:root {
    --primary-color: #4f46e5;
    --primary-light: #e0e7ff;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    --background-color: #f3f4f6;
    --card-background: #ffffff;
    --text-color: #1f2937;
    --subtle-text-color: #6b7280;
    --border-color: #e5e7eb;
    --danger-color: #ef4444;
    --danger-light: #fee2e2;
    --success-color: #10b981;
    --success-light: #d1fae5;
    --font-family: 'Inter', sans-serif;
}

body {
    font-family: var(--font-family);
    background-color: var(--background-color);
    color: var(--text-color);
    margin: 0;
    padding: 1rem;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

/* Navigation */
nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.5rem 1rem;
    background-color: var(--card-background);
    border-radius: 0.75rem;
    box-shadow: 0 2px 4px -1px rgb(0 0 0 / 0.06);
    margin-bottom: 2rem;
}

.nav-left {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.logo {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-color);
}

.tabs {
    display: flex;
    gap: 0.5rem;
}

.tab-link {
    background: none;
    border: none;
    padding: 0.5rem 1rem;
    font-size: 1rem;
    font-weight: 600;
    color: var(--subtle-text-color);
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.2s ease-in-out;
}

.tab-link:hover {
    background-color: var(--primary-light);
    color: var(--primary-color);
}

.tab-link.active {
    background-color: var(--primary-color);
    color: white;
}

.github-link {
    color: var(--text-color);
    display: flex;
    align-items: center;
}

.github-logo {
    width: 28px;
    height: 28px;
    transition: color 0.2s;
}

.github-link:hover .github-logo {
    color: var(--primary-color);
}


header {
    text-align: center;
    margin-bottom: 2rem;
}

h1 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--text-color);
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    border-bottom: 2px solid var(--primary-light);
    padding-bottom: 0.5rem;
    margin-top: 0;
    margin-bottom: 1.5rem;
}

h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-top: 1.5rem;
    margin-bottom: 1rem;
}

.card {
    background-color: var(--card-background);
    border-radius: 0.75rem;
    padding: 1.5rem;
    box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

.grid-container {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

@media (min-width: 992px) {
    .grid-container {
        grid-template-columns: 1fr 1fr;
    }
}

.grid-item {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Tab Content */
.tab-content.hidden {
    display: none;
}

/* Info & Usage Page */
.info-card {
    padding: 2rem;
}
.info-card h3 {
    color: var(--primary-color);
    margin-top: 2rem;
}
.info-card ul {
    padding-left: 20px;
}
.info-card li {
    margin-bottom: 0.75rem;
}
.info-card code {
    background-color: var(--primary-light);
    color: var(--primary-color);
    padding: 0.2rem 0.4rem;
    border-radius: 0.25rem;
    font-weight: 600;
}


/* Forms and Buttons */
.form-group {
    margin-bottom: 1rem;
}

.form-group-toggle {
    display: flex;
    align-items: center;
    background-color: var(--primary-light);
    border-radius: 0.5rem;
    padding: 0.75rem 1rem;
    margin-bottom: 1.5rem;
}

.form-group-toggle input[type="checkbox"] {
    width: 1.25em;
    height: 1.25em;
    margin-right: 0.75rem;
    accent-color: var(--primary-color);
}

.form-group-toggle label {
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 0;
    cursor: pointer;
}

#semester-options {
    background-color: #f8f9fa;
    border: 1px dashed var(--border-color);
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
}

label {
    display: block;
    font-weight: 500;
    margin-bottom: 0.5rem;
}

input[type="number"],
input[type="text"],
select {
    width: 100%;
    padding: 0.75rem;
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    background-color: #f9fafb;
    box-sizing: border-box;
    font-size: 1rem;
}

input:focus, select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px var(--primary-light);
}

button {
    background-color: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
    width: 100%;
    margin-top: 0.5rem;
}

button:hover {
    background-color: #4338ca;
}

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

button.danger:hover {
    background-color: #dc2626;
}

button:disabled,
button:disabled:hover {
    background-color: #9ca3af;
    cursor: not-allowed;
}


.info, .info.small {
    padding: 0.5rem 0 0 0;
    font-size: 0.8rem;
    color: var(--subtle-text-color);
    background: none;
    border: none;
    margin-bottom: 0;
}

.manual-entry, .csv-entry {
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
    margin-top: 1.5rem;
}

.csv-sample-container {
    margin: 1rem 0;
    padding: 1rem;
    background-color: #f8f9fa;
    border: 1px dashed var(--border-color);
    border-radius: 0.5rem;
    text-align: center;
}

.csv-sample-image {
    max-width: 100%;
    height: auto;
    border-radius: 0.25rem;
}

.file-upload-input {
    display: none;
}

.file-upload-label {
    display: inline-block;
    background-color: var(--secondary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    text-align: center;
    transition: background-color 0.2s;
    width: 100%;
    box-sizing: border-box;
}
.file-upload-label:hover {
    background-color: #059669;
}


/* Tables */
.table-container {
    max-height: 280px;
    overflow-y: auto;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
}

table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

th, td {
    padding: 0.75rem 1rem;
    border-bottom: 1px solid var(--border-color);
    white-space: nowrap;
    vertical-align: middle;
}

thead {
    background-color: #f9fafb;
    position: sticky;
    top: 0;
    z-index: 10;
}

th[data-sort] {
    cursor: pointer;
    user-select: none;
}
th[data-sort]:hover {
    background-color: #f0f0f0;
}
.sort-icon {
    font-size: 0.8em;
    margin-left: 0.5em;
    color: var(--subtle-text-color);
    display: inline-block;
    width: 1em;
}

tbody tr:last-child td {
    border-bottom: none;
}

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

.table-actions {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}
.table-actions button {
    width: 50%;
}

td input,
td select {
    padding: 0.5rem;
    font-size: 0.95rem;
    width: 90%;
    border-radius: 0.25rem;
    border: 1px solid var(--border-color);
}
td input:focus,
td select:focus {
    border-color: var(--primary-color);
    outline: none;
}

td .action-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-weight: 600;
    padding: 0.25rem;
    width: auto;
    margin: 0 0.25rem;
    font-size: 0.875rem;
}
td .edit-btn { color: var(--primary-color); }
td .save-btn { color: var(--success-color); }
td .cancel-btn { color: var(--subtle-text-color); }
td .delete-btn { color: var(--danger-color); }

td .action-btn:hover {
    text-decoration: underline;
}


/* GPA Analysis & Progression */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}
.settings-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}


.stat-item {
    background-color: #f9fafb;
    padding: 1rem;
    border-radius: 0.5rem;
    text-align: center;
}

.stat-title {
    display: block;
    font-size: 0.875rem;
    color: var(--subtle-text-color);
    margin-bottom: 0.25rem;
}

.stat-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

#progression-view {
    margin-top: 1rem;
}

.progress-bar-container {
    width: 100%;
    background-color: var(--border-color);
    border-radius: 999px;
    height: 1.25rem;
    overflow: hidden;
    margin-top: 1rem;
}

#progress-bar {
    height: 100%;
    background-color: var(--secondary-color);
    border-radius: 999px;
    transition: width 0.5s ease-in-out;
}

#progression-details {
    margin-top: 0.5rem;
    text-align: center;
    font-weight: 500;
    color: var(--subtle-text-color);
}


/* Prediction Results & Semester Analysis */
.hidden {
    display: none !important;
}

.prediction-hours-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(60px, 1fr));
    gap: 0.5rem;
    margin-top: 0.5rem;
}
.prediction-hours-grid input {
    text-align: center;
    padding: 0.5rem;
}

#prediction-summary {
    font-weight: 500;
    margin-bottom: 1rem;
}

#prediction-filter {
    background-color: #f8f9fa;
    padding: 1rem;
    border-radius: 0.5rem;
    margin-bottom: 1rem;
}
#prediction-filter label {
    font-weight: 600;
    margin-bottom: 0.5rem;
}
#prediction-filter span {
    font-family: monospace;
    background-color: var(--primary-light);
    color: var(--primary-color);
    padding: 0.1rem 0.4rem;
    border-radius: 0.25rem;
}
input[type="range"] {
    width: 100%;
    accent-color: var(--primary-color);
}

.likelihood-bar-container {
    width: 100%;
    height: 1.5rem;
    background-color: var(--border-color);
    border-radius: 0.25rem;
}
.likelihood-bar {
    height: 100%;
    background-color: var(--primary-color);
    border-radius: 0.25rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 0.8rem;
    font-weight: 600;
}
.viz-col {
    min-width: 150px;
}

.chart-wrapper {
    position: relative;
    height: 300px;
    width: 100%;
}

#semester-table-container {
    margin-top: 1.5rem;
    max-height: 300px;
}

/* Loading Overlay & Message Box */
#loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(4px);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.spinner {
    border: 6px solid var(--border-color);
    border-top: 6px solid var(--primary-color);
    border-radius: 50%;
    width: 50px;
    height: 50px;
    animation: spin 1s linear infinite;
}

#loading-overlay p {
    margin-top: 1rem;
    font-weight: 500;
    font-size: 1.125rem;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

#message-box {
    padding: 1rem 1.5rem;
    border-radius: 0.5rem;
    margin-bottom: 1.5rem;
    font-weight: 500;
    color: white;
    opacity: 1;
    transition: opacity 0.5s;
}
#message-box.hidden {
    display: block !important;
    opacity: 0;
    pointer-events: none;
}
#message-box.error { background-color: var(--danger-color); }
#message-box.success { background-color: var(--success-color); }