@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;600;800&display=swap');

:root {
    --bg-gradient-start: #F8FAFC;
    --bg-gradient-end: #E2E8F0;
    --primary: #2563EB;
    --primary-hover: #1D4ED8;
    --secondary: #06B6D4;
    --secondary-hover: #0891B2;
    --success: #10B981;
    --danger: #EF4444;
    --card-bg: rgba(255, 255, 255, 0.8);
    --card-border: rgba(255, 255, 255, 0.6);
    --text-main: #000000;
    --text-muted: #475569;
    --cell-bg: #FFFFFF;
    --cell-border: #BEC9D4;
    --grid-border: #1E293B;
    
    --cell-fixed-bg: #FFFFFF;
    --cell-hover-bg: #E0F2FE;
    --cell-selected-bg: #A3D5FF;
    --cell-highlight-bg: #CBE5FF;
    --cell-related-bg: #ECF3FC;

    --option-bg: #FFFFFF;
    --select-chevron: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%231F2937' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    --form-bg: rgba(15, 23, 42, 0.05);
    --form-border: rgba(15, 23, 42, 0.15);

    --cell-size: 50px;
    --cell-size-mobile: 10vw;
}

[data-theme="dark"] {
    --bg-gradient-start: #0F172A;
    --bg-gradient-end: #020617;
    --card-bg: rgba(30, 41, 59, 0.85);
    --card-border: rgba(255, 255, 255, 0.1);
    --text-main: #F8FAFC;
    --text-muted: #94A3B8;
    --cell-bg: #1E293B;
    --cell-border: rgba(255, 255, 255, 0.08);
    --grid-border: #475569;

    --cell-fixed-bg: #1E293B;
    --cell-hover-bg: #334155;
    --cell-selected-bg: #1D4ED8;
    --cell-highlight-bg: #1E40AF;
    --cell-related-bg: rgba(148, 163, 184, 0.08);
    --primary: #3B82F6;
    --success: #34D399;

    --option-bg: #1E293B;
    --select-chevron: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='%23F8FAFC' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
    --form-bg: rgba(255, 255, 255, 0.1);
    --form-border: rgba(255, 255, 255, 0.2);
}

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

html, body {
    overscroll-behavior: none; /* Prevents pull-to-refresh & iOS rubber-band bounce */
}

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-gradient-start);
    background-image: 
        url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='500' height='500'%3E%3Ctext x='50' y='80' font-family='Outfit, sans-serif' font-weight='800' font-size='80' fill='rgba(79,70,229,0.04)' transform='rotate(-15 50 80)'%3E3%3C/text%3E%3Ctext x='350' y='120' font-family='Outfit, sans-serif' font-weight='800' font-size='120' fill='rgba(6,182,212,0.03)' transform='rotate(20 350 120)'%3E8%3C/text%3E%3Ctext x='150' y='350' font-family='Outfit, sans-serif' font-weight='800' font-size='100' fill='rgba(79,70,229,0.05)' transform='rotate(-10 150 350)'%3E1%3C/text%3E%3Ctext x='400' y='400' font-family='Outfit, sans-serif' font-weight='800' font-size='60' fill='rgba(6,182,212,0.04)' transform='rotate(15 400 400)'%3E5%3C/text%3E%3Ctext x='250' y='450' font-family='Outfit, sans-serif' font-weight='800' font-size='90' fill='rgba(79,70,229,0.03)' transform='rotate(-25 250 450)'%3E9%3C/text%3E%3Ctext x='30' y='250' font-family='Outfit, sans-serif' font-weight='800' font-size='65' fill='rgba(6,182,212,0.04)' transform='rotate(12 30 250)'%3E4%3C/text%3E%3Ctext x='450' y='60' font-family='Outfit, sans-serif' font-weight='800' font-size='75' fill='rgba(79,70,229,0.03)' transform='rotate(-8 450 60)'%3E7%3C/text%3E%3Ctext x='200' y='180' font-family='Outfit, sans-serif' font-weight='800' font-size='70' fill='rgba(6,182,212,0.05)' transform='rotate(25 200 180)'%3E2%3C/text%3E%3Ctext x='380' y='260' font-family='Outfit, sans-serif' font-weight='800' font-size='85' fill='rgba(79,70,229,0.04)' transform='rotate(-18 380 260)'%3E6%3C/text%3E%3C/svg%3E"),
        linear-gradient(135deg, var(--bg-gradient-start), var(--bg-gradient-end));
    color: var(--text-main);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    overflow-x: hidden;
    padding: 20px;
    
    /* Native App Feel Properties */
    touch-action: manipulation; /* Prevents double-tap zoom */
    -webkit-touch-callout: none; /* Prevents long-press copy popup on iOS */
    -webkit-user-select: none; /* Safari */
    user-select: none; /* Standard syntax */
}

/* Ensure inputs remain usable */
input, select, textarea {
    -webkit-user-select: auto;
    user-select: auto;
}

/* Glassmorphism Classes */
.glass {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--card-border);
    border-radius: 20px;
    box-shadow: 0 10px 40px -10px rgba(0, 0, 0, 0.1);
}

.theme-btn-minimal {
    background: transparent;
    border: 2px solid var(--text-muted);
    font-size: 1.3rem;
    cursor: pointer;
    transition: all 0.2s ease;
    padding: 6px 12px;
    border-radius: 10px;
    line-height: 1;
    user-select: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}
.theme-btn-minimal:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
}

.title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 2rem;
    background: -webkit-linear-gradient(45deg, var(--secondary), var(--primary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    text-align: center;
}

/* Container */
.container {
    width: 100%;
    max-width: 500px;
    padding: 30px;
    text-align: center;
    animation: fadeIn 0.5s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Buttons */
.btn {
    display: block;
    width: 100%;
    padding: 15px;
    margin-bottom: 15px;
    border: none;
    border-radius: 12px;
    font-size: 1.1rem;
    font-weight: 600;
    font-family: 'Outfit', sans-serif;
    color: white;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background: linear-gradient(90deg, var(--primary), #8E7CFF);
    box-shadow: 0 4px 15px rgba(108, 92, 231, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(108, 92, 231, 0.6);
}

.btn-secondary {
    background: linear-gradient(90deg, var(--secondary), #48dbfb);
    box-shadow: 0 4px 15px rgba(0, 206, 201, 0.4);
}

.btn-secondary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 206, 201, 0.6);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--text-muted);
    color: var(--text-muted);
}
.btn-outline:hover {
    color: var(--primary);
    border-color: var(--primary);
    background: rgba(79, 70, 229, 0.05);
}

/* Forms & Selects */
.input-group {
    margin-bottom: 20px;
    text-align: left;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 0.9rem;
    color: var(--text-muted);
}

.form-control {
    width: 100%;
    padding: 14px;
    background: var(--form-bg);
    border: 1px solid var(--form-border);
    border-radius: 10px;
    color: var(--text-main);
    font-family: 'Outfit', sans-serif;
    font-size: 1rem;
    outline: none;
}
.form-control:focus {
    border-color: var(--primary);
}

select.form-control {
    appearance: none;
    -webkit-appearance: none;
    background-image: var(--select-chevron);
    background-repeat: no-repeat;
    background-position: right 14px center;
    background-size: 16px;
}

select.form-control option {
    background: var(--option-bg);
    color: var(--text-main);
}

/* Sections */
.view-section {
    display: none;
    animation: fadeIn 0.4s ease;
}
.view-section.active {
    display: block;
}

/* Game Interface */
.game-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    width: 100%;
    max-width: 600px;
    margin-bottom: 20px;
}
.game-info {
    font-size: 1rem;
    color: var(--text-muted);
}
.room-badge {
    background: rgba(0,206,201, 0.2);
    color: var(--secondary);
    padding: 5px 12px;
    border-radius: 8px;
    font-weight: 600;
}

/* Sudoku Grid */
.sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, var(--cell-size));
    grid-template-rows: repeat(9, var(--cell-size));
    background: var(--cell-bg);
    border: 3px solid var(--grid-border);
    border-radius: 5px;
    width: fit-content;
    margin: 0 auto;
    overflow: hidden;
}

.sudoku-cell {
    position: relative;
    background: var(--cell-bg);
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary);
    cursor: pointer;
    user-select: none;
    transition: background 0.2s;
    /* Explicit borders to prevent subpixel scaling issues */
    border-right: 1px solid var(--cell-border);
    border-bottom: 1px solid var(--cell-border);
}

/* Styling the 3x3 blocks */
.sudoku-cell:nth-child(3n) { 
    border-right: 3px solid var(--grid-border); 
}
.sudoku-cell:nth-child(9n) { 
    border-right: none; 
}
.sudoku-cell:nth-child(n+19):nth-child(-n+27),
.sudoku-cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 3px solid var(--grid-border);
}
.sudoku-cell:nth-child(n+73):nth-child(-n+81) {
    border-bottom: none;
}

.sudoku-cell.fixed {
    color: var(--text-main);
    cursor: default;
    background: var(--cell-fixed-bg);
}

.sudoku-cell:hover:not(.fixed) {
    background: var(--cell-hover-bg);
}

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

.note-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0; left: 0;
    pointer-events: none;
}
.note-num {
    font-size: 0.65rem;
    font-weight: 500;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    justify-content: center;
    line-height: 1;
}

.mode-active {
    background: rgba(16, 185, 129, 0.1);
    box-shadow: inset 0 0 0 2px var(--success) !important;
    color: var(--success) !important;
}

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

.sudoku-cell.highlighted {
    background: var(--cell-highlight-bg);
}

.sudoku-cell.error {
    color: var(--danger);
    background: rgba(255, 118, 117, 0.1);
}

/* Opponent Progress Indicator - GREEN */
.sudoku-cell.opponent-solved {
    background: #D1FAE5 !important;
    color: #059669 !important;
}

/* Number Pad (Mobile Friendly) */
.numpad {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 10px;
    max-width: 600px;
    margin: 25px auto 0;
    width: 100%;
}
.numpad-btn {
    background: var(--card-bg);
    border: 1px solid var(--cell-border);
    color: var(--text-main);
    border-radius: 12px;
    padding: 15px 0;
    font-size: 1.5rem;
    font-family: inherit;
    font-weight: 600;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.numpad-btn:active:not(:disabled) {
    background: rgba(79, 70, 229, 0.1);
    transform: scale(0.95);
}

.numpad-btn:disabled {
    background: #F1F5F9;
    color: #94A3B8;
    cursor: not-allowed;
    border-color: #E2E8F0;
    box-shadow: none;
    opacity: 0.6;
}

/* Utilities */
.hidden { display: none !important; }
.text-center { text-align: center; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }

/* Status Bar */
.status-bar {
    display: flex;
    justify-content: space-between;
    width: 100%;
    max-width: 600px;
    margin: 10px auto;
    font-size: 0.9rem;
}
.player-score {
    padding: 8px 15px;
    border-radius: 20px;
    background: var(--card-bg);
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}
.player-score span {
    font-weight: 800;
}
.myself.player-score { border-left: 3px solid var(--primary); }
.error-score.player-score { border-left: 3px solid var(--danger); }
.opponent.player-score { border-left: 3px solid var(--success); }

/* Win Overlay */
.overlay {
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0,0,0,0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    backdrop-filter: blur(5px);
}
.overlay-content {
    background: var(--bg-gradient-start);
    padding: 40px;
    border-radius: 20px;
    text-align: center;
    border: 1px solid var(--primary);
    box-shadow: 0 0 30px rgba(108, 92, 231, 0.4);
}
.overlay-content h2 {
    font-size: 2.5rem;
    margin-bottom: 10px;
}
.overlay-content.win h2 { color: var(--success); }
.overlay-content.lose h2 { color: var(--danger); }

/* Responsive adjustments */
@media (max-width: 600px) {
    .sudoku-board {
        grid-template-columns: repeat(9, var(--cell-size-mobile));
        grid-template-rows: repeat(9, var(--cell-size-mobile));
    }
    .sudoku-cell {
        font-size: 1.2rem;
    }
    .title { font-size: 2.2rem; }
}

/* Active Room List Item Styling */
.room-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--form-bg);
    border: 1px solid var(--form-border);
    border-radius: 12px;
    margin-bottom: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    text-align: left;
}
.room-item:hover {
    background: rgba(79, 70, 229, 0.08);
    border-color: var(--primary);
    transform: translateY(-1px);
}
.room-item .room-code {
    font-weight: 800;
    letter-spacing: 1px;
    color: var(--primary);
}
.room-item .room-diff {
    font-size: 0.8rem;
    padding: 3px 8px;
    border-radius: 6px;
    background: rgba(0,0,0,0.05);
    color: var(--text-muted);
}
[data-theme="dark"] .room-item .room-diff {
    background: rgba(255,255,255,0.05);
}