:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --info-color: #0ea5e9;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --card-bg: #ffffff;
    --card-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --border-color: #e0e0e0;
    --input-bg: transparent;
    --input-border: #cbd5e1;
    --table-bg: #f5f5f5;
    --table-border: #e0e0e0;
}

body.dark-mode {
    --bg-primary: #1a1a2e;
    --bg-secondary: #16213e;
    --bg-tertiary: #0f3460;
    --text-primary: #ffffff;
    --text-secondary: #b0b0b0;
    --card-bg: #16213e;
    --card-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
    --border-color: #2d3e5f;
    --input-bg: transparent;
    --input-border: #3d5a80;
    --table-bg: #0f3460;
    --table-border: #2d3e5f;
}

/* ---------- BASE ---------- */

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

html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: background 0.3s ease, color 0.3s ease;
    min-height: 100vh;
    padding: 1rem;
}

.container {
    max-width: 640px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

/* ---------- HEADER ---------- */

.header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 1.5rem;
    box-shadow: var(--card-shadow);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

.branding {
    flex: 1;
}

.title {
    font-size: clamp(1.6rem, 5vw, 2.1rem);
    font-weight: 800;
    letter-spacing: -0.04em;
    background: linear-gradient(120deg, #4f46e5, #22c55e);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.25rem;
}

.tagline {
    font-size: clamp(0.75rem, 2vw, 0.875rem);
    color: var(--text-secondary);
    font-weight: 500;
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.theme-toggle {
    width: 2.5rem;
    height: 2.5rem;
    border: 1px solid var(--border-color);
    background: var(--bg-secondary);
    border-radius: 999px;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    color: var(--text-primary);
}

.theme-toggle:hover {
    transform: translateY(-1px);
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.theme-toggle:active {
    transform: translateY(0);
}

/* ---------- CARDS ---------- */

.main-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.calculator-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 1.5rem;
    padding: 1.5rem;
    box-shadow: var(--card-shadow);
    animation: slideUp 0.4s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section-title {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.guidelines {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.input-error-message {
    font-size: 0.875rem;
    color: var(--danger-color);
    margin-bottom: 0.75rem;
    min-height: 1.1rem;
}

/* ---------- INPUTS ---------- */

.input-group {
    position: relative;
    margin-bottom: 1.5rem;
    display: flex;
    flex-direction: column;
}

.floating-label {
    font-size: 0.78rem;
    color: var(--text-secondary);
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 0.5rem;
}

.grade-input {
    width: 100%;
    padding: 0.9rem 1.1rem;
    font-size: 0.98rem;
    border: 1.5px solid var(--input-border);
    border-radius: 0.9rem;
    background: var(--input-bg);
    color: var(--text-primary);
    transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
    font-weight: 500;
}

.grade-input::-webkit-outer-spin-button,
.grade-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.grade-input[type=number] {
    -moz-appearance: textfield;
}

.grade-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.18);
    background: rgba(148, 163, 184, 0.04);
}

.input-error {
    border-color: var(--danger-color);
    box-shadow: 0 0 0 2px rgba(239, 68, 68, 0.2);
}

/* ---------- BUTTONS ---------- */

.button-group {
    display: flex;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

.btn {
    flex: 1;
    padding: 0.9rem 1rem;
    font-size: 0.95rem;
    font-weight: 600;
    border: none;
    border-radius: 0.9rem;
    cursor: pointer;
    transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

#saveBtn {
    display: block;
    margin: 0 auto;
    width: auto;
    padding: 0.9rem 2rem;
}

#computeGWABtn {
    flex: 0;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(99, 102, 241, 0.4);
}

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

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    transform: translateY(-1px);
}

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

.btn-danger {
    background: var(--danger-color);
    color: white;
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.btn-danger:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(239, 68, 68, 0.4);
}

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

/* ---------- RESULTS SECTION ---------- */

.results-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.results-subtitle {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.result-display {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-bottom: 2rem;
}

.result-item {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    padding: 1.3rem 1.2rem;
    background: var(--bg-secondary);
    border-radius: 1rem;
    border: 1px solid var(--border-color);
}

.result-item.highlight {
    border-width: 1.5px;
    border-color: var(--primary-color);
    background: var(--bg-secondary);
}

.result-label {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.09em;
}

.result-value {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -0.04em;
    display: inline-flex;
    align-items: baseline;
    gap: 0.2rem;
    color: var(--primary-color);
}

.result-value.small {
    font-size: 1.7rem;
}

.result-value-container {
    display: flex;
    align-items: baseline;
    gap: 0.3rem;
}

.result-unit {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
}

.result-chip {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.6rem 1.2rem;
    border-radius: 999px;
    font-size: 0.85rem;
    font-weight: 700;
    border: 2px solid;
    color: white;
    background: var(--text-secondary);
    border-color: var(--text-secondary);
    text-transform: capitalize;
    letter-spacing: 0.05em;
}

.result-chip.excellent {
    background: var(--success-color);
    border-color: var(--success-color);
}

.result-chip.very-good {
    background: var(--info-color);
    border-color: var(--info-color);
}

.result-chip.satisfactory {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.result-chip.fair {
    background: var(--warning-color);
    border-color: var(--warning-color);
}

.result-chip.failed {
    background: var(--danger-color);
    border-color: var(--danger-color);
}

.result-chip.neutral {
    background: var(--bg-tertiary);
    border-color: var(--border-color);
    color: var(--text-secondary);
}

/* ---------- TABLE ---------- */

.table-subtitle {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
    font-weight: 500;
}

.table-wrapper {
    overflow-x: auto;
}

.grades-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
}

.grades-table thead {
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.grades-table th {
    padding: 0.9rem;
    text-align: left;
    font-weight: 700;
    color: var(--text-primary);
    text-transform: uppercase;
    letter-spacing: 0.09em;
    font-size: 0.78rem;
}

.grades-table td {
    padding: 0.8rem 0.9rem;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-primary);
    font-weight: 500;
}

.grades-table tbody tr {
    transition: background 0.18s ease;
}

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

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

.badge {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    border-radius: 999px;
    font-weight: 600;
    font-size: 0.78rem;
    border: 1px solid;
}

.badge.excellent {
    background: var(--success-color);
    color: white;
    border-color: var(--success-color);
}

.badge.very-good {
    background: var(--info-color);
    color: white;
    border-color: var(--info-color);
}

.badge.satisfactory {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.badge.fair {
    background: var(--warning-color);
    color: white;
    border-color: var(--warning-color);
}

.badge.failed {
    background: var(--danger-color);
    color: white;
    border-color: var(--danger-color);
}

/* ---------- SAVED RECORDS ---------- */

.saved-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    gap: 1rem;
}

.records-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.record-card {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 1rem;
    padding: 1.4rem;
    animation: slideUp 0.3s ease;
    transition: border-color 0.18s ease, box-shadow 0.18s ease, transform 0.18s ease;
}

.record-card:hover {
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.2);
    transform: translateY(-2px);
}

.record-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-bottom: 0.9rem;
    border-bottom: 1px solid var(--border-color);
}

.record-subject {
    font-weight: 800;
    color: var(--text-primary);
    font-size: 1.05rem;
    letter-spacing: 0.03em;
}

.record-delete {
    background: var(--danger-color);
    color: white;
    border: none;
    padding: 0.45rem 0.75rem;
    border-radius: 0.6rem;
    cursor: pointer;
    font-weight: 600;
    transition: transform 0.15s ease, box-shadow 0.15s ease;
    font-size: 0.85rem;
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
}

.record-delete:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(239, 68, 68, 0.3);
}

.record-delete:active {
    transform: translateY(0);
}

.record-grades {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: 1.1rem;
}

.record-grade-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.8rem;
}

.record-grade-item {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
    padding: 0.8rem 1rem;
    background: var(--card-bg);
    border-radius: 0.6rem;
    border: 1px solid var(--border-color);
}

.grade-label {
    font-size: 0.7rem;
    color: var(--text-secondary);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.grade-value {
    font-size: 1.15rem;
    font-weight: 800;
    color: var(--text-primary);
}

.record-results {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.2rem;
    margin-top: 1.5rem;
}

.record-result-item {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding: 1.1rem;
    border-radius: 0.8rem;
    text-align: center;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
}

.record-result-item.excellent {
    background: linear-gradient(135deg, rgba(16, 185, 129, 0.4), rgba(16, 185, 129, 0.5)) !important;
    border-color: var(--success-color) !important;
    border-width: 2px !important;
}

.record-result-item.very-good {
    background: linear-gradient(135deg, rgba(14, 165, 233, 0.4), rgba(14, 165, 233, 0.5)) !important;
    border-color: var(--info-color) !important;
    border-width: 2px !important;
}

.record-result-item.satisfactory {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.4), rgba(99, 102, 241, 0.5)) !important;
    border-color: var(--primary-color) !important;
    border-width: 2px !important;
}

.record-result-item.fair {
    background: linear-gradient(135deg, rgba(245, 158, 11, 0.4), rgba(245, 158, 11, 0.5)) !important;
    border-color: var(--warning-color) !important;
    border-width: 2px !important;
}

.record-result-item.failed {
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.4), rgba(239, 68, 68, 0.5)) !important;
    border-color: var(--danger-color) !important;
    border-width: 2px !important;
}

.record-result-item .result-label {
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    opacity: 0.7;
    color: var(--text-secondary);
}

.record-result-item .result-value {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--text-primary);
}

/* ---------- COMPUTE RESULT SECTION ---------- */

.compute-result-section {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.subject-breakdown {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: 1.5rem;
}

.subject-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.9rem 1.2rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.7rem;
    font-size: 0.9rem;
}

.subject-name {
    font-weight: 700;
    color: var(--text-primary);
}

.subject-grade {
    color: var(--primary-color);
    font-weight: 600;
}

/* ---------- MODALS ---------- */

.modal {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    padding: 1rem;
}

.modal-content {
    background: var(--card-bg);
    border-radius: 1.4rem;
    padding: 2rem;
    max-width: 400px;
    width: 100%;
    animation: slideUp 0.3s ease;
    border: 1px solid var(--border-color);
    box-shadow: var(--card-shadow);
}

.modal-icon {
    width: 3.5rem;
    height: 3.5rem;
    background: rgba(239, 68, 68, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.3rem;
    font-size: 1.8rem;
    color: var(--danger-color);
}

.modal-content h3 {
    font-size: 1.4rem;
    margin-bottom: 0.9rem;
    color: var(--text-primary);
    text-align: center;
}

.modal-message {
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: 1.4rem;
    line-height: 1.6;
}

.modal-input {
    width: 100%;
    padding: 0.9rem 1rem;
    font-size: 0.95rem;
    border: 1.5px solid var(--input-border);
    border-radius: 0.9rem;
    background: var(--input-bg);
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.modal-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(99, 102, 241, 0.18);
}

.modal-error {
    color: var(--danger-color);
    font-size: 0.85rem;
    margin-bottom: 1rem;
    min-height: 1.1rem;
}

.modal-buttons {
    display: flex;
    gap: 0.75rem;
}

/* ---------- RESPONSIVE ---------- */

@media (max-width: 480px) {
    body {
        padding: 0.75rem;
    }

    .container {
        gap: 1.25rem;
    }

    .header {
        padding: 1.1rem;
        border-radius: 1.2rem;
    }

    .calculator-card {
        padding: 1.2rem;
        border-radius: 1.2rem;
    }

    .result-display {
        grid-template-columns: 1fr;
    }

    .result-item.highlight {
        order: -1;
    }

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

    .saved-header {
        flex-direction: column;
        align-items: stretch;
    }

    #computeGWABtn {
        flex: 1;
    }

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

    .record-results {
        grid-template-columns: 1fr;
    }
}

@media (min-width: 768px) {
    .container {
        max-width: 900px;
    }
}