/* ==========================================================================
   Sudoku Mind Master - Core Mobile-First Responsive PWA Styles
   ========================================================================== */

:root, [data-bs-theme="dark"] {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #ec4899;
    --accent-warning: #f59e0b;
    --accent-success: #10b981;
    --accent-danger: #ef4444;
    
    --board-bg: #1e1e2e;
    --cell-bg: #2b2b40;
    --cell-text: #f8fafc;
    --cell-initial-text: #818cf8;
    --cell-selected: #3b82f6;
    --cell-selected-text: #ffffff;
    --cell-related: #312e52;
    --cell-match: #4338ca;
    --cell-match-text: #ffffff;
    --cell-error: #7f1d1d;
    --cell-error-text: #ffffff;
    
    --text-primary: #f8fafc;
    --text-muted: #94a3b8;
    --grid-line: #475569;
    --grid-line-thick: #818cf8;
    --font-family: 'Inter', system-ui, -apple-system, sans-serif;

    /* Theme-specific UI variables */
    --header-bg: rgba(30, 30, 46, 0.88);
    --header-border: rgba(255, 255, 255, 0.1);
    --nav-bg: rgba(30, 30, 46, 0.95);
    --nav-border: rgba(255, 255, 255, 0.1);
    --glass-bg: rgba(30, 30, 46, 0.75);
    --glass-border: rgba(255, 255, 255, 0.12);
    --glass-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    --card-bg: #1e1e2e;
    --btn-action-bg: rgba(255, 255, 255, 0.08);
    --btn-action-border: rgba(255, 255, 255, 0.2);
    --btn-action-text: #f8fafc;
    --btn-action-hover: rgba(255, 255, 255, 0.15);
}

[data-bs-theme="light"] {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #db2777;
    --accent-warning: #d97706;
    --accent-success: #059669;
    --accent-danger: #dc2626;

    --board-bg: #ffffff;
    --cell-bg: #f8fafc;
    --cell-text: #0f172a;
    --cell-initial-text: #4338ca;
    --cell-selected: #3b82f6;
    --cell-selected-text: #ffffff;
    --cell-related: #e2e8f0;
    --cell-match: #bfdbfe;
    --cell-match-text: #1e3a8a;
    --cell-error: #fecaca;
    --cell-error-text: #991b1b;

    --text-primary: #0f172a;
    --text-muted: #475569;
    --grid-line: #cbd5e1;
    --grid-line-thick: #4f46e5;

    /* Theme-specific UI variables */
    --header-bg: rgba(255, 255, 255, 0.88);
    --header-border: rgba(0, 0, 0, 0.08);
    --nav-bg: rgba(255, 255, 255, 0.94);
    --nav-border: rgba(0, 0, 0, 0.08);
    --glass-bg: rgba(255, 255, 255, 0.85);
    --glass-border: rgba(0, 0, 0, 0.08);
    --glass-shadow: 0 10px 25px rgba(0, 0, 0, 0.05);
    --card-bg: #ffffff;
    --btn-action-bg: #ffffff;
    --btn-action-border: #cbd5e1;
    --btn-action-text: #1e293b;
    --btn-action-hover: #f1f5f9;
}

body {
    font-family: var(--font-family);
    background-color: var(--bs-body-bg);
    color: var(--text-primary);
    user-select: none;
    -webkit-user-select: none;
    -webkit-touch-callout: none;
    touch-action: manipulation;
    overflow-x: hidden;
}

/* Text Gradient Utility */
.text-gradient {
    background: linear-gradient(135deg, #6366f1 0%, #ec4899 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    display: inline-block;
}

[data-bs-theme="light"] .text-gradient {
    background: linear-gradient(135deg, #4f46e5 0%, #db2777 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Glassmorphism Cards */
.glass-card {
    background: var(--glass-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 1rem;
    box-shadow: var(--glass-shadow);
    color: var(--text-primary);
}

/* Card General Override */
.card {
    background-color: var(--glass-bg);
    border: 1px solid var(--glass-border);
    color: var(--text-primary);
}

/* Header Navbar Styling */
.app-header {
    background: var(--header-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--header-border) !important;
    box-shadow: var(--glass-shadow);
    z-index: 1020;
}

.btn-header-action {
    background: var(--btn-action-bg);
    border: 1px solid var(--btn-action-border);
    color: var(--btn-action-text);
    transition: all 0.2s ease;
}

.btn-header-action:hover {
    background: var(--btn-action-hover);
    color: var(--primary-color);
    border-color: var(--primary-color);
}

/* ==========================================================================
   Sudoku Board Responsive Layout
   ========================================================================== */

.sudoku-container {
    max-width: 500px;
    margin: 0 auto;
    width: 100%;
}

.sudoku-board-wrapper {
    position: relative;
    width: 100%;
    aspect-ratio: 1 / 1;
    padding: 6px;
    background: var(--board-bg);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.15);
    border: 3px solid var(--grid-line-thick);
}

.sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    width: 100%;
    height: 100%;
    gap: 1px;
    background-color: var(--grid-line);
    border-radius: 6px;
    overflow: hidden;
}

.sudoku-cell {
    position: relative;
    background-color: var(--cell-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: clamp(1.2rem, 4vw, 1.8rem);
    font-weight: 700;
    color: var(--cell-text);
    cursor: pointer;
    transition: background-color 0.15s ease, transform 0.1s ease;
}

.sudoku-cell:active {
    transform: scale(0.95);
}

/* Thick Box Borders */
.border-bottom-thick {
    border-bottom: 3px solid var(--grid-line-thick) !important;
}

.border-right-thick {
    border-right: 3px solid var(--grid-line-thick) !important;
}

/* Cell States & Highlights */
.sudoku-cell.initial-num {
    color: var(--cell-initial-text);
    font-weight: 800;
}

.sudoku-cell.selected {
    background-color: var(--cell-selected) !important;
    color: var(--cell-selected-text) !important;
}

.sudoku-cell.highlight-related {
    background-color: var(--cell-related);
}

.sudoku-cell.highlight-match {
    background-color: var(--cell-match);
    color: var(--cell-match-text);
}

.sudoku-cell.cell-error {
    background-color: var(--cell-error) !important;
    color: var(--cell-error-text) !important;
    animation: shake 0.3s ease-in-out;
}

/* Pencil / Notes Grid Inside Cell */
.sudoku-cell.has-notes .notes-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    width: 100%;
    height: 100%;
    padding: 2px;
}

.notes-grid span {
    font-size: clamp(0.55rem, 1.8vw, 0.75rem);
    font-weight: 600;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
}

/* Paused Blur Overlay */
.paused-blur {
    filter: blur(10px);
    pointer-events: none;
}

/* ==========================================================================
   Touch Controls & Keypad
   ========================================================================== */

.number-pad {
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    gap: 6px;
    margin-top: 15px;
}

.num-key {
    position: relative;
    aspect-ratio: 1 / 1.1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    font-size: clamp(1.1rem, 3.5vw, 1.5rem);
    font-weight: 700;
    border-radius: 10px;
    border: 1px solid var(--glass-border);
    background: var(--btn-action-bg);
    color: var(--text-primary);
    box-shadow: 0 3px 6px rgba(0, 0, 0, 0.08);
    transition: all 0.15s ease;
}

.num-key:hover {
    background: var(--btn-action-hover);
    color: var(--primary-color);
}

.num-key:active {
    transform: translateY(2px);
}

.num-key .badge-count {
    font-size: 0.65rem;
    font-weight: 600;
    opacity: 0.75;
    margin-top: 2px;
    color: var(--text-muted);
}

.num-key.completed-num {
    opacity: 0.3;
    pointer-events: none;
}

/* Keypad Action Tools */
.action-tools-row {
    display: flex;
    justify-content: space-around;
    align-items: center;
    margin-top: 12px;
    gap: 8px;
}

.action-tools-row .btn-tool {
    flex: 1;
    padding: 10px 4px;
    font-size: 0.85rem;
    font-weight: 600;
    border-radius: 10px;
    background: var(--btn-action-bg);
    border: 1px solid var(--btn-action-border);
    color: var(--btn-action-text);
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
    transition: all 0.15s ease;
}

.action-tools-row .btn-tool:hover {
    background: var(--btn-action-hover);
    color: var(--primary-color);
}

.action-tools-row .btn-tool.active {
    background: var(--primary-color) !important;
    color: #ffffff !important;
    border-color: var(--primary-color) !important;
}

.action-tools-row .btn-hint-custom {
    background: #f59e0b;
    color: #000000;
    font-weight: 700;
    border: none;
}

.action-tools-row .btn-hint-custom:hover {
    background: #d97706;
    color: #ffffff;
}

/* ==========================================================================
   Navigation Bar & Responsive Header
   ========================================================================== */

.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 65px;
    background: var(--nav-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-top: 1px solid var(--nav-border);
    display: flex;
    justify-content: space-around;
    align-items: center;
    z-index: 1000;
    box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.05);
}

.nav-link-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.75rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.nav-link-item i {
    font-size: 1.3rem;
    margin-bottom: 2px;
}

.nav-link-item:hover {
    color: var(--primary-color);
}

.nav-link-item.active {
    color: var(--primary-color);
    font-weight: 700;
}

/* Modals & Forms */
.modal-content {
    background: var(--glass-bg) !important;
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--glass-border) !important;
    color: var(--text-primary);
}

[data-bs-theme="light"] .form-control {
    background-color: #ffffff;
    color: #0f172a;
    border-color: #cbd5e1;
}

[data-bs-theme="light"] .form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 0.25rem rgba(79, 70, 229, 0.25);
}

/* Profile Stat Items */
.profile-stat-item {
    background: transparent;
    color: var(--text-primary);
    border-color: var(--glass-border);
}

/* Level Locked Card */
.level-locked {
    opacity: 0.6;
    background: var(--cell-bg) !important;
}

/* Banner Ads Styling */
.ad-card.banner-ad {
    position: relative;
    background: linear-gradient(135deg, #312e81, #1e1b4b);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 12px;
    padding: 10px 14px;
    margin-top: 15px;
    color: #ffffff;
}

.ad-badge {
    position: absolute;
    top: 4px;
    right: 8px;
    font-size: 0.6rem;
    background: rgba(0, 0, 0, 0.4);
    padding: 1px 6px;
    border-radius: 4px;
    color: #f59e0b;
}

/* Modal Overlay for Interstitial & Rewarded Ads */
.ad-modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(8px);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.ad-modal-dialog {
    background: var(--board-bg);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    max-width: 400px;
    width: 100%;
    padding: 20px;
    text-align: center;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5);
    color: var(--text-primary);
}

.btn-close-ad {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.85rem;
    cursor: pointer;
}

/* Animations */
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-6px); }
    40%, 80% { transform: translateX(6px); }
}

@keyframes bounce {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

.animate-bounce {
    animation: bounce 2s infinite;
}