/* ===== CSS Variables ===== */
:root {
    /* Light Mode Colors */
    --bg-primary: #f0f4f8;
    --bg-secondary: #ffffff;
    --bg-card: rgba(255, 255, 255, 0.9);
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --accent-san: #3b82f6;
    --accent-pine: #ec4899;
    --accent-green: #10b981;
    --accent-orange: #f59e0b;
    --accent-red: #ef4444;
    --border-color: rgba(0, 0, 0, 0.1);
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
}

/* Dark Mode Colors */
[data-theme="dark"] {
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --bg-card: rgba(45, 55, 72, 0.9);
    --text-primary: #f7fafc;
    --text-secondary: #cbd5e0;
    --border-color: rgba(255, 255, 255, 0.1);
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.4);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background 0.3s ease, color 0.3s ease;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===== Theme Toggle ===== */
.theme-toggle {
    position: fixed;
    top: 1.5rem;
    right: 1.5rem;
    width: 55px;
    height: 55px;
    border-radius: 50%;
    border: none;
    background: linear-gradient(135deg, var(--accent-san) 0%, var(--accent-pine) 100%);
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    transition: transform 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle .moon-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .sun-icon {
    display: none;
}

[data-theme="dark"] .theme-toggle .moon-icon {
    display: inline;
}

/* ===== Header ===== */
.header {
    background: linear-gradient(135deg, var(--accent-san) 0%, var(--accent-pine) 100%);
    color: white;
    padding: var(--spacing-xl) 0 var(--spacing-lg);
    text-align: center;
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
}

.header h1 {
    font-size: clamp(2rem, 4vw, 2.5rem);
    font-weight: 800;
    margin-bottom: var(--spacing-xs);
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.95;
}

/* ===== Main Content ===== */
.main-content {
    padding-bottom: var(--spacing-xl);
}

section {
    margin-bottom: var(--spacing-xl);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.section-header h2 {
    font-size: 1.75rem;
    color: var(--text-primary);
}

/* ===== Summary Cards ===== */
.summary-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.summary-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    transition: transform 0.3s ease;
}

.summary-card:hover {
    transform: translateY(-5px);
}

.card-icon {
    font-size: 3rem;
}

.card-content h3 {
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.amount {
    font-size: 2rem;
    font-weight: 700;
    margin: 0;
}

.total-card .amount {
    color: var(--accent-san);
}

.paid-card .amount {
    color: var(--accent-green);
}

.pending-card .amount {
    color: var(--accent-orange);
}

/* ===== Contributions ===== */
.contributions-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.contributions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.contribution-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-lg);
    text-align: center;
    transition: transform 0.3s ease;
}

.contribution-card:hover {
    transform: translateY(-5px);
}

.person-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.person-icon {
    font-size: 2.5rem;
}

.person-header h3 {
    font-size: 1.5rem;
    font-weight: 700;
}

.san-card .person-header h3 {
    color: var(--accent-san);
}

.pine-card .person-header h3 {
    color: var(--accent-pine);
}

.contribution-amount {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-xs);
}

.san-card .contribution-amount {
    color: var(--accent-san);
}

.pine-card .contribution-amount {
    color: var(--accent-pine);
}

.contribution-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.progress-bar {
    width: 100%;
    height: 12px;
    background: var(--border-color);
    border-radius: 6px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    transition: width 0.3s ease;
    border-radius: 6px;
}

.san-progress {
    background: var(--accent-san);
}

.pine-progress {
    background: var(--accent-pine);
}

/* ===== Forms ===== */
.form-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow);
    margin-bottom: var(--spacing-md);
}

.form-card.hidden {
    display: none;
}

.form-card h3 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.875rem;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--accent-san);
}

.form-group input[readonly] {
    background: var(--bg-primary);
    cursor: not-allowed;
}

.radio-group {
    display: flex;
    gap: var(--spacing-md);
}

.radio-label {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    cursor: pointer;
    padding: 0.75rem var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--bg-secondary);
    transition: all 0.3s ease;
    flex: 1;
    justify-content: center;
}

.radio-label:hover {
    border-color: var(--accent-san);
}

.radio-label input[type="radio"] {
    width: auto;
    margin: 0;
}

.radio-label input[type="radio"]:checked + span {
    font-weight: 700;
}

.radio-label:has(input[type="radio"]:checked) {
    border-color: var(--accent-san);
    background: rgba(59, 130, 246, 0.1);
}

.form-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

/* ===== Buttons ===== */
.btn-primary,
.btn-secondary,
.btn-danger {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent-san) 0%, var(--accent-pine) 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-large {
    width: 100%;
    padding: 1rem;
    font-size: 1.1rem;
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    border-color: var(--accent-san);
}

.btn-danger {
    background: var(--accent-red);
    color: white;
}

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

/* ===== Operations List ===== */
.operations-list {
    display: grid;
    gap: var(--spacing-md);
}

.operation-card {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow);
    border-left: 4px solid var(--accent-san);
}

.operation-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
    gap: var(--spacing-sm);
}

.operation-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.operation-delete {
    background: var(--accent-red);
    color: white;
    border: none;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.875rem;
}

.operation-costs {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.cost-item {
    text-align: center;
    padding: var(--spacing-sm);
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
}

.cost-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.cost-value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.operation-progress {
    margin-top: var(--spacing-md);
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--spacing-xs);
    font-size: 0.875rem;
}

.progress-percentage {
    font-weight: 700;
    color: var(--accent-green);
}

.operation-progress .progress-bar {
    height: 20px;
    background: var(--border-color);
    border-radius: 10px;
    overflow: hidden;
}

.operation-progress .progress-fill {
    background: linear-gradient(135deg, var(--accent-green) 0%, #059669 100%);
}

/* ===== Payments History ===== */
.history-filters {
    display: flex;
    gap: var(--spacing-xs);
}

.filter-btn {
    padding: 0.5rem 1rem;
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.875rem;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--accent-san);
    color: white;
    border-color: var(--accent-san);
}

.payments-list {
    display: grid;
    gap: var(--spacing-sm);
}

.payment-item {
    background: var(--bg-card);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    box-shadow: var(--shadow);
    display: grid;
    grid-template-columns: auto 1fr auto auto;
    gap: var(--spacing-md);
    align-items: center;
    transition: transform 0.2s ease;
}

.payment-item:hover {
    transform: translateX(5px);
}

.payment-icon {
    font-size: 2rem;
}

.payment-info h4 {
    font-size: 1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.25rem;
}

.payment-meta {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.payment-amount {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--accent-green);
}

.payment-delete {
    background: var(--accent-red);
    color: white;
    border: none;
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 0.875rem;
}

.payment-item[data-payer="San"] {
    border-left: 4px solid var(--accent-san);
}

.payment-item[data-payer="Pine"] {
    border-left: 4px solid var(--accent-pine);
}

.empty-message {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* ===== Data Management ===== */
.data-actions {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-secondary);
    padding: var(--spacing-lg) 0;
    text-align: center;
    margin-top: var(--spacing-xl);
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .theme-toggle {
        top: 1rem;
        right: 1rem;
        width: 50px;
        height: 50px;
    }

    .header h1 {
        font-size: 1.75rem;
    }

    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .section-header h2 {
        font-size: 1.5rem;
    }

    .summary-section {
        grid-template-columns: 1fr;
    }

    .contributions-grid {
        grid-template-columns: 1fr;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .form-actions {
        flex-direction: column;
    }

    .form-actions button {
        width: 100%;
    }

    .payment-item {
        grid-template-columns: auto 1fr;
        gap: var(--spacing-sm);
    }

    .payment-amount {
        grid-column: 1 / -1;
        text-align: left;
        margin-top: var(--spacing-xs);
    }

    .payment-delete {
        grid-column: 1 / -1;
    }

    .data-actions {
        flex-direction: column;
    }

    .data-actions button {
        width: 100%;
    }

    .history-filters {
        width: 100%;
    }

    .filter-btn {
        flex: 1;
    }
}

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

.operation-card,
.payment-item {
    animation: fadeIn 0.3s ease;
}