/* ==========================================================================
   Discuz X5 Modern Theme - Base Design System
   Modern minimalist design inspired by Flarum/NodeBB
   ========================================================================== */

/* ----------------------------------------
   CSS Custom Properties - Light Mode (Default)
   ---------------------------------------- */
:root {
    --modern-primary: #4f6ef7;
    --modern-primary-hover: #3d5bd9;
    --modern-primary-light: #eef1ff;
    --modern-primary-dark: #3451c7;
    --modern-surface: #ffffff;
    --modern-surface-secondary: #f8f9fa;
    --modern-surface-tertiary: #f0f2f5;
    --modern-surface-hover: #f2f4f7;
    --modern-text-primary: #1a1d26;
    --modern-text-secondary: #5f6b7a;
    --modern-text-tertiary: #8b95a5;
    --modern-text-quaternary: #b0b8c4;
    --modern-text-link: #4f6ef7;
    --modern-text-on-primary: #ffffff;
    --modern-border: #e2e5eb;
    --modern-border-light: #edf0f4;
    --modern-border-hover: #cdd3de;
    --modern-success: #22c55e;
    --modern-success-light: #dcfce7;
    --modern-warning: #f59e0b;
    --modern-warning-light: #fef3c7;
    --modern-danger: #ef4444;
    --modern-danger-light: #fee2e2;
    --modern-info: #3b82f6;
    --modern-info-light: #dbeafe;
    --modern-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --modern-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --modern-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.05);
    --modern-shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.05);
    --modern-radius-sm: 6px;
    --modern-radius-md: 10px;
    --modern-radius-lg: 14px;
    --modern-radius-xl: 18px;
    --modern-radius-full: 9999px;
    --modern-radius-avatar: 50%;
    --modern-space-1: 4px;
    --modern-space-2: 8px;
    --modern-space-3: 12px;
    --modern-space-4: 16px;
    --modern-space-5: 20px;
    --modern-space-6: 24px;
    --modern-space-8: 32px;
    --modern-space-10: 40px;
    --modern-space-12: 48px;
    --modern-space-16: 64px;
    --modern-font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Microsoft YaHei", sans-serif;
    --modern-font-mono: "SF Mono", "Fira Code", "Fira Mono", "Roboto Mono", Consolas, monospace;
    --modern-font-size-xs: 0.75rem;
    --modern-font-size-sm: 0.8125rem;
    --modern-font-size-base: 0.9375rem;
    --modern-font-size-md: 1rem;
    --modern-font-size-lg: 1.125rem;
    --modern-font-size-xl: 1.25rem;
    --modern-font-size-2xl: 1.5rem;
    --modern-font-size-3xl: 1.875rem;
    --modern-line-height: 1.6;
    --modern-line-height-tight: 1.3;
    --modern-line-height-relaxed: 1.75;
    --modern-transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --modern-transition-base: 200ms cubic-bezier(0.4, 0, 0.2, 1);
    --modern-transition-slow: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --modern-header-height: 60px;
    --modern-sidebar-width: 260px;
    --modern-content-max-width: 1200px;
    --modern-content-width: 1000px;
    --modern-z-dropdown: 100;
    --modern-z-sticky: 200;
    --modern-z-fixed: 300;
    --modern-z-modal-backdrop: 400;
    --modern-z-modal: 500;
    --modern-z-popover: 600;
    --modern-z-tooltip: 700;
}

/* Dark Mode */
.modern-dark-mode {
    --modern-primary: #6b8aff;
    --modern-primary-hover: #8ba5ff;
    --modern-primary-light: #1e2545;
    --modern-primary-dark: #4f6ef7;
    --modern-surface: #1a1d26;
    --modern-surface-secondary: #22252f;
    --modern-surface-tertiary: #292d38;
    --modern-surface-hover: #2d313d;
    --modern-text-primary: #e8eaef;
    --modern-text-secondary: #a8b0bf;
    --modern-text-tertiary: #707888;
    --modern-text-quaternary: #555b6b;
    --modern-text-link: #6b8aff;
    --modern-text-on-primary: #ffffff;
    --modern-border: #363a47;
    --modern-border-light: #2d313d;
    --modern-border-hover: #454a59;
    --modern-shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --modern-shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --modern-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
    --modern-shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
}

/* Global Reset */
body.modern-body {
    font-family: var(--modern-font-family);
    font-size: var(--modern-font-size-base);
    line-height: var(--modern-line-height);
    color: var(--modern-text-primary);
    background: var(--modern-surface-secondary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}
.modern-body a { color: var(--modern-text-link); transition: color var(--modern-transition-fast); }
.modern-body a:hover { color: var(--modern-primary-hover); }
.modern-body img { max-width: 100%; height: auto; }
.modern-body *, .modern-body *::before, .modern-body *::after { box-sizing: border-box; }

/* Card Component */
.modern-card {
    background: var(--modern-surface);
    border: 1px solid var(--modern-border-light);
    border-radius: var(--modern-radius-md);
    box-shadow: var(--modern-shadow-sm);
    transition: box-shadow var(--modern-transition-base), border-color var(--modern-transition-base), transform var(--modern-transition-base);
}
.modern-card:hover { box-shadow: var(--modern-shadow-md); border-color: var(--modern-border); }
.modern-card--flat { box-shadow: none; }
.modern-card--padded { padding: var(--modern-space-5); }
.modern-card--clickable { cursor: pointer; }
.modern-card--clickable:hover { transform: translateY(-2px); box-shadow: var(--modern-shadow-lg); }

/* Button System */
.modern-btn {
    display: inline-flex; align-items: center; justify-content: center;
    gap: var(--modern-space-2); padding: 8px 16px;
    font-family: var(--modern-font-family); font-size: var(--modern-font-size-sm);
    font-weight: 500; line-height: 1.4; border-radius: var(--modern-radius-sm);
    border: 1px solid transparent; cursor: pointer;
    transition: all var(--modern-transition-fast); text-decoration: none;
    white-space: nowrap; user-select: none;
}
.modern-btn--primary { background: var(--modern-primary); color: var(--modern-text-on-primary); border-color: var(--modern-primary); }
.modern-btn--primary:hover { background: var(--modern-primary-hover); border-color: var(--modern-primary-hover); color: var(--modern-text-on-primary); }
.modern-btn--secondary { background: var(--modern-surface); color: var(--modern-text-primary); border-color: var(--modern-border); }
.modern-btn--secondary:hover { background: var(--modern-surface-hover); border-color: var(--modern-border-hover); }
.modern-btn--ghost { background: transparent; color: var(--modern-text-secondary); border-color: transparent; }
.modern-btn--ghost:hover { background: var(--modern-surface-hover); color: var(--modern-text-primary); }
.modern-btn--sm { padding: 5px 10px; font-size: var(--modern-font-size-xs); border-radius: var(--modern-radius-sm); }
.modern-btn--lg { padding: 12px 24px; font-size: var(--modern-font-size-md); border-radius: var(--modern-radius-md); }
.modern-btn--icon { width: 36px; height: 36px; padding: 0; }
.modern-btn--icon.modern-btn--sm { width: 30px; height: 30px; }
.modern-btn--full { width: 100%; }

/* Typography */
.modern-heading-1 { font-size: var(--modern-font-size-3xl); font-weight: 700; line-height: var(--modern-line-height-tight); }
.modern-heading-2 { font-size: var(--modern-font-size-2xl); font-weight: 600; line-height: var(--modern-line-height-tight); }
.modern-heading-3 { font-size: var(--modern-font-size-xl); font-weight: 600; line-height: var(--modern-line-height-tight); }
.modern-heading-4 { font-size: var(--modern-font-size-lg); font-weight: 600; }
.modern-text-xs { font-size: var(--modern-font-size-xs); }
.modern-text-sm { font-size: var(--modern-font-size-sm); }
.modern-text-base { font-size: var(--modern-font-size-base); }
.modern-text-secondary { color: var(--modern-text-secondary); }
.modern-text-tertiary { color: var(--modern-text-tertiary); }
.modern-text-primary { color: var(--modern-text-primary); }
.modern-font-mono { font-family: var(--modern-font-mono); }
.modern-font-medium { font-weight: 500; }
.modern-font-semibold { font-weight: 600; }
.modern-font-bold { font-weight: 700; }

/* Badge & Tag */
.modern-badge {
    display: inline-flex; align-items: center;
    padding: 2px 8px; font-size: var(--modern-font-size-xs);
    font-weight: 500; line-height: 1.5;
    border-radius: var(--modern-radius-full); white-space: nowrap;
}
.modern-badge--primary { background: var(--modern-primary-light); color: var(--modern-primary); }
.modern-badge--success { background: var(--modern-success-light); color: var(--modern-success); }
.modern-badge--warning { background: var(--modern-warning-light); color: var(--modern-warning); }
.modern-badge--danger { background: var(--modern-danger-light); color: var(--modern-danger); }
.modern-badge--info { background: var(--modern-info-light); color: var(--modern-info); }

/* Avatar */
.modern-avatar {
    display: inline-flex; align-items: center; justify-content: center;
    border-radius: var(--modern-radius-avatar); overflow: hidden; flex-shrink: 0;
    background: var(--modern-surface-tertiary); color: var(--modern-text-secondary); font-weight: 600;
}
.modern-avatar img { width: 100%; height: 100%; object-fit: cover; }
.modern-avatar--xs { width: 24px; height: 24px; font-size: 10px; }
.modern-avatar--sm { width: 32px; height: 32px; font-size: 12px; }
.modern-avatar--md { width: 40px; height: 40px; font-size: 16px; }
.modern-avatar--lg { width: 56px; height: 56px; font-size: 24px; }
.modern-avatar--xl { width: 72px; height: 72px; font-size: 32px; }

/* Divider */
.modern-divider { border: none; border-top: 1px solid var(--modern-border-light); margin: var(--modern-space-4) 0; }

/* Flex & Grid Helpers */
.modern-flex { display: flex; }
.modern-flex-col { flex-direction: column; }
.modern-flex-wrap { flex-wrap: wrap; }
.modern-flex-1 { flex: 1; }
.modern-items-center { align-items: center; }
.modern-items-start { align-items: flex-start; }
.modern-justify-between { justify-content: space-between; }
.modern-justify-center { justify-content: center; }
.modern-gap-1 { gap: var(--modern-space-1); }
.modern-gap-2 { gap: var(--modern-space-2); }
.modern-gap-3 { gap: var(--modern-space-3); }
.modern-gap-4 { gap: var(--modern-space-4); }
.modern-gap-6 { gap: var(--modern-space-6); }

/* Spacing */
.modern-p-0 { padding: 0; }
.modern-p-2 { padding: var(--modern-space-2); }
.modern-p-3 { padding: var(--modern-space-3); }
.modern-p-4 { padding: var(--modern-space-4); }
.modern-p-5 { padding: var(--modern-space-5); }
.modern-p-6 { padding: var(--modern-space-6); }
.modern-px-4 { padding-left: var(--modern-space-4); padding-right: var(--modern-space-4); }
.modern-px-5 { padding-left: var(--modern-space-5); padding-right: var(--modern-space-5); }
.modern-py-2 { padding-top: var(--modern-space-2); padding-bottom: var(--modern-space-2); }
.modern-py-3 { padding-top: var(--modern-space-3); padding-bottom: var(--modern-space-3); }
.modern-py-4 { padding-top: var(--modern-space-4); padding-bottom: var(--modern-space-4); }
.modern-mb-2 { margin-bottom: var(--modern-space-2); }
.modern-mb-3 { margin-bottom: var(--modern-space-3); }
.modern-mb-4 { margin-bottom: var(--modern-space-4); }
.modern-mb-6 { margin-bottom: var(--modern-space-6); }
.modern-mt-2 { margin-top: var(--modern-space-2); }
.modern-mt-4 { margin-top: var(--modern-space-4); }
.modern-mt-6 { margin-top: var(--modern-space-6); }

/* Text Utils */
.modern-text-center { text-align: center; }
.modern-text-left { text-align: left; }
.modern-text-right { text-align: right; }
.modern-text-truncate { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.modern-text-clamp-2 { display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }

/* Skeleton Loading */
.modern-skeleton {
    background: linear-gradient(90deg, var(--modern-surface-tertiary) 25%, var(--modern-surface-hover) 50%, var(--modern-surface-tertiary) 75%);
    background-size: 200% 100%; animation: modern-skeleton 1.5s infinite; border-radius: var(--modern-radius-sm);
}
@keyframes modern-skeleton { 0% { background-position: 200% 0; } 100% { background-position: -200% 0; } }
.modern-skeleton--text { height: 14px; margin-bottom: 8px; }
.modern-skeleton--title { height: 20px; width: 60%; margin-bottom: 12px; }
.modern-skeleton--avatar { width: 40px; height: 40px; border-radius: var(--modern-radius-avatar); }
.modern-skeleton--card { height: 80px; margin-bottom: var(--modern-space-3); }

/* Transitions */
.modern-transition-fade { transition: opacity var(--modern-transition-base); }
.modern-transition-all { transition: all var(--modern-transition-fast); }
.modern-hover-lift { transition: transform var(--modern-transition-base), box-shadow var(--modern-transition-base); }
.modern-hover-lift:hover { transform: translateY(-2px); box-shadow: var(--modern-shadow-lg); }

/* Animations */
@keyframes modern-fade-in { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
@keyframes modern-fade-in-up { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: translateY(0); } }
@keyframes modern-slide-in-right { from { opacity: 0; transform: translateX(16px); } to { opacity: 1; transform: translateX(0); } }
.modern-animate-fade-in { animation: modern-fade-in var(--modern-transition-slow) ease-out forwards; }
.modern-animate-fade-in-up { animation: modern-fade-in-up var(--modern-transition-slow) ease-out forwards; }

/* Stagger delays */
.modern-stagger > *:nth-child(1) { animation-delay: 0ms; }
.modern-stagger > *:nth-child(2) { animation-delay: 50ms; }
.modern-stagger > *:nth-child(3) { animation-delay: 100ms; }
.modern-stagger > *:nth-child(4) { animation-delay: 150ms; }
.modern-stagger > *:nth-child(5) { animation-delay: 200ms; }
.modern-stagger > *:nth-child(6) { animation-delay: 250ms; }
.modern-stagger > *:nth-child(7) { animation-delay: 300ms; }
.modern-stagger > *:nth-child(8) { animation-delay: 350ms; }
.modern-stagger > *:nth-child(9) { animation-delay: 400ms; }
.modern-stagger > *:nth-child(10) { animation-delay: 450ms; }