/* ==========================================================================
   LeetCode 150 Roadmap Tracker — Modern Design System
   ========================================================================== */

:root {
    /* Color Palette - Dark Theme Default */
    --bg-base: #0a0d14;
    --bg-surface: #101622;
    --bg-surface-elevated: #161f31;
    --bg-glass: rgba(16, 22, 34, 0.75);
    --border-subtle: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.18);
    --border-accent: rgba(99, 102, 241, 0.35);

    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-inverse: #0b0f19;

    /* Accents */
    --accent-primary: #6366f1;
    --accent-primary-hover: #4f46e5;
    --accent-glow: rgba(99, 102, 241, 0.25);
    --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
    --accent-cyan: #06b6d4;

    /* Difficulty Badges */
    --diff-easy: #10b981;
    --diff-easy-bg: rgba(16, 185, 129, 0.12);
    --diff-easy-border: rgba(16, 185, 129, 0.25);
    
    --diff-medium: #f59e0b;
    --diff-medium-bg: rgba(245, 158, 11, 0.12);
    --diff-medium-border: rgba(245, 158, 11, 0.25);

    --diff-hard: #ef4444;
    --diff-hard-bg: rgba(239, 68, 68, 0.12);
    --diff-hard-border: rgba(239, 68, 68, 0.25);

    /* UI Tokens */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.35);
    --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.2);

    --transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
}

[data-theme="light"] {
    --bg-base: #f8fafc;
    --bg-surface: #ffffff;
    --bg-surface-elevated: #f1f5f9;
    --bg-glass: rgba(255, 255, 255, 0.85);
    --border-subtle: rgba(0, 0, 0, 0.08);
    --border-hover: rgba(0, 0, 0, 0.18);
    --border-accent: rgba(99, 102, 241, 0.3);

    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --text-inverse: #ffffff;

    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.08);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.15);
}

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

body {
    font-family: var(--font-sans);
    background-color: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
    background-image: 
        radial-gradient(circle at 15% 10%, rgba(99, 102, 241, 0.08) 0%, transparent 40%),
        radial-gradient(circle at 85% 60%, rgba(168, 85, 247, 0.06) 0%, transparent 40%);
    background-attachment: fixed;
}

.app-container {
    max-width: 1440px;
    margin: 0 auto;
    padding: 1rem 1.5rem 3rem;
}

/* ==========================================================================
   Navigation & CodeByArt Branding
   ========================================================================== */
.top-nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1.25rem;
    background: var(--bg-glass);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 1rem;
    z-index: 100;
    gap: 1rem;
}

.logo-link {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: inherit;
    flex-shrink: 0;
}

.logo-emblem {
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.logo-link:hover .logo-emblem {
    transform: scale(1.06);
    filter: drop-shadow(0 0 10px rgba(99, 102, 241, 0.5));
}

.logo-info {
    display: flex;
    flex-direction: column;
}

.logo-brand {
    font-size: 1.15rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    line-height: 1.1;
}

.logo-code {
    color: var(--text-primary);
}

.logo-art {
    background: linear-gradient(135deg, #00e5ff 0%, #a855f7 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo-sub {
    font-size: 0.65rem;
    font-family: var(--font-mono);
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    font-weight: 600;
}

.nav-tabs {
    display: flex;
    align-items: center;
    gap: 0.35rem;
    background: var(--bg-surface-elevated);
    padding: 0.25rem 0.35rem;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-subtle);
    flex-shrink: 0;
}

.nav-tab {
    display: inline-flex;
    align-items: center;
    gap: 0.45rem;
    padding: 0.45rem 0.85rem;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.825rem;
    font-weight: 600;
    transition: var(--transition);
    white-space: nowrap;
}

.nav-tab:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-tab.active {
    background: var(--accent-gradient);
    color: #ffffff;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.35);
}

/* Nav More Dropdown */
.nav-more-dropdown {
    position: relative;
    display: inline-flex;
    align-items: center;
}

.nav-more-trigger {
    background: transparent;
    border: none;
    cursor: pointer;
    font-family: inherit;
    line-height: inherit;
}

.nav-more-trigger:hover,
.nav-more-dropdown:hover .nav-more-trigger,
.nav-more-dropdown.open .nav-more-trigger {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

.nav-more-trigger .more-caret {
    display: inline-block;
    transition: transform 0.2s ease;
    font-size: 0.65rem;
    margin-left: 0.15rem;
}

.nav-more-dropdown:hover .more-caret,
.nav-more-dropdown.open .more-caret {
    transform: rotate(180deg);
}

.nav-more-menu {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    width: 250px;
    background: var(--bg-surface-elevated, #161f31);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-subtle, rgba(255, 255, 255, 0.12));
    border-radius: var(--radius-md, 10px);
    box-shadow: 0 16px 36px rgba(0, 0, 0, 0.5), 0 4px 12px rgba(0, 0, 0, 0.3);
    padding: 0.5rem;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px);
    transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1),
                transform 0.2s cubic-bezier(0.16, 1, 0.3, 1),
                visibility 0.2s;
    pointer-events: none;
}

.nav-more-dropdown:hover .nav-more-menu,
.nav-more-dropdown.open .nav-more-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    pointer-events: auto;
}

.nav-more-header {
    font-size: 0.66rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted, #64748b);
    padding: 0.4rem 0.6rem 0.25rem;
}

.nav-more-item {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    padding: 0.55rem 0.65rem;
    border-radius: var(--radius-sm, 6px);
    color: var(--text-secondary, #cbd5e1);
    text-decoration: none !important;
    transition: var(--transition);
}

.nav-more-item:hover {
    background: rgba(99, 102, 241, 0.12);
    color: #ffffff;
    text-decoration: none !important;
}

.nav-more-item.active {
    background: rgba(99, 102, 241, 0.18);
    color: var(--accent-primary, #6366f1);
}

.nav-more-item-icon {
    width: 22px;
    height: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1rem;
    flex-shrink: 0;
}

.nav-more-item-text {
    display: flex;
    flex-direction: column;
    min-width: 0;
    flex: 1;
}

.nav-more-item-title {
    font-weight: 600;
    font-size: 0.8rem;
    color: var(--text-primary, #f1f5f9);
    line-height: 1.25;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.nav-more-item-desc {
    font-size: 0.68rem;
    color: var(--text-muted, #94a3b8);
    line-height: 1.2;
    margin-top: 2px;
}

[data-theme="light"] .nav-more-menu {
    background: #ffffff;
    border-color: rgba(0, 0, 0, 0.1);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.12);
}

[data-theme="light"] .nav-more-item:hover {
    background: rgba(99, 102, 241, 0.08);
}

[data-theme="light"] .nav-more-item-title {
    color: #1e293b;
}

.nav-right-group {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-left: auto;
}

.nav-network {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.network-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.35rem 0.65rem;
    border-radius: 99px;
    font-size: 0.74rem;
    font-weight: 600;
    text-decoration: none;
    border: 1px solid var(--border-subtle);
    background: var(--bg-surface-elevated);
    color: var(--text-secondary);
    transition: var(--transition);
    white-space: nowrap;
}

.network-badge:hover {
    transform: translateY(-1px);
    border-color: var(--border-hover);
    color: var(--text-primary);
}

.cba-badge:hover {
    border-color: rgba(0, 229, 255, 0.4);
    color: #00e5ff;
    background: rgba(0, 229, 255, 0.08);
}

.ck-badge:hover {
    border-color: rgba(168, 85, 247, 0.4);
    color: #c084fc;
    background: rgba(168, 85, 247, 0.08);
}

.linkedin-badge:hover {
    border-color: rgba(10, 102, 194, 0.5);
    color: #38bdf8;
    background: rgba(10, 102, 194, 0.12);
}

.mail-badge:hover {
    border-color: rgba(239, 68, 68, 0.4);
    color: #f87171;
    background: rgba(239, 68, 68, 0.08);
}

/* Header Dropdown Menu */
.header-dropdown {
    position: relative;
    display: inline-flex;
    align-items: center;
}

.dropdown-trigger {
    cursor: pointer;
    font-family: inherit;
    border: 1px solid var(--border-subtle);
    background: var(--bg-surface-elevated);
    color: var(--text-secondary);
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.35rem 0.65rem;
    border-radius: 99px;
    font-size: 0.74rem;
    font-weight: 600;
    transition: var(--transition);
}

.dropdown-trigger:hover,
.header-dropdown.open .dropdown-trigger {
    color: var(--text-primary);
    border-color: var(--border-accent);
    background: var(--bg-surface);
}

.dropdown-caret {
    transition: transform 0.2s ease;
    opacity: 0.7;
}

.header-dropdown:hover .dropdown-caret,
.header-dropdown.open .dropdown-caret {
    transform: rotate(180deg);
}

.dropdown-menu {
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    width: 250px;
    background: var(--bg-surface-elevated);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    box-shadow: 0 12px 32px rgba(0, 0, 0, 0.36), 0 4px 12px rgba(0, 0, 0, 0.2);
    padding: 0.5rem;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px);
    transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1), 
                transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), 
                visibility 0.2s;
    pointer-events: none;
}

.header-dropdown:hover .dropdown-menu,
.header-dropdown.open .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
    pointer-events: auto;
}

.dropdown-header {
    font-size: 0.66rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    padding: 0.4rem 0.6rem 0.3rem;
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    padding: 0.55rem 0.65rem;
    border-radius: var(--radius-sm);
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.dropdown-item:hover {
    background: rgba(99, 102, 241, 0.08);
    color: var(--text-primary);
}

.dropdown-item-icon {
    width: 22px;
    height: 22px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.95rem;
    flex-shrink: 0;
}

.dropdown-item-text {
    display: flex;
    flex-direction: column;
    min-width: 0;
    flex: 1;
}

.dropdown-item-title {
    font-weight: 600;
    font-size: 0.8rem;
    color: var(--text-primary);
    line-height: 1.2;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.dropdown-item-desc {
    font-size: 0.68rem;
    color: var(--text-muted);
    line-height: 1.2;
    margin-top: 2px;
}

.dropdown-external {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-left: auto;
    opacity: 0.6;
}

.dropdown-divider {
    height: 1px;
    background: var(--border-subtle);
    margin: 0.35rem 0;
}



.badge-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: #00e5ff;
    box-shadow: 0 0 6px #00e5ff;
}

.linkedin-svg {
    flex-shrink: 0;
}

.nav-divider {
    height: 22px;
    width: 1px;
    background: var(--border-subtle);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.nav-btn {
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    color: var(--text-primary);
    padding: 0.45rem 0.7rem;
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95rem;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
}

.nav-btn:hover {
    background: var(--bg-surface);
    border-color: var(--border-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.nav-btn.danger:hover {
    background: rgba(239, 68, 68, 0.15);
    border-color: rgba(239, 68, 68, 0.3);
}

.import-btn {
    cursor: pointer;
}

/* ==========================================================================
   Hero & Dashboard Stats
   ========================================================================== */
.hero {
    margin-bottom: 2rem;
}

.hero-grid {
    display: grid;
    grid-template-columns: 240px 180px 220px 240px 1fr;
    gap: 1.25rem;
}

.stat-card {
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.stat-card:hover {
    border-color: var(--border-accent);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.hero-card {
    align-items: center;
    text-align: center;
    padding: 1.25rem 1rem;
}

.progress-ring-container {
    position: relative;
    width: 110px;
    height: 110px;
}

.progress-ring {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.progress-ring-bg {
    fill: none;
    stroke: var(--bg-surface-elevated);
    stroke-width: 9;
}

.progress-ring-fill {
    fill: none;
    stroke: url(#ring-gradient);
    stroke: var(--accent-primary);
    stroke-width: 9;
    stroke-linecap: round;
    stroke-dasharray: 326.72;
    stroke-dashoffset: 326.72;
    transition: stroke-dashoffset 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.progress-ring-text {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    display: flex;
    flex-direction: column;
}

.ring-value {
    font-size: 1.35rem;
    font-weight: 800;
    font-family: var(--font-mono);
    color: var(--text-primary);
    line-height: 1;
}

.ring-label {
    font-size: 0.7rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 2px;
}

.stat-detail {
    margin-top: 0.75rem;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.stat-icon {
    font-size: 1.5rem;
    margin-bottom: 0.4rem;
}

.stat-value {
    font-size: 2rem;
    font-weight: 800;
    font-family: var(--font-mono);
    color: var(--text-primary);
    line-height: 1.1;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-top: 0.25rem;
}

.stat-sub {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.35rem;
}

/* Difficulty breakdown in stats */
.difficulty-bars {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-top: 0.25rem;
}

.diff-bar-row {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.75rem;
}

.diff-label {
    width: 38px;
    font-weight: 700;
}
.diff-label.easy { color: var(--diff-easy); }
.diff-label.medium { color: var(--diff-medium); }
.diff-label.hard { color: var(--diff-hard); }

.diff-bar-track {
    flex: 1;
    height: 6px;
    background: var(--bg-surface-elevated);
    border-radius: 99px;
    overflow: hidden;
}

.diff-bar-fill {
    height: 100%;
    width: 0%;
    border-radius: 99px;
    transition: width 0.6s ease;
}
.diff-bar-fill.easy { background: var(--diff-easy); }
.diff-bar-fill.medium { background: var(--diff-medium); }
.diff-bar-fill.hard { background: var(--diff-hard); }

.diff-count {
    width: 48px;
    text-align: right;
    font-family: var(--font-mono);
    color: var(--text-muted);
    font-size: 0.7rem;
}

/* Heatmap Grid */
.stat-card-wide {
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
}

.heatmap {
    display: grid;
    grid-template-columns: repeat(18, 1fr);
    grid-template-rows: repeat(5, 1fr);
    gap: 4px;
    margin-top: auto;
}

.heat-cell {
    aspect-ratio: 1;
    border-radius: 3px;
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    cursor: pointer;
    position: relative;
    transition: var(--transition);
}

.heat-cell:hover {
    transform: scale(1.3);
    z-index: 10;
    box-shadow: 0 0 8px rgba(99, 102, 241, 0.5);
    border-color: var(--accent-primary);
}

.heat-cell.empty { background: rgba(255, 255, 255, 0.04); }
.heat-cell.partial { background: rgba(245, 158, 11, 0.4); border-color: rgba(245, 158, 11, 0.6); }
.heat-cell.complete { background: #10b981; border-color: #059669; }
.heat-cell.today { outline: 2px solid var(--accent-primary); outline-offset: 1px; }

/* Tooltip for heat-cell */
.heat-cell::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--bg-surface-elevated);
    color: var(--text-primary);
    padding: 3px 6px;
    border-radius: var(--radius-sm);
    font-size: 0.65rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.15s ease;
    border: 1px solid var(--border-hover);
    box-shadow: var(--shadow-sm);
    z-index: 20;
}
.heat-cell:hover::after {
    opacity: 1;
}

/* ==========================================================================
   Controls Bar & Filtering
   ========================================================================== */
.controls-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 1.5rem;
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 0.75rem 1rem;
    align-items: center;
}

.search-box {
    flex: 1 1 260px;
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon {
    position: absolute;
    left: 0.85rem;
    font-size: 0.9rem;
    opacity: 0.6;
    pointer-events: none;
}

.search-box input {
    width: 100%;
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 0.55rem 0.75rem 0.55rem 2.25rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.875rem;
    transition: var(--transition);
}

.search-box input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.filter-group {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

select {
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 0.55rem 0.85rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--transition);
}

select:focus {
    outline: none;
    border-color: var(--accent-primary);
}

select option {
    background: var(--bg-surface);
    color: var(--text-primary);
}

/* ==========================================================================
   Problems Table
   ========================================================================== */
.problems-section {
    margin-bottom: 2.5rem;
}

.table-container {
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.problems-table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
    font-size: 0.875rem;
}

.problems-table th {
    background: var(--bg-surface-elevated);
    padding: 0.85rem 1rem;
    font-weight: 700;
    color: var(--text-secondary);
    text-transform: uppercase;
    font-size: 0.72rem;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--border-subtle);
    position: sticky;
    top: 0;
}

.problems-table td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-subtle);
    transition: var(--transition);
}

.problems-table tr:last-child td {
    border-bottom: none;
}

.problems-table tbody tr {
    transition: var(--transition);
}

.problems-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.02);
}

/* Row states */
.problem-row.completed {
    opacity: 0.65;
    background: rgba(16, 185, 129, 0.03);
}

.problem-row.completed .problem-title {
    text-decoration: line-through;
    color: var(--text-muted);
}

.problem-row.review-row {
    background: rgba(99, 102, 241, 0.05);
}

.problem-row.review-row:hover {
    background: rgba(99, 102, 241, 0.08);
}

/* Column Specific Styles */
.col-check { width: 44px; text-align: center; }
.col-day { width: 75px; }
.col-num { width: 60px; font-family: var(--font-mono); }
.col-pattern { width: 160px; }
.col-diff { width: 100px; }
.col-actions { width: 110px; text-align: right; }

/* Custom Checkbox */
.custom-checkbox {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    position: relative;
    cursor: pointer;
    user-select: none;
}

.custom-checkbox input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    height: 20px;
    width: 20px;
    background-color: var(--bg-surface-elevated);
    border: 1px solid var(--border-hover);
    border-radius: var(--radius-sm);
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
}

.custom-checkbox:hover input ~ .checkmark {
    border-color: var(--accent-primary);
    transform: scale(1.08);
}

.custom-checkbox input:checked ~ .checkmark {
    background-color: #10b981;
    border-color: #10b981;
    box-shadow: 0 0 10px rgba(16, 185, 129, 0.35);
}

.checkmark::after {
    content: "✓";
    display: none;
    color: white;
    font-size: 13px;
    font-weight: 800;
}

.custom-checkbox input:checked ~ .checkmark::after {
    display: block;
}

/* Badges & Tags */
.day-badge {
    display: inline-block;
    padding: 2px 7px;
    font-size: 0.72rem;
    font-weight: 700;
    font-family: var(--font-mono);
    border-radius: var(--radius-sm);
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    color: var(--text-secondary);
}

.pattern-badge {
    display: inline-block;
    padding: 3px 8px;
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    background: rgba(99, 102, 241, 0.1);
    color: #818cf8;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.pattern-badge.review-badge {
    background: rgba(245, 158, 11, 0.12);
    color: #f59e0b;
    border-color: rgba(245, 158, 11, 0.25);
}

.difficulty-badge {
    display: inline-block;
    padding: 3px 8px;
    font-size: 0.72rem;
    font-weight: 700;
    border-radius: var(--radius-sm);
    letter-spacing: 0.02em;
}

.difficulty-badge.easy {
    background: var(--diff-easy-bg);
    color: var(--diff-easy);
    border: 1px solid var(--diff-easy-border);
}

.difficulty-badge.medium {
    background: var(--diff-medium-bg);
    color: var(--diff-medium);
    border: 1px solid var(--diff-medium-border);
}

.difficulty-badge.hard {
    background: var(--diff-hard-bg);
    color: var(--diff-hard);
    border: 1px solid var(--diff-hard-border);
}

.problem-link-wrapper {
    display: flex;
    align-items: center;
    gap: 0.4rem;
}

.problem-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
}

.problem-link:hover {
    color: var(--accent-primary);
    text-decoration: underline;
}

.ext-icon {
    font-size: 0.75rem;
    opacity: 0.4;
    transition: var(--transition);
}

.problem-link:hover .ext-icon {
    opacity: 1;
    transform: translate(2px, -2px);
}

/* Action Buttons */
.action-btn-group {
    display: inline-flex;
    gap: 0.3rem;
}

.btn-icon {
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    color: var(--text-secondary);
    width: 28px;
    height: 28px;
    border-radius: var(--radius-sm);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 0.8rem;
    transition: var(--transition);
    text-decoration: none;
}

.btn-icon:hover {
    background: var(--bg-surface);
    color: var(--text-primary);
    border-color: var(--border-hover);
    transform: translateY(-1px);
}

.btn-icon.has-notes {
    background: rgba(99, 102, 241, 0.2);
    border-color: var(--accent-primary);
    color: #818cf8;
}

/* ==========================================================================
   Pattern Grid Section
   ========================================================================== */
.pattern-section {
    margin-bottom: 2.5rem;
}

.section-title {
    font-size: 1.25rem;
    font-weight: 800;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.pattern-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1rem;
}

.pattern-card {
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 1rem;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.pattern-card:hover {
    border-color: var(--border-accent);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.pattern-card.active-filter {
    border-color: var(--accent-primary);
    box-shadow: 0 0 15px var(--accent-glow);
}

.pattern-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.pattern-name {
    font-weight: 700;
    font-size: 0.9rem;
}

.pattern-stats {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.pattern-progress-track {
    height: 5px;
    background: var(--bg-surface-elevated);
    border-radius: 99px;
    overflow: hidden;
}

.pattern-progress-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: 99px;
    transition: width 0.5s ease;
}

/* ==========================================================================
   Modals & Toast
   ========================================================================== */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(6px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 1;
    transition: opacity 0.2s ease;
}

.modal-overlay.hidden {
    opacity: 0;
    pointer-events: none;
    display: none;
}

.modal {
    background: var(--bg-surface);
    border: 1px solid var(--border-hover);
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 520px;
    box-shadow: var(--shadow-md);
    overflow: hidden;
    animation: modalPop 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.modal.modal-sm {
    max-width: 420px;
}

@keyframes modalPop {
    from { transform: scale(0.92); opacity: 0; }
    to { transform: scale(1); opacity: 1; }
}

.modal-header {
    padding: 1.25rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid var(--border-subtle);
}

.modal-header h2 {
    font-size: 1.15rem;
    font-weight: 700;
}

.modal-close {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.5rem;
    cursor: pointer;
    line-height: 1;
    transition: var(--transition);
}

.modal-close:hover {
    color: var(--text-primary);
}

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-subtle);
    display: flex;
    justify-content: flex-end;
    gap: 0.75rem;
    background: var(--bg-surface-elevated);
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.4rem;
}

.form-group input[type="text"],
.form-group input[type="time"],
.modal-body textarea {
    width: 100%;
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-md);
    padding: 0.65rem 0.85rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.9rem;
    transition: var(--transition);
}

.form-group input:focus,
.modal-body textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.modal-body textarea {
    font-family: var(--font-mono);
    font-size: 0.85rem;
    resize: vertical;
}

/* Toggle Switch */
.toggle-label {
    display: flex !important;
    align-items: center;
    justify-content: space-between;
    cursor: pointer;
}

/* Buttons */
.btn {
    padding: 0.55rem 1.1rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    border: none;
    transition: var(--transition);
}

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

.btn-primary:hover {
    opacity: 0.92;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.35);
}

.btn-secondary {
    background: var(--bg-surface);
    color: var(--text-secondary);
    border: 1px solid var(--border-subtle);
}

.btn-secondary:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
}

.btn-danger {
    background: #ef4444;
    color: white;
}

.btn-danger:hover {
    background: #dc2626;
}

/* Reminder Toast Notification */
.reminder-toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: var(--bg-surface);
    border: 1px solid var(--accent-primary);
    border-radius: var(--radius-lg);
    padding: 1rem 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    box-shadow: var(--shadow-md), 0 0 20px var(--accent-glow);
    z-index: 2000;
    animation: toastSlide 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    max-width: 380px;
}

.reminder-toast.hidden {
    display: none;
}

@keyframes toastSlide {
    from { transform: translateY(50px); opacity: 0; }
    to { transform: translateY(0); opacity: 1; }
}

.toast-icon { font-size: 1.5rem; }
.toast-content { flex: 1; }
.toast-title { display: block; font-weight: 700; font-size: 0.85rem; }
.toast-msg { display: block; font-size: 0.8rem; color: var(--text-secondary); margin-top: 2px; }
.toast-close {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.25rem;
    cursor: pointer;
}

/* ==========================================================================
   Footer Styles
   ========================================================================== */
.footer {
    padding: 2.5rem 0 1.5rem;
    color: var(--text-muted);
    font-size: 0.85rem;
    border-top: 1px solid var(--border-subtle);
    margin-top: 3rem;
}

.footer-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-brand .logo-brand {
    font-size: 1.25rem;
}

.footer-tagline {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
}

.footer-credit {
    font-size: 0.82rem;
    margin-top: 0.4rem;
    color: var(--text-muted);
}

.footer-link {
    color: var(--accent-cyan);
    text-decoration: none;
    font-weight: 600;
}
.footer-link:hover { text-decoration: underline; }

.footer-links {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.footer-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.45rem 0.85rem;
    border-radius: 99px;
    background: var(--bg-surface-elevated);
    border: 1px solid var(--border-subtle);
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.78rem;
    font-weight: 600;
    transition: var(--transition);
}

.footer-pill:hover {
    color: var(--text-primary);
    border-color: var(--border-hover);
    transform: translateY(-1px);
}

.linkedin-pill:hover {
    color: #38bdf8;
    border-color: rgba(10, 102, 194, 0.5);
    background: rgba(10, 102, 194, 0.12);
}

.footer-bottom {
    text-align: center;
    padding-top: 1.25rem;
    border-top: 1px solid var(--border-subtle);
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* ==========================================================================
   Responsive Adaptations
   ========================================================================== */
@media (max-width: 1200px) {
    .hero-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .stat-card-wide {
        grid-column: span 2;
    }
}

@media (max-width: 1100px) {
    .top-nav {
        flex-wrap: wrap;
        gap: 0.85rem;
    }
    .nav-tabs {
        order: 3;
        width: 100%;
        justify-content: center;
    }
    .nav-right-group {
        margin-left: auto;
    }
}

@media (max-width: 768px) {
    .app-container {
        padding: 0.75rem 1rem 2.5rem;
    }
    .top-nav {
        padding: 0.85rem 1rem;
        border-radius: var(--radius-md);
        gap: 0.75rem;
    }
    .nav-network {
        display: none;
    }
    .nav-tabs {
        order: 2;
        width: 100%;
        justify-content: flex-start;
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
        scrollbar-width: none;
    }
    .nav-tabs::-webkit-scrollbar {
        display: none;
    }
    .nav-tab {
        padding: 0.45rem 0.7rem;
        font-size: 0.78rem;
    }
    .footer-container {
        flex-direction: column;
        align-items: flex-start;
    }
    .hero-grid {
        grid-template-columns: 1fr;
    }
    .stat-card-wide {
        grid-column: span 1;
    }
    .controls-bar {
        flex-direction: column;
        align-items: stretch;
    }
    .filter-group {
        flex-direction: column;
    }
    .problems-table th, .problems-table td {
        padding: 0.6rem 0.5rem;
        font-size: 0.8rem;
    }
    .col-pattern {
        display: none;
    }
}

/* Companion Links Section */
.companions-section {
    margin-top: 3rem;
    margin-bottom: 2rem;
}

.companions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 1.25rem;
    margin-top: 1rem;
}

.companion-card {
    background: var(--bg-glass);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-subtle);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.companion-card:hover {
    border-color: var(--accent-primary);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.companion-card-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
}

.companion-icon {
    font-size: 1.75rem;
}

.companion-title {
    font-size: 1.15rem;
    font-weight: 700;
}

.companion-desc {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.5;
    margin-bottom: 1rem;
}

.companion-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--accent-primary);
}

/* ==========================================================================
   Footer Styling
   ========================================================================== */
.footer {
    margin-top: 3.5rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-subtle);
}

.footer-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-brand .logo-info {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}

.footer-tagline {
    font-size: 0.82rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

.footer-credit {
    font-size: 0.82rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}

.footer-link {
    color: var(--accent-primary);
    text-decoration: none;
    font-weight: 600;
}

.footer-link:hover {
    text-decoration: underline;
}

.footer-links {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.6rem;
}

.footer-pill {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.45rem 0.85rem;
    border-radius: 99px;
    font-size: 0.78rem;
    font-weight: 600;
    text-decoration: none;
    border: 1px solid var(--border-subtle);
    background: var(--bg-surface-elevated);
    color: var(--text-secondary);
    transition: var(--transition);
}

.footer-pill:hover {
    border-color: var(--border-accent);
    color: var(--text-primary);
    transform: translateY(-1px);
}

.footer-pill.mail-pill:hover {
    border-color: rgba(239, 68, 68, 0.4);
    color: #f87171;
}

.footer-bottom {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-align: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-subtle);
}