/* ===== CSS Custom Properties - Theme System ===== */

:root {
    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    --space-3xl: 64px;

    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    --font-mono: "SF Mono", "Fira Code", "Consolas", "Menlo", monospace;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-weight-normal: 400;
    --font-weight-medium: 500;
    --font-weight-semibold: 600;
    --font-weight-bold: 700;
    --line-height-tight: 1.25;
    --line-height-normal: 1.6;
    --line-height-relaxed: 1.8;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.08);
    --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.1);

    /* Glass */
    --glass-blur: blur(16px);
    --glass-saturate: 180%;
}

/* ===== Light Theme (Default) ===== */
[data-theme="light"] {
    --color-bg-primary: #ffffff;
    --color-bg-secondary: #f5f5f7;
    --color-bg-tertiary: #ebebed;
    --color-bg-elevated: rgba(255, 255, 255, 0.72);
    --color-bg-glass: rgba(255, 255, 255, 0.64);
    --color-bg-hover: rgba(0, 0, 0, 0.04);
    --color-bg-active: rgba(0, 0, 0, 0.06);
    --color-bg-card: #ffffff;
    --color-bg-input: rgba(0, 0, 0, 0.04);
    --color-bg-overlay: rgba(0, 0, 0, 0.32);
    --color-bg-highlight: rgba(0, 0, 0, 0.06);

    --color-text-primary: #1a1a1c;
    --color-text-secondary: #5a5a5e;
    --color-text-tertiary: #8a8a8e;
    --color-text-placeholder: #b0b0b4;
    --color-text-inverse: #ffffff;

    --color-border-primary: rgba(0, 0, 0, 0.08);
    --color-border-secondary: rgba(0, 0, 0, 0.05);
    --color-border-hover: rgba(0, 0, 0, 0.14);
    --color-border-active: rgba(0, 0, 0, 0.24);

    --color-accent-primary: #1a1a1c;
    --color-accent-secondary: #3a3a3e;
    --color-accent-hover: #000000;
    --color-accent-muted: rgba(0, 0, 0, 0.06);

    --color-tag-bg: rgba(0, 0, 0, 0.05);
    --color-tag-text: #3a3a3e;
    --color-tag-hover: rgba(0, 0, 0, 0.1);

    --color-star: #3a3a3e;
    --color-star-empty: #d0d0d4;

    --color-glass-border: rgba(0, 0, 0, 0.06);
    --color-glass-shadow: rgba(0, 0, 0, 0.04);

    --color-scrollbar-thumb: rgba(0, 0, 0, 0.16);
    --color-scrollbar-track: transparent;

    --gradient-accent: linear-gradient(135deg, #1a1a1c 0%, #3a3a3e 100%);
    --gradient-subtle: linear-gradient(180deg, rgba(0,0,0,0.01) 0%, rgba(0,0,0,0.02) 100%);
}

/* ===== Dark Theme ===== */
[data-theme="dark"] {
    --color-bg-primary: #0d0d0f;
    --color-bg-secondary: #141417;
    --color-bg-tertiary: #1c1c20;
    --color-bg-elevated: rgba(20, 20, 23, 0.8);
    --color-bg-glass: rgba(24, 24, 28, 0.7);
    --color-bg-hover: rgba(255, 255, 255, 0.04);
    --color-bg-active: rgba(255, 255, 255, 0.06);
    --color-bg-card: #1a1a1e;
    --color-bg-input: rgba(255, 255, 255, 0.04);
    --color-bg-overlay: rgba(0, 0, 0, 0.6);
    --color-bg-highlight: rgba(255, 255, 255, 0.06);

    --color-text-primary: #e8e8ec;
    --color-text-secondary: #a0a0a8;
    --color-text-tertiary: #686870;
    --color-text-placeholder: #505058;
    --color-text-inverse: #0d0d0f;

    --color-border-primary: rgba(255, 255, 255, 0.08);
    --color-border-secondary: rgba(255, 255, 255, 0.05);
    --color-border-hover: rgba(255, 255, 255, 0.14);
    --color-border-active: rgba(255, 255, 255, 0.24);

    --color-accent-primary: #e8e8ec;
    --color-accent-secondary: #c0c0c8;
    --color-accent-hover: #ffffff;
    --color-accent-muted: rgba(255, 255, 255, 0.06);

    --color-tag-bg: rgba(255, 255, 255, 0.06);
    --color-tag-text: #b0b0b8;
    --color-tag-hover: rgba(255, 255, 255, 0.12);

    --color-star: #a0a0a8;
    --color-star-empty: #3a3a3e;

    --color-glass-border: rgba(255, 255, 255, 0.06);
    --color-glass-shadow: rgba(0, 0, 0, 0.16);

    --color-scrollbar-thumb: rgba(255, 255, 255, 0.16);
    --color-scrollbar-track: transparent;

    --gradient-accent: linear-gradient(135deg, #e8e8ec 0%, #c0c0c8 100%);
    --gradient-subtle: linear-gradient(180deg, rgba(255,255,255,0.02) 0%, rgba(255,255,255,0.01) 100%);
}

/* ===== System Preference Auto-Detection ===== */
@media (prefers-color-scheme: dark) {
    html:not([data-theme]) {
        --color-bg-primary: #0d0d0f;
        --color-bg-secondary: #141417;
        --color-bg-tertiary: #1c1c20;
        --color-bg-elevated: rgba(20, 20, 23, 0.8);
        --color-bg-glass: rgba(24, 24, 28, 0.7);
        --color-bg-hover: rgba(255, 255, 255, 0.04);
        --color-bg-active: rgba(255, 255, 255, 0.06);
        --color-bg-card: #1a1a1e;
        --color-bg-input: rgba(255, 255, 255, 0.04);
        --color-bg-overlay: rgba(0, 0, 0, 0.6);
        --color-bg-highlight: rgba(255, 255, 255, 0.06);

        --color-text-primary: #e8e8ec;
        --color-text-secondary: #a0a0a8;
        --color-text-tertiary: #686870;
        --color-text-placeholder: #505058;
        --color-text-inverse: #0d0d0f;

        --color-border-primary: rgba(255, 255, 255, 0.08);
        --color-border-secondary: rgba(255, 255, 255, 0.05);
        --color-border-hover: rgba(255, 255, 255, 0.14);
        --color-border-active: rgba(255, 255, 255, 0.24);

        --color-accent-primary: #e8e8ec;
        --color-accent-secondary: #c0c0c8;
        --color-accent-hover: #ffffff;
        --color-accent-muted: rgba(255, 255, 255, 0.06);

        --color-tag-bg: rgba(255, 255, 255, 0.06);
        --color-tag-text: #b0b0b8;
        --color-tag-hover: rgba(255, 255, 255, 0.12);

        --color-star: #a0a0a8;
        --color-star-empty: #3a3a3e;

        --color-glass-border: rgba(255, 255, 255, 0.06);
        --color-glass-shadow: rgba(0, 0, 0, 0.16);

        --color-scrollbar-thumb: rgba(255, 255, 255, 0.16);
        --color-scrollbar-track: transparent;

        --gradient-accent: linear-gradient(135deg, #e8e8ec 0%, #c0c0c8 100%);
        --gradient-subtle: linear-gradient(180deg, rgba(255,255,255,0.02) 0%, rgba(255,255,255,0.01) 100%);
    }
}

/* ===== Theme Transition ===== */
html.theme-transition,
html.theme-transition *,
html.theme-transition *::before,
html.theme-transition *::after {
    transition: background-color var(--transition-normal),
                color var(--transition-normal),
                border-color var(--transition-normal),
                box-shadow var(--transition-normal),
                opacity var(--transition-normal) !important;
}

/* ===== Base Reset ===== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    text-rendering: optimizeLegibility;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--font-size-base);
    line-height: var(--line-height-normal);
    color: var(--color-text-primary);
    background-color: var(--color-bg-primary);
    transition: background-color var(--transition-normal), color var(--transition-normal);
    min-height: 100vh;
    overflow-x: hidden;
}

a {
    color: inherit;
    text-decoration: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
    color: inherit;
    font-size: inherit;
}

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

ul, ol {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

/* ===== Scrollbar ===== */
::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}
::-webkit-scrollbar-track {
    background: var(--color-scrollbar-track);
}
::-webkit-scrollbar-thumb {
    background: var(--color-scrollbar-thumb);
    border-radius: var(--radius-full);
}
::-webkit-scrollbar-thumb:hover {
    background: var(--color-text-tertiary);
}

/* ===== Utility: Glass Effect ===== */
.glass {
    background: var(--color-bg-glass);
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    border: 1px solid var(--color-glass-border);
}