/* ==================== ROOT & VARIABLES ==================== */
:root {
    /* Light Mode Colors */
    --primary-color: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --info-color: #3b82f6;

    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #f0f4f8;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --border-color: #e2e8f0;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 32px rgba(0, 0, 0, 0.12);

    /* Glassmorphism */
    --glass-blur: 10px;
    --glass-opacity: 0.7;

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;

    /* Transitions */
    --transition-fast: 150ms ease-out;
    --transition-base: 250ms ease-out;
    --transition-slow: 350ms ease-out;

    /* Font sizes */
    --font-xs: 0.75rem;
    --font-sm: 0.875rem;
    --font-base: 1rem;
    --font-lg: 1.125rem;
    --font-xl: 1.25rem;
    --font-2xl: 1.5rem;
    --font-3xl: 2rem;
}

/* Dark Mode Variables */
html[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-light: #94a3b8;
    --border-color: #334155;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 32px rgba(0, 0, 0, 0.5);
}

/* ==================== GLOBAL STYLES ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

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

body.no-scroll {
    overflow: hidden;
}

input, textarea, select, button {
    font-family: 'Poppins', sans-serif;
}

/* ==================== NAVBAR ==================== */
.navbar {
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(var(--glass-blur));
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-base);
}

html[data-theme="dark"] .navbar {
    background: rgba(15, 23, 42, 0.8);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-2xl);
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    cursor: pointer;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.nav-link {
    background: transparent;
    border: none;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-secondary);
    cursor: pointer;
    font-size: var(--font-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    white-space: nowrap;
}

.nav-link:hover {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
}

.nav-link.active {
    background: rgba(99, 102, 241, 0.15);
    color: var(--primary-color);
    font-weight: 600;
}

.nav-label {
    display: none;
}

.nav-controls {
    display: flex;
    gap: var(--spacing-md);
}

.btn-icon {
    background: transparent;
    border: none;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    font-size: var(--font-lg);
}

.btn-icon:hover {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
}

/* ==================== MAIN CONTENT ==================== */
.main-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-lg);
    min-height: calc(100vh - 80px);
}

.page {
    display: none;
    animation: fadeIn var(--transition-base);
}

.page.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.page-header {
    margin-bottom: var(--spacing-2xl);
    text-align: center;
}

.page-header h1 {
    font-size: var(--font-3xl);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.page-header p {
    font-size: var(--font-lg);
    color: var(--text-secondary);
}

/* ==================== CALCULATOR CONTAINER ==================== */
.calculator-container {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.18);
    backdrop-filter: blur(10px);
}

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

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
    font-size: var(--font-sm);
}

.form-group input,
.form-group select,
.form-group textarea {
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: var(--font-base);
    color: var(--text-primary);
    background: var(--bg-tertiary);
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

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

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-lg);
}

.form-group.checkbox {
    flex-direction: row;
    align-items: center;
    margin-top: var(--spacing-md);
}

.form-group.checkbox input {
    width: 20px;
    height: 20px;
    margin: 0;
    cursor: pointer;
}

.form-group.checkbox label {
    margin: 0 0 0 var(--spacing-md);
    cursor: pointer;
}

.required {
    color: var(--danger-color);
}

/* ==================== BUTTONS ==================== */
.btn {
    padding: var(--spacing-md) var(--spacing-xl);
    border: none;
    border-radius: var(--radius-lg);
    font-size: var(--font-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
}

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

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

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
}

.btn-secondary {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: rgba(99, 102, 241, 0.2);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-color), #059669);
    color: white;
}

.btn-success:hover {
    background: linear-gradient(135deg, #059669, var(--success-color));
}

.btn-danger {
    background: linear-gradient(135deg, var(--danger-color), #dc2626);
    color: white;
}

.btn-danger:hover {
    background: linear-gradient(135deg, #dc2626, var(--danger-color));
}

.btn-warning {
    background: linear-gradient(135deg, var(--warning-color), #d97706);
    color: white;
}

.btn-warning:hover {
    background: linear-gradient(135deg, #d97706, var(--warning-color));
}

.btn-info {
    background: linear-gradient(135deg, var(--info-color), #2563eb);
    color: white;
}

.btn-info:hover {
    background: linear-gradient(135deg, #2563eb, var(--info-color));
}

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

.button-group {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
    margin: var(--spacing-xl) 0;
}

.button-group.mb-20 {
    margin-bottom: var(--spacing-2xl);
}

/* ==================== RESULTS SECTION ==================== */
.results-section {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl);
    background: rgba(99, 102, 241, 0.05);
    border-left: 4px solid var(--primary-color);
    border-radius: var(--radius-lg);
}

.results-header {
    font-size: var(--font-2xl);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.result-label {
    font-weight: 500;
    color: var(--text-secondary);
}

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

.result-status {
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: var(--font-sm);
    font-weight: 600;
}

.status-good {
    background: rgba(16, 185, 129, 0.2);
    color: var(--success-color);
}

.status-medium {
    background: rgba(245, 158, 11, 0.2);
    color: var(--warning-color);
}

.status-weak {
    background: rgba(239, 68, 68, 0.2);
    color: var(--danger-color);
}

/* ==================== PROGRESS BAR ==================== */
.progress-bar {
    width: 100%;
    height: 8px;
    background: rgba(0, 0, 0, 0.1);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-top: var(--spacing-sm);
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: var(--radius-lg);
    transition: width var(--transition-base);
}

/* ==================== CARD STYLES ==================== */
.card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(255, 255, 255, 0.18);
    transition: all var(--transition-base);
}

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

.card-title {
    font-size: var(--font-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.card-value {
    font-size: var(--font-2xl);
    font-weight: 700;
    color: var(--primary-color);
}

.card-status {
    font-size: var(--font-sm);
    color: var(--text-secondary);
    margin-top: var(--spacing-sm);
}

/* ==================== DASHBOARD ==================== */
.dashboard-container {
    display: grid;
    gap: var(--spacing-2xl);
}

.dashboard-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
}

.stat-card {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(139, 92, 246, 0.1));
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.18);
    text-align: center;
}

.stat-icon {
    font-size: var(--font-3xl);
    margin-bottom: var(--spacing-md);
    color: var(--primary-color);
}

.stat-label {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-sm);
}

.stat-value {
    font-size: var(--font-3xl);
    font-weight: 700;
    color: var(--text-primary);
}

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

/* ==================== SUBJECT CARD ==================== */
.subject-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid rgba(255, 255, 255, 0.18);
    margin-bottom: var(--spacing-md);
}

.subject-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.subject-name {
    font-size: var(--font-lg);
    font-weight: 600;
    color: var(--text-primary);
}

.subject-coef {
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: var(--font-sm);
    font-weight: 600;
}

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

.input-label {
    font-size: var(--font-xs);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-weight: 500;
}

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

.input-group input {
    flex: 1;
}

.btn-remove {
    background: rgba(239, 68, 68, 0.1);
    color: var(--danger-color);
    border: 2px solid var(--danger-color);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: var(--font-sm);
}

.btn-remove:hover {
    background: rgba(239, 68, 68, 0.2);
}

/* ==================== CUSTOM SUBJECTS ==================== */
.custom-subjects-container {
    display: grid;
    gap: var(--spacing-lg);
}

/* ==================== MODAL ==================== */
.modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    animation: fadeIn var(--transition-fast);
    backdrop-filter: blur(4px);
}

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    border: 1px solid rgba(255, 255, 255, 0.18);
    box-shadow: var(--shadow-lg);
    max-width: 500px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideUp var(--transition-base);
}

.modal-content.large {
    max-width: 700px;
}

@keyframes slideUp {
    from {
        transform: translateY(50px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xl);
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    color: var(--text-primary);
    margin: 0;
}

.modal-close {
    background: transparent;
    border: none;
    font-size: var(--font-2xl);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.modal-body {
    padding: var(--spacing-xl);
}

.modal-footer {
    padding: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
    display: flex;
    gap: var(--spacing-md);
    justify-content: flex-end;
    flex-wrap: wrap;
}

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

.help-section h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.help-section p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* ==================== TOAST NOTIFICATION ==================== */
.toast {
    position: fixed;
    bottom: -100px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: var(--bg-primary);
    padding: var(--spacing-lg) var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    z-index: 3000;
    transition: bottom var(--transition-base);
    max-width: 90%;
    text-align: center;
}

.toast.active {
    bottom: var(--spacing-xl);
}

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

.toast.error {
    background: var(--danger-color);
}

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

.toast.info {
    background: var(--info-color);
}

/* ==================== RESPONSIVE DESIGN ==================== */
@media (max-width: 768px) {
    .main-content {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .calculator-container {
        padding: var(--spacing-lg);
    }

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

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

    .page-header h1 {
        font-size: var(--font-2xl);
    }

    .nav-container {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .nav-menu {
        width: 100%;
        justify-content: center;
    }

    .nav-link {
        flex: 1;
        justify-content: center;
    }

    .nav-label {
        display: inline;
    }

    .button-group {
        width: 100%;
        justify-content: stretch;
    }

    .btn {
        flex: 1;
        justify-content: center;
    }

    .dashboard-stats {
        grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    }

    .stat-value {
        font-size: var(--font-2xl);
    }

    .result-item {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }

    .modal-content {
        width: 95%;
        max-height: 95vh;
    }
}

@media (max-width: 480px) {
    :root {
        --spacing-lg: 1rem;
        --font-2xl: 1.25rem;
        --font-3xl: 1.5rem;
    }

    .page-header h1 {
        font-size: var(--font-2xl);
    }

    .page-header p {
        font-size: var(--font-base);
    }

    .btn {
        padding: var(--spacing-md) var(--spacing-lg);
        font-size: var(--font-sm);
    }

    .nav-brand span {
        display: none;
    }

    .dashboard-stats {
        grid-template-columns: 1fr;
    }

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

/* ==================== FOOTER STYLES ==================== */
.app-footer {
    margin-top: auto;
    padding: var(--spacing-2xl) var(--spacing-lg);
    background: linear-gradient(180deg, 
        rgba(99, 102, 241, 0.08), 
        rgba(139, 92, 246, 0.05)
    );
    border-top: 1px solid rgba(255, 255, 255, 0.18);
    backdrop-filter: blur(10px);
    position: relative;
    overflow: hidden;
}

.app-footer::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.1), transparent);
    border-radius: 50%;
    animation: float 15s ease-in-out infinite;
}

.app-footer::after {
    content: '';
    position: absolute;
    bottom: -30%;
    left: -5%;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(139, 92, 246, 0.1), transparent);
    border-radius: 50%;
    animation: float 20s ease-in-out infinite reverse;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) translateX(0px);
    }
    50% {
        transform: translateY(30px) translateX(10px);
    }
}

.footer-content {
    position: relative;
    z-index: 1;
    max-width: 1400px;
    margin: 0 auto;
}

.footer-main {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2xl);
    flex-wrap: wrap;
    text-align: center;
}

.footer-section {
    flex: 1;
    min-width: 250px;
}

.footer-text {
    font-size: var(--font-base);
    color: var(--text-secondary);
    margin: 0 0 var(--spacing-md) 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
}

.footer-text i {
    color: var(--danger-color);
    font-size: 1.2em;
    animation: heartbeat 1.5s ease-in-out infinite;
}

@keyframes heartbeat {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.2);
    }
}

.footer-name {
    font-weight: 700;
    color: var(--primary-color);
    background: rgba(99, 102, 241, 0.1);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-style: italic;
}

.footer-dua {
    font-size: var(--font-sm);
    color: var(--text-light);
    margin: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    font-style: italic;
    letter-spacing: 0.5px;
}

.footer-dua i {
    color: var(--secondary-color);
    font-size: 1.1em;
}

.footer-divider {
    width: 2px;
    height: 40px;
    background: linear-gradient(180deg, 
        rgba(99, 102, 241, 0), 
        rgba(99, 102, 241, 0.5),
        rgba(99, 102, 241, 0)
    );
    display: none;
}

.footer-credits {
    font-size: var(--font-sm);
    color: var(--text-light);
    margin: 0;
    line-height: 1.8;
}

.footer-tagline {
    font-size: var(--font-xs);
    color: var(--primary-color);
    font-weight: 600;
    letter-spacing: 0.5px;
    opacity: 0.8;
}

html[data-theme="dark"] .app-footer {
    background: linear-gradient(180deg, 
        rgba(99, 102, 241, 0.05), 
        rgba(139, 92, 246, 0.02)
    );
}

/* ==================== PRINT STYLES ==================== */
@media print {
    .navbar,
    .nav-controls,
    .button-group,
    .btn {
        display: none !important;
    }

    .app-footer {
        border-top: 1px solid #ccc;
    }

    body {
        background: white;
    }

    .calculator-container,
    .results-section {
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

@media (max-width: 768px) {
    .app-footer {
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .footer-main {
        gap: var(--spacing-lg);
    }

    .footer-divider {
        display: none !important;
    }

    .footer-text,
    .footer-dua,
    .footer-credits {
        font-size: var(--font-sm);
    }

    .footer-name {
        padding: var(--spacing-xs) var(--spacing-xs);
    }
}