:root {
    /* Color Variables and Design Tokens */
    --primary-gradient: linear-gradient(135deg, #FF9100 0%, #FF5E00 100%);
    --bg-body: #f2f2f7;
    --bg-card: #ffffff;
    --text-primary: #1c1c1e;
    --text-secondary: #8e8e93;
    --accent-green: #34c759;
    --accent-red: #ff3b30;
    --shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
    --radius: 24px;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}

/* Dark Mode Overrides */
body.dark-mode {
    --bg-body: #121212;
    --bg-card: #1e1e1e;
    --text-primary: #ffffff;
    --text-secondary: #a1a1aa;
    --shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
}

/* Global Reset and Base Styles */
* { margin: 0; padding: 0; box-sizing: border-box; -webkit-tap-highlight-color: transparent; }

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-body);
    color: var(--text-primary);
    min-height: 100vh;
    transition: background-color 0.3s ease, color 0.3s ease;
    padding-bottom: 90px; /* Space for bottom navigation bar */
}

/* --- RESPONSIVE LAYOUT (GRID SYSTEM) --- */
.container { 
    max-width: 1200px; /* Optimized for desktop support */
    margin: 0 auto; 
    padding: 20px; 
    display: grid;
    gap: 20px;
    /* Default Mobile Layout (Single Column) */
    grid-template-columns: 1fr;
    grid-template-areas: 
        "header"
        "balance"
        "actions"
        "transactions";
}

/* Header and User Greeting Styles */
.app-header {
    grid-area: header;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 10px;
}

.user-info h1 { font-size: 1.2rem; font-weight: 700; }
.user-info span { font-size: 0.9rem; color: var(--text-secondary); }

.header-actions { display: flex; gap: 15px; }
.icon-btn {
    background: var(--bg-card);
    border: none;
    width: 40px; height: 40px; border-radius: 50%;
    display: flex; align-items: center; justify-content: center;
    color: var(--text-primary); box-shadow: var(--shadow);
    cursor: pointer; transition: var(--transition);
}
.icon-btn:hover { transform: translateY(-2px); }

/* Balance Card Component with Gradient Background */
.balance-card {
    grid-area: balance;
    background: var(--primary-gradient);
    color: white;
    padding: 30px;
    border-radius: var(--radius);
    box-shadow: 0 10px 30px rgba(255, 94, 0, 0.3);
    position: relative;
    overflow: hidden;
    display: flex; flex-direction: column; justify-content: center;
}

/* Decorative radial gradient for the balance card */
.balance-card::before {
    content: ''; position: absolute; top: -50%; left: -50%; width: 200%; height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.2) 0%, transparent 60%); pointer-events: none;
}

.balance-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px; position: relative; z-index: 2; }
.balance-value { font-size: 2.2rem; font-weight: 700; margin-bottom: 20px; position: relative; z-index: 2; }
.balance-value.hidden { letter-spacing: 5px; filter: blur(4px); }
.card-footer { display: flex; gap: 10px; font-size: 0.85rem; opacity: 0.9; position: relative; z-index: 2; }

/* Quick Actions Section with Horizontal Scroll for Mobile */
.actions-section { grid-area: actions; }
.actions-section h3 { font-size: 1.1rem; margin-bottom: 15px; color: var(--text-primary); }

.actions-grid {
    display: flex;
    gap: 15px;
    overflow-x: auto;
    padding-bottom: 10px;
    scrollbar-width: none;
}
.actions-grid::-webkit-scrollbar { display: none; }

.action-item {
    display: flex; flex-direction: column; align-items: center;
    min-width: 80px; cursor: pointer; text-decoration: none;
    flex: 1; /* Distributed space for larger screens */
}

.action-icon {
    width: 60px; height: 60px; background-color: var(--bg-card);
    border-radius: 20px; display: flex; align-items: center; justify-content: center;
    font-size: 1.5rem; color: #FF5E00; margin-bottom: 8px;
    box-shadow: var(--shadow); transition: var(--transition);
}
.action-item:hover .action-icon { transform: scale(1.1) rotate(5deg); background-color: #fff0e6; }
.action-item span { font-size: 0.8rem; color: var(--text-secondary); font-weight: 500; text-align: center;}

/* Transactions List and Animation Effects */
.transactions-section { grid-area: transactions; }
.transactions-section h3 { display: flex; justify-content: space-between; align-items: center; margin-bottom: 15px; }
.view-all { font-size: 0.85rem; color: #FF5E00; text-decoration: none; }

.transaction-list { list-style: none; }
.transaction-item {
    background-color: var(--bg-card);
    padding: 18px; border-radius: 16px; margin-bottom: 12px;
    display: flex; justify-content: space-between; align-items: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.02);
    animation: slideIn 0.4s ease forwards; opacity: 0; transform: translateY(20px);
    transition: transform 0.2s;
}
.transaction-item:hover { transform: translateX(5px); } 

@keyframes slideIn { to { opacity: 1; transform: translateY(0); } }

.t-left { display: flex; gap: 15px; align-items: center; }
.t-icon {
    width: 45px; height: 45px; background-color: rgba(0,0,0,0.05);
    border-radius: 12px; display: flex; align-items: center; justify-content: center;
    font-size: 1.2rem; color: var(--text-secondary);
}
.t-info h4 { font-size: 1rem; color: var(--text-primary); font-weight: 600; margin-bottom: 2px; }
.t-info p { font-size: 0.8rem; color: var(--text-secondary); }
.t-amount { font-weight: 700; font-size: 1rem; }
.income { color: var(--accent-green); }
.expense { color: var(--accent-red); }

/* Sticky Bottom Navigation Bar with Blur Effect */
.bottom-nav {
    position: fixed; bottom: 20px; left: 50%; transform: translateX(-50%);
    width: 90%; max-width: 460px;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(15px); -webkit-backdrop-filter: blur(15px);
    border-radius: 20px; padding: 15px 30px;
    display: flex; justify-content: space-between;
    box-shadow: 0 10px 40px rgba(0,0,0,0.1); z-index: 100;
}
body.dark-mode .bottom-nav { background-color: rgba(30, 30, 30, 0.8); }
.nav-item { color: var(--text-secondary); font-size: 1.4rem; transition: var(--transition); position: relative; }
.nav-item.active { color: #FF5E00; transform: translateY(-5px); }
.nav-item.active::after {
    content: ''; position: absolute; bottom: -8px; left: 50%; transform: translateX(-50%);
    width: 5px; height: 5px; background: #FF5E00; border-radius: 50%;
}

/* Modal and Overlay System */
.modal-overlay {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%;
    background: rgba(0,0,0,0.6); backdrop-filter: blur(5px);
    z-index: 1000;
    display: flex; justify-content: center; align-items: flex-end; 
    opacity: 0; visibility: hidden; transition: var(--transition);
}
.modal-overlay.active { opacity: 1; visibility: visible; }

.modal-content {
    background: var(--bg-card); width: 100%; max-width: 500px;
    border-radius: 24px 24px 0 0; padding: 30px;
    transform: translateY(100%); transition: transform 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}
.modal-overlay.active .modal-content { transform: translateY(0); }

.modal-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; }
.close-modal { border: none; background: transparent; font-size: 1.5rem; color: var(--text-secondary); cursor: pointer; }
.input-group { margin-bottom: 20px; }
.input-group label { display: block; color: var(--text-secondary); margin-bottom: 8px; font-size: 0.9rem; }
.input-group input {
    width: 100%; padding: 16px; border-radius: 12px; border: 2px solid rgba(0,0,0,0.1);
    background: var(--bg-body); color: var(--text-primary); font-size: 1.1rem; outline: none; transition: 0.3s;
}
.input-group input:focus { border-color: #FF5E00; }
.btn-primary {
    width: 100%; padding: 18px; background: var(--primary-gradient); color: white; border: none; border-radius: 16px;
    font-size: 1rem; font-weight: 700; cursor: pointer; box-shadow: 0 4px 15px rgba(255, 94, 0, 0.3); transition: transform 0.1s;
}
.btn-primary:active { transform: scale(0.98); }

/* Success/Information Toast Notification */
.toast {
    position: fixed; top: 20px; left: 50%; transform: translateX(-50%) translateY(-100px);
    background: var(--text-primary); color: var(--bg-card); padding: 12px 24px; border-radius: 50px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.2); z-index: 2000; font-weight: 500; font-size: 0.9rem;
    display: flex; align-items: center; gap: 10px; transition: transform 0.5s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}
.toast.show { transform: translateX(-50%) translateY(0); }
.toast i { color: var(--accent-green); }


/* --- MEDIA QUERIES (RESPONSIVE BEHAVIOR) --- */

/* Tablets and Larger Screens (> 768px) */
@media (min-width: 768px) {
    .container {
        /* Switch to 2-column layout */
        grid-template-columns: 1fr 1fr;
        grid-template-areas: 
            "header header"
            "balance transactions"
            "actions transactions";
        align-items: start;
    }

    .balance-card {
        margin-bottom: 0;
        height: 100%; 
    }

    /* Actions grid adapts to a wrap layout instead of scroll */
    .actions-grid {
        flex-wrap: wrap; 
        justify-content: flex-start;
        overflow-x: visible;
    }
    
    .action-item {
        min-width: 100px;
        flex: 0 0 auto; 
    }

    /* Transactions list with internal scroll support */
    .transactions-section {
        background: var(--bg-card);
        padding: 20px;
        border-radius: var(--radius);
        box-shadow: var(--shadow);
        max-height: 600px; 
        overflow-y: auto; 
    }
    .transactions-section h3 { margin-top: 0; }
    .transaction-item { box-shadow: none; border: 1px solid rgba(0,0,0,0.05); }
}

/* Desktop Monitors (> 1024px) */
@media (min-width: 1024px) {
    .container {
        gap: 30px;
        grid-template-columns: 350px 1fr; /* Fixed sidebar, fluid main area */
    }

    /* Center-aligned Modal for Desktop */
    .modal-overlay { align-items: center; }
    .modal-content {
        border-radius: 24px;
        transform: scale(0.9);
        opacity: 0;
    }
    .modal-overlay.active .modal-content {
        transform: scale(1);
        opacity: 1;
    }

    /* Refined floating navigation for desktop */
    .bottom-nav {
        bottom: 30px;
        max-width: 400px;
        padding: 15px 40px;
        cursor: pointer;
    }
    .nav-item:hover { color: #FF5E00; transform: translateY(-3px); }
}