字间距 */
}

.btn-primary {
    background-color: var(--color-primary);
    color: white;
}

.btn-primary:hover:not(:disabled) {
    background-color: var(--color-primary-hover);
    transform: translateY(-2px);
}

.btn-secondary {
    background-color: var(--color-primary);
    color: white;
}

.btn-secondary:hover:not(:disabled) {
    background-color: var(--color-primary-hover);
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-primary);
}

.btn-outline:hover:not(:disabled) {
    background-color: var(--color-primary);
    color: white;
    transform: translateY(-2px);
}

.btn:disabled,
.btn.disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none !important;
    box-shadow: none !important;
}

/* --- 输入框组 --- */
.input-group {
    margin-bottom: var(--spacing-md);
}

.input-label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
    color: var(--color-text);
}

.input-wrapper {
    display: flex;
}

.input-field {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    background-color: var(--color-card-bg);
    color: var(--color-text);
    font-size: 1rem;
    min-width: 0; /* 防止 flex 溢出 */
}

.input-field:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}

.btn-icon {
    background-color: var(--color-primary);
    color: white;
    border: 1px solid var(--color-primary);
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    padding: 0 1rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-icon:hover {
    background-color: var(--color-primary-hover);
}

/* --- 消息提示 (Toast) --- */
.toast {
    position: fixed;
    top: var(--spacing-md);
    left: 50%;
    transform: translateX(-50%) translateY(-100px);
    background-color: var(--color-primary);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--border-radius);
    box-shadow: 0 4px 12px var(--color-shadow);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 1000;
    font-weight: 500;
}

.toast.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.toast.success {
    background-color: var(--color-success);
}

.toast.error {
    background-color: var(--color-accent);
}

/* --- 遮罩层 --- */
#download-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--color-overlay);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
    cursor: pointer;
    padding: var(--spacing-md);
    text-align: center;
}

#download-overlay.show {
    opacity: 1;
    visibility: visible;
}

#download-overlay .overlay-main {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: var(--spacing-sm);
    color: #ffffff;
}

#download-overlay .overlay-normal {
    font-size: 1rem;
    margin-bottom: var(--spacing-md);
    color: #f0f0f0;
    max-width: 600px;
    line-height: 1.7;
}

#download-overlay .overlay-small {
    font-size: 0.875rem;
    color: #d0d0d0;
}

/* --- 响应式 --- */
@media (max-width: 768px) {
    .app-main {
        padding: var(--spacing-md) var(--spacing-sm);
    }

    .card-actions {
        flex-direction: column;
        padding: var(--spacing-sm);
    }

    .card-content {
        padding: var(--spacing-sm);
    }

    .btn {
        width: 100%;
        padding: 0.8rem;
    }

    .input-wrapper {
        flex-direction: column;
    }

    .input-field {
        border-radius: var(--border-radius) var(--border-radius) 0 0;
        border-bottom: none;
    }

    .btn-icon {
        border-radius: 0 0 var(--border-radius) var(--border-radius);
        border-top: none;
        padding: 0.8rem;
    }

    #download-overlay .overlay-main {
        font-size: 1.2rem;
    }

    #download-overlay .overlay-normal {
        font-size: 0.9rem;
    }
}

@media (max-width: 480px) {

    .btn {
        padding: 0.7rem;
        font-size: 0.95rem;
    }
}