/* ============================================
   BASE STYLES & VARIABLES
   ============================================ */

:root {
    /* Colors - Light Mode */
    --color-primary: #4a6fa5;
    --color-primary-light: #f0f4f8;
    --color-primary-hover: #3d5a7f;
    
    --color-bg-main: #ffffff;
    --color-bg-secondary: #f8f9fa;
    --color-text-primary: #2c3e50;
    --color-text-secondary: #666666;
    --color-text-light: #999999;
    
    --color-border: #e0e0e0;
    --color-border-light: #eeeeee;
    
    --color-success: #27ae60;
    --color-warning: #f39c12;
    --color-danger: #e74c3c;
    --color-info: #3498db;
    
    --color-input-bg: #ffffff;
    --color-input-border: #d0d0d0;
    --color-input-focus: #4a6fa5;
    
    /* Dark Mode */
    --color-dark-bg-main: #1a1a1a;
    --color-dark-bg-secondary: #242424;
    --color-dark-text-primary: #e0e0e0;
    --color-dark-text-secondary: #a0a0a0;
    --color-dark-text-light: #707070;
    --color-dark-border: #404040;
    --color-dark-border-light: #303030;
    --color-dark-input-bg: #2a2a2a;
    --color-dark-input-border: #404040;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    
    /* Typography */
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* Dark Mode */
body.dark-mode {
    --color-bg-main: var(--color-dark-bg-main);
    --color-bg-secondary: var(--color-dark-bg-secondary);
    --color-text-primary: var(--color-dark-text-primary);
    --color-text-secondary: var(--color-dark-text-secondary);
    --color-text-light: var(--color-dark-text-light);
    --color-border: var(--color-dark-border);
    --color-border-light: var(--color-dark-border-light);
    --color-input-bg: var(--color-dark-input-bg);
    --color-input-border: var(--color-dark-input-border);
    --color-primary-light: #2a3a4a;
}

/* ============================================
   GLOBAL STYLES
   ============================================ */

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background-color: var(--color-bg-secondary);
    color: var(--color-text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-base), color var(--transition-base);
}

/* ============================================
   LAYOUT & CONTAINER
   ============================================ */

.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.section {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-light);
}

.section-content {
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.section-header {
    margin-bottom: var(--spacing-md);
}

.section-header h2 {
    font-size: var(--font-size-xl);
    color: var(--color-text-primary);
    font-weight: 600;
}

/* ============================================
   HEADER
   ============================================ */

.header {
    background-color: var(--color-bg-main);
    border-bottom: 2px solid var(--color-primary);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-left h1 {
    font-size: var(--font-size-2xl);
    color: var(--color-primary);
    margin-bottom: 0.25rem;
    font-weight: 700;
}

.header-left .tagline {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.header-right {
    display: flex;
    gap: var(--spacing-sm);
    align-items: center;
}

/* ============================================
   THEME TOGGLE
   ============================================ */

.theme-toggle {
    width: 40px;
    height: 40px;
    border: 1px solid var(--color-border);
    background-color: var(--color-bg-main);
    border-radius: var(--radius-md);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-fast), border-color var(--transition-fast);
    padding: 0;
}

.theme-toggle:hover {
    background-color: var(--color-primary-light);
    border-color: var(--color-primary);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
    color: var(--color-text-primary);
    stroke: currentColor;
}

.theme-toggle .icon-sun {
    display: block;
}

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

body.dark-mode .theme-toggle .icon-sun {
    display: none;
}

body.dark-mode .theme-toggle .icon-moon {
    display: block;
}

/* ============================================
   PROGRAM SELECTOR
   ============================================ */

.program-selector-section {
    background-color: var(--color-bg-main);
}

.program-selector-section .section-content {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.label {
    font-weight: 600;
    color: var(--color-text-primary);
    font-size: var(--font-size-base);
    white-space: nowrap;
}

.program-select {
    flex: 1;
    padding: 0.75rem var(--spacing-sm);
    border: 1px solid var(--color-input-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    background-color: var(--color-input-bg);
    color: var(--color-text-primary);
    cursor: pointer;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.program-select:hover {
    border-color: var(--color-primary);
}

.program-select:focus {
    outline: none;
    border-color: var(--color-input-focus);
    box-shadow: 0 0 0 3px rgba(74, 111, 165, 0.1);
}

/* ============================================
   METRICS DASHBOARD
   ============================================ */

.metrics-section {
    background-color: var(--color-bg-main);
}

.metrics-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
}

.metric-card {
    background-color: var(--color-bg-secondary);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    text-align: center;
    transition: box-shadow var(--transition-base), transform var(--transition-base);
    min-height: 150px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.metric-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.metric-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.metric-value {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    color: var(--color-primary);
    margin: var(--spacing-sm) 0;
}

.metric-info {
    font-size: var(--font-size-sm);
    color: var(--color-text-light);
}

/* Progress Bar */
.progress-bar {
    width: 100%;
    height: 6px;
    background-color: var(--color-border-light);
    border-radius: 3px;
    overflow: hidden;
    margin: var(--spacing-sm) 0;
}

.progress-fill {
    height: 100%;
    background-color: var(--color-primary);
    border-radius: 3px;
    transition: width var(--transition-base);
}

/* ============================================
   GRADING SCALE SECTION
   ============================================ */

.grading-section {
    background-color: var(--color-bg-main);
}

.grading-table-wrapper {
    max-width: 600px;
    margin: 0 auto;
    overflow-x: auto;
}

.grading-table {
    width: 100%;
    border-collapse: collapse;
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-lg);
    overflow: hidden;
}

.grading-table thead {
    background-color: var(--color-primary);
    color: #ffffff;
}

.grading-table th {
    padding: 1rem;
    text-align: center;
    font-weight: 600;
    font-size: var(--font-size-sm);
    letter-spacing: 0.5px;
}

.grading-table td {
    padding: 0.875rem 1rem;
    text-align: center;
    border-bottom: 1px solid var(--color-border-light);
    font-size: var(--font-size-sm);
    color: var(--color-text-primary);
}

.grading-table tbody tr {
    transition: background-color var(--transition-fast);
}

.grading-table tbody tr:hover {
    background-color: var(--color-bg-secondary);
}

.grading-table tbody tr:last-child {
    border-bottom: none;
}

/* Grade Badges */
.grade-badge {
    display: inline-block;
    min-width: 40px;
    padding: 0.4rem 0.6rem;
    border-radius: 4px;
    font-weight: 600;
    font-size: 0.85rem;
    color: #ffffff;
}

.grade-a-plus {
    background-color: #10b981;
}

.grade-a {
    background-color: #14b8a6;
}

.grade-a-minus {
    background-color: #06b6d4;
}

.grade-b-plus {
    background-color: #3b82f6;
}

.grade-b {
    background-color: #8b5cf6;
}

.grade-b-minus {
    background-color: #a855f7;
}

.grade-c-plus {
    background-color: #f59e0b;
}

.grade-c {
    background-color: #f97316;
}

.grade-c-minus {
    background-color: #ef4444;
}

.grade-f {
    background-color: #dc2626;
}

.gpa-value {
    font-weight: 600;
    color: var(--color-primary);
}

.grade-fail {
    background-color: rgba(220, 38, 38, 0.05);
}

body.dark-mode .grade-fail {
    background-color: rgba(220, 38, 38, 0.1);
}

/* ============================================
   AUTOCOMPLETE
   ============================================ */

.autocomplete-wrapper {
    flex: 1;
    min-width: 200px;
    position: relative;
}

.autocomplete-suggestions {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-bg-main);
    border: 1px solid var(--color-input-border);
    border-top: none;
    border-radius: 0 0 var(--radius-md) var(--radius-md);
    max-height: 300px;
    overflow-y: auto;
    z-index: 1000;
    display: none;
    box-shadow: var(--shadow-md);
}

.autocomplete-suggestions.show {
    display: block;
}

.autocomplete-item {
    padding: var(--spacing-sm) var(--spacing-md);
    cursor: pointer;
    transition: background-color var(--transition-fast);
    border-bottom: 1px solid var(--color-border-light);
    font-size: var(--font-size-sm);
}

.autocomplete-item:last-child {
    border-bottom: none;
}

.autocomplete-item:hover,
.autocomplete-item.highlighted {
    background-color: var(--color-primary-light);
}

.autocomplete-item-code {
    font-weight: 600;
    color: var(--color-primary);
    display: block;
}

.autocomplete-item-name {
    font-size: var(--font-size-xs);
    color: var(--color-text-secondary);
    margin-top: 0.25rem;
}

/* ============================================
   CALCULATOR SECTION
   ============================================ */

.calculator-section {
    background-color: var(--color-bg-main);
}

.calculator-controls {
    max-width: 1200px;
    margin: 0 auto;
    margin-bottom: var(--spacing-lg);
}

.input-group {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.input-field {
    flex: 1;
    min-width: 200px;
    padding: 0.75rem var(--spacing-sm);
    border: 1px solid var(--color-input-border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    background-color: var(--color-input-bg);
    color: var(--color-text-primary);
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.input-field:focus {
    outline: none;
    border-color: var(--color-input-focus);
    box-shadow: 0 0 0 3px rgba(74, 111, 165, 0.1);
}

.input-field::placeholder {
    color: var(--color-text-light);
}

#courseMarksInput {
    min-width: 140px;
    flex: 0 1 140px;
    max-width: 140px;
}

/* Buttons */
.btn-primary {
    padding: 0.75rem var(--spacing-md);
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
    white-space: nowrap;
}

.btn-primary:hover {
    background-color: var(--color-primary-hover);
    transform: translateY(-1px);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-danger {
    padding: 0.5rem var(--spacing-sm);
    background-color: var(--color-danger);
    color: white;
    border: none;
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: background-color var(--transition-fast);
}

.btn-danger:hover {
    background-color: #c0392b;
}

.btn-danger-secondary {
    padding: 0.75rem var(--spacing-md);
    background-color: var(--color-danger);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
    white-space: nowrap;
}

.btn-danger-secondary:hover {
    background-color: #c0392b;
    transform: translateY(-1px);
}

.btn-danger-secondary:active {
    transform: translateY(0);
}

.action-buttons {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    justify-content: flex-end;
}

/* Courses Table */
.courses-table-wrapper {
    max-width: 1200px;
    margin: 0 auto;
    background-color: var(--color-bg-secondary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    border: 1px solid var(--color-border-light);
}

.courses-table {
    width: 100%;
    border-collapse: collapse;
    font-size: var(--font-size-sm);
}

.courses-table thead {
    background-color: var(--color-primary);
    color: white;
}

.courses-table th {
    padding: var(--spacing-sm) var(--spacing-md);
    text-align: left;
    font-weight: 600;
}

.courses-table td {
    padding: var(--spacing-sm) var(--spacing-md);
    border-bottom: 1px solid var(--color-border-light);
    color: var(--color-text-primary);
}

.courses-table tbody tr:hover {
    background-color: var(--color-primary-light);
}

.courses-table input[type="number"] {
    width: 80px;
    padding: 0.4rem var(--spacing-xs);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    background-color: var(--color-input-bg);
    color: var(--color-text-primary);
    font-size: var(--font-size-sm);
}

.courses-table input[type="number"]:focus {
    outline: none;
    border-color: var(--color-primary);
}

.empty-row {
    text-align: center;
    color: var(--color-text-secondary);
}

.empty-row td {
    padding: var(--spacing-lg) var(--spacing-md);
}

/* Semester Summary */
.semester-summary {
    max-width: 1200px;
    margin: var(--spacing-lg) auto 0;
    padding: var(--spacing-md);
    background-color: var(--color-primary-light);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border-light);
}

.summary-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid rgba(74, 111, 165, 0.1);
}

.summary-row:last-child {
    border-bottom: none;
}

.summary-label {
    font-weight: 600;
    color: var(--color-text-primary);
}

.summary-value {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--color-primary);
}

.summary-row.semester-gpa .summary-value {
    font-size: var(--font-size-xl);
}

/* ============================================
   FOOTER
   ============================================ */

.footer {
    margin-top: 4rem;
    padding: 3rem 2rem 2rem;
    background-color: #ffffff;
    transition: background-color 0.3s ease;
}

body.dark-mode .footer {
    background-color: #1f2937;
}

.footer-content {
    max-width: 700px;
    margin: 0 auto;
    text-align: center;
}

/* Contribute Card */
.contribute-card {
    background-color: #f9fafb;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    padding: 2rem;
    margin-bottom: 3rem;
}

body.dark-mode .contribute-card {
    background-color: #111827;
    border-color: #374151;
}

.contribute-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: #374151;
    margin: 0 0 0.5rem 0;
}

body.dark-mode .contribute-title {
    color: #f3f4f6;
}

.contribute-subtitle {
    font-size: 0.9rem;
    color: #6b7280;
    margin: 0 0 1.5rem 0;
    line-height: 1.5;
}

body.dark-mode .contribute-subtitle {
    color: #d1d5db;
}

/* Contribute Buttons */
.contribute-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.btn-outline {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border: 1.5px solid #d1d5db;
    border-radius: 6px;
    color: #374151;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s ease;
    cursor: pointer;
    background-color: #ffffff;
}

.btn-outline:hover {
    border-color: #4a6fa5;
    color: #4a6fa5;
    background-color: #f0f4f9;
}

body.dark-mode .btn-outline {
    background-color: #1f2937;
    color: #e5e7eb;
    border-color: #4b5563;
}

body.dark-mode .btn-outline:hover {
    border-color: #93c5fd;
    color: #93c5fd;
    background-color: #0f172a;
}

/* Divider */
.footer-divider {
    width: 100%;
    height: 1px;
    background-color: #e5e7eb;
    margin: 3rem 0;
}

body.dark-mode .footer-divider {
    background-color: #374151;
}

/* Creator Credit */
.footer-credit {
    font-size: 0.95rem;
    color: #374151;
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

body.dark-mode .footer-credit {
    color: #e5e7eb;
}

.creator-name {
    font-weight: 600;
    color: #4a6fa5;
}

body.dark-mode .creator-name {
    color: #93c5fd;
}

/* Footer Icons */
.footer-icons {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    margin-bottom: 2rem;
}

.footer-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    color: #6b7280;
    text-decoration: none;
    transition: color 0.2s ease, background-color 0.2s ease;
    border-radius: 6px;
}

.footer-icon:hover {
    color: #4a6fa5;
    background-color: #f3f4f6;
}

body.dark-mode .footer-icon {
    color: #9ca3af;
}

body.dark-mode .footer-icon:hover {
    color: #93c5fd;
    background-color: #374151;
}

/* Footer Notice */
.footer-notice {
    font-size: 0.8rem;
    color: #9ca3af;
    line-height: 1.5;
    max-width: 500px;
    margin: 0 auto;
}

body.dark-mode .footer-notice {
    color: #6b7280;
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }

    .header-left h1 {
        font-size: var(--font-size-xl);
    }

    .section {
        padding: var(--spacing-md);
    }

    .program-selector-section .section-content {
        flex-direction: column;
        align-items: stretch;
    }

    .program-select {
        flex: 1;
    }

    .metrics-grid {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
        gap: var(--spacing-sm);
    }

    .metric-card {
        min-height: 120px;
        padding: var(--spacing-sm);
    }

    .metric-value {
        font-size: var(--font-size-xl);
    }

    .input-group {
        flex-direction: column;
    }

    #courseMarksInput {
        min-width: 100%;
        flex: 1;
        max-width: none;
    }

    .input-field {
        min-width: 100%;
    }

    .action-buttons {
        flex-direction: column;
    }

    .btn-danger-secondary {
        width: 100%;
    }

    .courses-table {
        font-size: var(--font-size-xs);
    }

    .courses-table th,
    .courses-table td {
        padding: 0.5rem;
    }

    .courses-table input[type="number"] {
        width: 60px;
        padding: 0.3rem 0.25rem;
    }

    .btn-primary {
        width: 100%;
    }

    .progression-controls {
        flex-wrap: wrap;
    }

    .grading-table th,
    .grading-table td {
        padding: 0.75rem 0.5rem;
        font-size: var(--font-size-xs);
    }

    .grade-badge {
        min-width: 35px;
        padding: 0.3rem 0.5rem;
        font-size: 0.75rem;
    }

    .contribute-buttons {
        flex-direction: column;
        gap: 0.75rem;
    }

    .btn-outline {
        width: 100%;
    }

    .footer {
        padding: 2.5rem 1.5rem 1.5rem;
    }

    .footer-divider {
        margin: 2.5rem 0;
    }

    .footer-credit {
        font-size: 0.9rem;
        margin-bottom: 1rem;
    }

    .footer-icons {
        gap: 1.25rem;
        margin-bottom: 1.5rem;
    }

    .footer-icon {
        width: 36px;
        height: 36px;
    }

    .footer-notice {
        font-size: 0.75rem;
        padding: 0 0.5rem;
    }

    .grading-table th,
    .grading-table td {
        padding: 0.6rem 0.4rem;
        font-size: 0.7rem;
    }

    .grade-badge {
        min-width: 32px;
        padding: 0.25rem 0.4rem;
        font-size: 0.7rem;
    }
}

@media (max-width: 480px) {
    :root {
        --spacing-lg: 1rem;
        --spacing-md: 1rem;
        --font-size-2xl: 1.5rem;
        --font-size-xl: 1.25rem;
    }

    .header {
        padding: var(--spacing-md);
    }

    .header-left h1 {
        font-size: var(--font-size-xl);
    }

    .section {
        padding: var(--spacing-md);
    }

    .metric-value {
        font-size: var(--font-size-lg);
    }

    .metric-card {
        min-height: 100px;
    }

    .courses-table {
        font-size: 0.7rem;
    }

    .courses-table th,
    .courses-table td {
        padding: 0.3rem;
    }

    .courses-table input[type="number"] {
        width: 50px;
        padding: 0.2rem;
    }

    .contribute-card {
        padding: 1.5rem 1rem;
    }

    .contribute-title {
        font-size: 1rem;
    }

    .contribute-buttons {
        flex-direction: column;
    }

    .btn-outline {
        padding: 0.65rem 1.25rem;
        font-size: 0.85rem;
    }

    .footer {
        padding: 2rem 1rem 1rem;
    }

    .footer-divider {
        margin: 2rem 0;
    }

    .footer-credit {
        font-size: 0.85rem;
        margin-bottom: 0.75rem;
    }

    .footer-icons {
        gap: 1rem;
        margin-bottom: 1.25rem;
    }

    .footer-icon {
        width: 32px;
        height: 32px;
    }

    .footer-notice {
        font-size: 0.7rem;
    }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

.hidden {
    display: none !important;
}

.visible {
    display: block !important;
}

.error {
    color: var(--color-danger);
    border-color: var(--color-danger) !important;
}

.success {
    color: var(--color-success);
}

.warning {
    color: var(--color-warning);
}

.text-center {
    text-align: center;
}

.mt-sm {
    margin-top: var(--spacing-sm);
}

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

.mt-lg {
    margin-top: var(--spacing-lg);
}

.mb-sm {
    margin-bottom: var(--spacing-sm);
}

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

.mb-lg {
    margin-bottom: var(--spacing-lg);
}