* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-tap-highlight-color: transparent;
}

/* ================= THEME VARIABLES ================= */
:root {
    /* Light Theme (Default) */
    --primary: #4361ee;
    --secondary: #3f37c9;
    --accent: #4895ef;
    --success: #2ecc71;
    --dark: #1e293b;
    --light: #f8fafc;
    --gray: #64748b;
    --danger: #e74c3c;
    --warning: #f39c12;
    --info: #3498db;
    
    --gradient-bg: linear-gradient(135deg, #6a11cb 0%, #2575fc 100%);
    --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.95), rgba(255,255,255,0.85));
    
    /* Glassmorphism */
    --glass-header: rgba(255, 255, 255, 0.88);
    --glass-content: rgba(255, 255, 255, 0.8);
    --glass-card: rgba(255, 255, 255, 0.75);
    --glass-nav: rgba(255, 255, 255, 0.92);
    
    /* Borders & Shadows */
    --border-glass: rgba(255, 255, 255, 0.6);
    --border-subtle: rgba(0, 0, 0, 0.05);
    --border-input: rgba(0, 0, 0, 0.08);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.15);
    
    --transition-fast: all 0.25s cubic-bezier(0.165, 0.84, 0.44, 1);
    --transition: all 0.35s cubic-bezier(0.165, 0.84, 0.44, 1);
    --transition-slow: all 0.5s cubic-bezier(0.165, 0.84, 0.44, 1);
    
    --border-radius-sm: 12px;
    --border-radius: 16px;
    --border-radius-lg: 24px;
    --border-radius-full: 9999px;
    
    --safe-area-top: env(safe-area-inset-top);
    --safe-area-bottom: env(safe-area-inset-bottom);
    --safe-area-left: env(safe-area-inset-left);
    --safe-area-right: env(safe-area-inset-right);

    /* Modal Defaults (Light) */
    --modal-bg: #ffffff;
    --modal-text: #0f172a;
    --modal-subtext: #475569;
    --modal-indicator: #cbd5f5;
    --modal-close: #64748b;
    --modal-close-hover: #0f172a;
    --modal-btn-grad: linear-gradient(135deg, #1558B0, #2563eb);
    --modal-btn-sec-grad: linear-gradient(135deg, #6c757d, #495057);
}

/* ================= DARK THEME ================= */
.dark {
    --primary: #60a5fa;
    --secondary: #818cf8;
    --accent: #38bdf8;
    --success: #34d399;
    --dark: #f1f5f9;       /* Light text for readability */
    --light: #0f172a;      /* Dark background base */
    --gray: #94a3b8;
    --danger: #f87171;
    --warning: #fbbf24;
    --info: #38bdf8;
    
    /* Deep, rich dark gradient for the body background */
    --gradient-bg: linear-gradient(135deg, #020617 0%, #0f172a 100%);
    --gradient-card: linear-gradient(
        145deg,
        rgba(15,23,42,.95),
        rgba(2,6,23,.95)
    );
    
    /* Dark glassmorphism */
    
    --glass-nav: rgba(15, 23, 42, 0.9);
    --glass-content: rgba(15,23,42,.9);
    --glass-card: rgba(15,23,42,.85);
    --glass-header: rgba(2,6,23,.9);

    
    --border-glass: rgba(148, 163, 184, 0.15);
    --border-subtle: rgba(255, 255, 255, 0.08);
    --border-input: rgba(255, 255, 255, 0.1);
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.5);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.6);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.7);

    /* Modal Dark Overrides */
    --modal-bg: #0f172a;
    --modal-text: #f8fafc;
    --modal-subtext: #94a3b8;
    --modal-indicator: #334155;
    --modal-close: #64748b;
    --modal-close-hover: #f8fafc;
    --modal-btn-grad: linear-gradient(135deg, #2563eb, #1d4ed8);
    --modal-btn-sec-grad: linear-gradient(135deg, #475569, #334155);
}

/* Auto-detect system preference (optional) */
@media (prefers-color-scheme: dark) {
    :root:not(.light) {
        --primary: #60a5fa; --secondary: #818cf8; --accent: #38bdf8; --success: #34d399;
        --dark: #f1f5f9; --light: #0f172a; --gray: #94a3b8; --danger: #f87171; --warning: #fbbf24; --info: #38bdf8;
        --gradient-bg: linear-gradient(135deg, #020617 0%, #0f172a 100%);
        --gradient-card: linear-gradient(145deg, rgba(30, 41, 59, 0.8), rgba(15, 23, 42, 0.6));
        --glass-header: rgba(15, 23, 42, 0.85); --glass-content: rgba(30, 41, 59, 0.7);
        --glass-card: rgba(30, 41, 59, 0.6); --glass-nav: rgba(15, 23, 42, 0.9);
        --border-glass: rgba(148, 163, 184, 0.15); --border-subtle: rgba(255, 255, 255, 0.08); --border-input: rgba(255, 255, 255, 0.1);
        --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.5); --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.6); --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.7);
        --modal-bg: #0f172a; --modal-text: #f8fafc; --modal-subtext: #94a3b8; --modal-indicator: #334155;
        --modal-close: #64748b; --modal-close-hover: #f8fafc; --modal-btn-grad: linear-gradient(135deg, #2563eb, #1d4ed8); --modal-btn-sec-grad: linear-gradient(135deg, #475569, #334155);
    }
}

/* ================= BASE STYLES ================= */
body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--gradient-bg);
    color: var(--dark);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
    overflow-x: hidden;
    overscroll-behavior-y: contain;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    padding-bottom: calc(var(--safe-area-bottom) + 70px);
    padding-top: var(--safe-area-top);
    background-attachment: fixed;
    transition: background 0.4s ease, color 0.4s ease;
}

body::before {
    content: '';
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.08) 0%, rgba(255,255,255,0) 70%);
    z-index: -1;
    animation: rotate 35s linear infinite;
    pointer-events: none;
    transition: background 0.4s ease;
}

.dark body::before {
    background: radial-gradient(circle, rgba(96, 165, 250, 0.05) 0%, rgba(255,255,255,0) 70%);
}


body.dark {
    background: linear-gradient(135deg, #020617 0%, #0f172a 100%) !important;
}

.dark body,
body.dark {
    background-color: #020617 !important;
    background-image: linear-gradient(
        135deg,
        #020617 0%,
        #0f172a 100%
    ) !important;
}

@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

/* ================= HEADER ================= */
.dashboard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: calc(12px + var(--safe-area-top)) 16px 12px;
    background: var(--glass-header);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    height: calc(60px + var(--safe-area-top));
    border-bottom-left-radius: 20px;
    border-bottom-right-radius: 20px;
    margin-bottom: 24px;
    transition: var(--transition);
}

.dashboard-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--primary), var(--accent));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.icon-btn {
    width: 40px;
    height: 40px;
    border-radius: var(--border-radius-full);
    background: var(--glass-card);
    border: none;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: var(--transition-fast);
    position: relative;
    box-shadow: var(--shadow-sm);
    color: var(--gray);
    flex-shrink: 0;
}

.icon-btn:active {
    transform: scale(0.95);
    background: var(--glass-content);
}

.icon-btn:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(67, 97, 238, 0.4);
}

.icon-btn svg {
    width: 20px;
    height: 20px;
    fill: currentColor;
    transition: var(--transition-fast);
}

/* ================= MAIN CONTENT ================= */
.dashboard {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: 0 16px;
    max-width: 100%;
    margin: 0 auto;
    width: 100%;
    position: relative;
    z-index: 10;
}

.content {
    background: var(--gradient-card);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-lg);
    padding: 28px 24px;
    position: relative;
    overflow: hidden;
    margin-bottom: 20px;
    border: 1px solid var(--border-glass);
    transition: var(--transition);
}

.content::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(67, 97, 238, 0.03) 0%, rgba(255,255,255,0) 70%);
    z-index: -1;
    animation: rotate 45s linear infinite reverse;
}

/* ================= TOP ACTIONS & BUTTONS ================= */
.top-actions {
    margin-bottom: 24px;
}

.btn {
    width: 100%;
    padding: 14px 20px;
    border-radius: var(--border-radius-full);
    font-family: 'Inter', sans-serif;
    font-weight: 600;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    text-decoration: none;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    border: none;
    cursor: pointer;
    box-shadow: var(--shadow-md);
    line-height: 1.3;
}

.btn.primary {
    background: var(--gradient-bg);
    color: white;
    box-shadow: 0 4px 15px rgba(67, 97, 238, 0.4);
}

.btn.secondary {
    background: var(--glass-card);
    color: var(--primary);
    border: 1px solid var(--border-input);
    box-shadow: var(--shadow-sm);
}

.btn:active {
    transform: scale(0.98);
}

.btn svg {
    width: 22px;
    height: 22px;
    fill: currentColor;
}

.btn::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
    transition: left 0.7s;
}

.btn:hover::after {
    left: 100%;
}

.btn.primary:hover {
    box-shadow: 0 6px 20px rgba(67, 97, 238, 0.5);
}

.btn.secondary:hover {
    background: var(--glass-content);
    transform: translateY(-1px);
}

.btn:disabled {
    opacity: 0.7;
    cursor: not-allowed;
    transform: none;
}

/* ================= INVOICE FILTERS ================= */
.invoice-filters {
    display: flex;
    gap: 8px;
    margin-bottom: 28px;
    overflow-x: auto;
    padding-bottom: 8px;
    -ms-overflow-style: none;
    scrollbar-width: none;
}

.invoice-filters::-webkit-scrollbar {
    display: none;
}

.filter {
    padding: 8px 16px;
    border-radius: var(--border-radius-full);
    background: var(--glass-card);
    border: 1px solid var(--border-input);
    color: var(--gray);
    font-family: 'Inter', sans-serif;
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition-fast);
    white-space: nowrap;
    flex-shrink: 0;
}

.filter:hover {
    background: rgba(67, 97, 238, 0.1);
    color: var(--primary);
}

.filter.active {
    background: var(--primary);
    color: white;
    box-shadow: 0 4px 12px rgba(67, 97, 238, 0.3);
}

/* ================= INVOICES GRID ================= */
.invoices-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
}

.invoice-card {
    background: var(--glass-card);
    border-radius: var(--border-radius);
    padding: 20px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-subtle);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    opacity: 0;
    transform: translateY(20px);
}

.invoice-card.visible {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 0.4s ease, transform 0.4s ease;
}

.invoice-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    background: var(--glass-content);
}

.invoice-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 16px;
}

.invoice-id {
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--dark);
    margin-bottom: 4px;
}

.invoice-date {
    color: var(--gray);
    font-size: 0.9rem;
}

.status {
    padding: 4px 12px;
    border-radius: var(--border-radius-full);
    font-weight: 600;
    font-size: 0.85rem;
    letter-spacing: 0.5px;
}

.status.paid {
    background: rgba(46, 204, 113, 0.1);
    color: var(--success);
}

.status.pending {
    background: rgba(243, 156, 18, 0.1);
    color: var(--warning);
}

.status.unpaid,
.status.overdue {
    background: rgba(231, 76, 60, 0.1);
    color: var(--danger);
}

.invoice-body {
    margin-bottom: 16px;
}

.invoice-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
    font-size: 0.95rem;
}

.invoice-row:last-child {
    margin-bottom: 0;
}

.invoice-amount {
    font-weight: 700;
    font-family: 'Inter', sans-serif;
}

.invoice-amount.paid {
    color: var(--success);
}

.invoice-amount.pending,
.invoice-amount.unpaid {
    color: var(--warning);
}

.invoice-amount.overdue {
    color: var(--danger);
}

.invoice-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 16px;
    border-top: 1px solid var(--border-subtle);
    color: var(--primary);
    font-weight: 500;
    font-size: 0.95rem;
    cursor: pointer;
    transition: var(--transition-fast);
}

.invoice-footer:hover {
    color: var(--accent);
}

.invoice-footer svg {
    width: 16px;
    height: 16px;
    fill: currentColor;
    transition: var(--transition-fast);
}

.invoice-footer:hover svg {
    transform: translateX(3px);
}

/* Action buttons for mobile */
.invoice-actions {
    display: flex;
    gap: 8px;
    margin-top: 12px;
    justify-content: flex-end;
}

.action-btn {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: var(--transition-fast);
    border: 1px solid var(--border-input);
    background: var(--glass-card);
    color: var(--gray);
}

.action-btn:hover {
    background: rgba(67, 97, 238, 0.1);
    color: var(--primary);
    transform: translateY(-1px);
    box-shadow: var(--shadow-sm);
}

.action-btn.edit:hover {
    background: rgba(52, 152, 219, 0.1);
    color: var(--info);
}

.action-btn.delete:hover {
    background: rgba(231, 76, 60, 0.1);
    color: var(--danger);
}

.action-btn svg {
    width: 18px;
    height: 18px;
    fill: currentColor;
}

/* ================= BOTTOM NAVIGATION ================= */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--glass-nav);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    display: flex;
    justify-content: space-around;
    padding: 10px 8px calc(10px + var(--safe-area-bottom)) 8px;
    box-shadow: 0 -2px 20px rgba(0, 0, 0, 0.12);
    z-index: 200;
    border-top-left-radius: 24px;
    border-top-right-radius: 24px;
    max-width: 600px;
    margin: 0 auto;
    width: 100%;
    left: 50%;
    transform: translateX(-50%);
    transition: var(--transition);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 4px;
    color: var(--gray);
    text-decoration: none;
    font-size: 0.75rem;
    font-weight: 500;
    padding: 8px 4px;
    position: relative;
    transition: var(--transition-fast);
    width: 100%;
    max-width: 80px;
    border-radius: var(--border-radius-sm);
}

.nav-item.active {
    color: var(--primary);
    background: rgba(67, 97, 238, 0.08);
    transform: translateY(-2px);
}

.nav-item.active::after {
    content: '';
    position: absolute;
    bottom: -6px;
    width: 28px;
    height: 4px;
    background: var(--primary);
    border-radius: 2px;
}

.nav-item svg {
    width: 24px;
    height: 24px;
    fill: currentColor;
    transition: var(--transition-fast);
}

.nav-item:hover svg, 
.nav-item.active svg {
    transform: scale(1.15);
}

.nav-item.active svg {
    fill: var(--primary);
}

/* ================= PARTICLES & ANIMATIONS ================= */
.particles {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: -1;
}

.particle {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.6);
    animation: float 15s infinite linear;
}

@keyframes float {
    0% {
        transform: translateY(0) translateX(0) rotate(0deg);
        opacity: 1;
    }
    100% {
        transform: translateY(-100vh) translateX(100px) rotate(720deg);
        opacity: 0;
    }
}

@keyframes haptic {
    0% { transform: translateX(0); }
    25% { transform: translateX(-2px); }
    50% { transform: translateX(2px); }
    75% { transform: translateX(-2px); }
    100% { transform: translateX(0); }
}

.haptic-feedback {
    animation: haptic 0.15s ease-in-out;
}

/* ================= MODAL OVERLAY ================= */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(2, 6, 23, 0.6);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: flex-end;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.3s ease;
    z-index: 9999;
}

.modal-overlay.show {
    opacity: 1;
    pointer-events: auto;
}

.modal-card {
    background: var(--modal-bg);
    border-radius: 14px;
    padding: 32px 28px;
    width: 100%;
    max-width: 420px;
    text-align: center;
    box-shadow: 0 -10px 40px rgba(0, 0, 0, 0.15);
    transform: translateY(100%);
    opacity: 1;
    transition: transform 0.35s cubic-bezier(0.16, 1, 0.3, 1);
    color: var(--modal-text);
}

.modal-overlay.show .modal-card {
    transform: translateY(0);
}

.modal-card::before {
    content: "";
    width: 42px;
    height: 4px;
    background: var(--modal-indicator);
    border-radius: 999px;
    display: block;
    margin: 0 auto 18px;
}

.modal-icon {
    width: 58px;
    height: 58px;
    margin: 4px auto 16px;
    color: var(--success);
    animation: popIcon 0.4s ease-out;
}

.modal-icon.error {
    color: var(--danger);
}

.modal-icon svg {
    width: 100%;
    height: 100%;
}

.modal-card h2 {
    font-size: 20px;
    font-weight: 600;
    color: var(--modal-text);
    margin-bottom: 8px;
}

.modal-card p {
    font-size: 14.5px;
    line-height: 1.6;
    color: var(--modal-subtext);
    margin-bottom: 22px;
}

.modal-buttons {
    display: flex;
    gap: 12px;
    margin-top: 16px;
}

.modal-btn {
    flex: 1;
    padding: 14px;
    font-size: 15px;
    font-weight: 600;
    border-radius: 14px;
    border: none;
    background: var(--modal-btn-grad);
    color: #fff;
    cursor: pointer;
    transition: transform 0.12s ease, box-shadow 0.2s ease;
}

.modal-btn.secondary {
    background: var(--modal-btn-sec-grad);
}

.modal-btn:active {
    transform: scale(0.97);
    box-shadow: 0 10px 25px rgba(21, 88, 176, 0.35);
}

.close {
    position: absolute;
    top: 14px;
    right: 18px;
    font-size: 1.3rem;
    color: var(--modal-close);
    cursor: pointer;
    transition: color 0.2s ease;
}

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

/* ================= RESPONSIVE DESIGN ================= */
@media (min-width: 768px) {
    .dashboard-header {
        height: calc(72px + var(--safe-area-top));
        padding: calc(16px + var(--safe-area-top)) 24px 16px;
        border-radius: 0 0 28px 28px;
        margin-bottom: 28px;
    }
    
    .dashboard-header h2 {
        font-size: 1.75rem;
    }
    
    .content {
        padding: 32px 28px;
        border-radius: var(--border-radius-lg);
    }
    
    .btn {
        padding: 16px 24px;
        font-size: 1.15rem;
    }
    
    .btn svg {
        width: 24px;
        height: 24px;
    }
    
    .invoice-filters {
        gap: 12px;
    }
    
    .filter {
        padding: 10px 20px;
        font-size: 0.95rem;
    }
    
    .invoices-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
    }
    
    .invoice-card {
        padding: 24px;
    }
    
    .invoice-id {
        font-size: 1.2rem;
    }
    
    .action-btn {
        width: 40px;
        height: 40px;
    }
    
    .action-btn svg {
        width: 20px;
        height: 20px;
    }
    
    .bottom-nav {
        max-width: 1200px;
        border-radius: 28px;
        padding: 8px 16px calc(8px + var(--safe-area-bottom)) 16px;
        bottom: auto;
        top: auto;
        left: 0;
        right: 0;
        transform: none;
        width: 100%;
        margin: 0 auto;
        position: sticky;
    }
    
    .nav-item {
        flex-direction: row;
        justify-content: center;
        gap: 8px;
        font-size: 0.9rem;
        padding: 10px 12px;
        max-width: none;
        border-radius: var(--border-radius);
    }
    
    .nav-item.active::after {
        display: none;
    }
    
    .nav-item.active {
        transform: none;
        background: rgba(67, 97, 238, 0.15);
    }
}

@media (min-width: 1024px) {
    .content {
        padding: 40px 36px;
    }
    
    .invoices-grid {
        grid-template-columns: repeat(3, 1fr);
        gap: 24px;
    }
    
    .invoice-card {
        padding: 28px;
    }
    
    .invoice-id {
        font-size: 1.3rem;
    }
}