/* Design System & Premium CSS for Redox Solver */

:root {
    --bg-color: #0b0b14;
    --card-bg: rgba(20, 20, 35, 0.6);
    --card-border: rgba(255, 255, 255, 0.07);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    
    --primary: #6366f1; /* Indigo */
    --primary-glow: rgba(99, 102, 241, 0.4);
    --secondary: #06b6d4; /* Cyan */
    
    --oxidized-color: #10b981; /* Emerald */
    --oxidized-bg: rgba(16, 185, 129, 0.12);
    --reduced-color: #f43f5e; /* Rose */
    --reduced-bg: rgba(244, 63, 94, 0.12);
    
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-stack: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: var(--font-stack);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    overflow-x: hidden;
    position: relative;
}

/* Background Glowing Elements */
.background-glows {
    position: absolute;
    width: 100vw;
    height: 100vh;
    top: 0;
    left: 0;
    z-index: -1;
    overflow: hidden;
    pointer-events: none;
}

.glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(120px);
    opacity: 0.25;
}

.glow-1 {
    width: 45vw;
    height: 45vw;
    background: radial-gradient(circle, var(--primary) 0%, transparent 70%);
    top: -15%;
    left: -10%;
}

.glow-2 {
    width: 50vw;
    height: 50vw;
    background: radial-gradient(circle, var(--secondary) 0%, transparent 70%);
    bottom: -10%;
    right: -10%;
}

/* App Container Layout */
.app-container {
    width: 100%;
    max-width: 960px;
    padding: 40px 20px;
    display: flex;
    flex-direction: column;
    gap: 30px;
    min-height: 100vh;
}

/* Header Styling */
.app-header {
    text-align: center;
    margin-bottom: 10px;
}

.logo-badge {
    display: inline-flex;
    padding: 6px 14px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--card-border);
    border-radius: 30px;
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.15em;
    color: var(--secondary);
    margin-bottom: 16px;
    text-transform: uppercase;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.app-header h1 {
    font-size: 2.8rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, #ffffff 30%, #94a3b8 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 12px;
}

.app-header .subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 680px;
    margin: 0 auto;
    line-height: 1.6;
    font-weight: 300;
}

/* Main Interactive Card */
.main-card {
    background: var(--card-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border: 1px solid var(--card-border);
    border-radius: 24px;
    padding: 36px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3), 
                inset 0 1px 0 rgba(255, 255, 255, 0.05);
    display: flex;
    flex-direction: column;
    gap: 30px;
    min-width: 0;
    width: 100%;
}

/* Presets Panel */
.presets-section {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.section-label {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--text-muted);
    font-weight: 600;
}

.presets-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.preset-btn {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    padding: 10px 16px;
    color: var(--text-secondary);
    font-family: var(--font-stack);
    font-size: 0.88rem;
    font-weight: 400;
    cursor: pointer;
    transition: var(--transition-smooth);
}

.preset-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.2);
    color: var(--text-primary);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

/* Form Styles */
.solver-form {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.field-label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 8px;
    display: block;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

#equation-input {
    width: 100%;
    background: rgba(0, 0, 0, 0.25);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 18px 50px 18px 20px;
    color: var(--text-primary);
    font-family: var(--font-stack);
    font-size: 1.15rem;
    font-weight: 400;
    transition: var(--transition-smooth);
    box-shadow: inset 0 2px 8px rgba(0,0,0,0.2);
}

#equation-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px var(--primary-glow),
                inset 0 2px 8px rgba(0,0,0,0.2);
}

.clear-btn {
    position: absolute;
    right: 18px;
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 1.6rem;
    cursor: pointer;
    line-height: 1;
    display: none;
    transition: var(--transition-smooth);
}

.clear-btn:hover {
    color: var(--text-primary);
}

/* Segmented Control Options */
.options-row {
    display: flex;
    justify-content: space-between;
    align-items: flex-end;
    gap: 24px;
    flex-wrap: wrap;
}

.medium-selector-group {
    flex-grow: 1;
}

.segmented-control {
    display: flex;
    background: rgba(0, 0, 0, 0.25);
    border: 1px solid var(--card-border);
    padding: 4px;
    border-radius: 14px;
    width: 100%;
    max-width: 480px;
}

.segmented-control input[type="radio"] {
    display: none;
}

.segmented-control label {
    flex: 1;
    text-align: center;
    padding: 12px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: 10px;
    cursor: pointer;
    transition: var(--transition-smooth);
    user-select: none;
}

.segmented-control input[type="radio"]:checked + label {
    background: rgba(255, 255, 255, 0.08);
    color: var(--text-primary);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.segmented-control label:hover {
    color: var(--text-primary);
}

/* Submit Button */
.submit-btn {
    background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%);
    border: none;
    border-radius: 16px;
    padding: 16px 28px;
    color: #ffffff;
    font-family: var(--font-stack);
    font-size: 1rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    transition: var(--transition-smooth);
    box-shadow: 0 8px 24px rgba(99, 102, 241, 0.25);
}

.submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 28px rgba(99, 102, 241, 0.4);
}

.btn-icon {
    width: 18px;
    height: 18px;
    transition: var(--transition-smooth);
}

.submit-btn:hover .btn-icon {
    transform: translateX(4px);
}

/* Error Banner */
.error-banner {
    display: flex;
    align-items: center;
    gap: 12px;
    background: rgba(244, 63, 94, 0.08);
    border: 1px solid rgba(244, 63, 94, 0.25);
    border-radius: 16px;
    padding: 16px 20px;
    color: var(--reduced-color);
    font-size: 0.95rem;
    line-height: 1.5;
    animation: fadeIn 0.4s ease-out;
}

.error-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

/* Results Section & Cards */
.results-container {
    display: flex;
    flex-direction: column;
    gap: 24px;
    animation: slideUp 0.5s cubic-bezier(0.4, 0, 0.2, 1);
    min-width: 0;
    width: 100%;
}

.result-card {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--card-border);
    border-radius: 18px;
    padding: 24px;
    box-shadow: 0 4px 20px rgba(0,0,0,0.1);
    min-width: 0;
    width: 100%;
}

.result-card h2 {
    font-size: 1.15rem;
    font-weight: 600;
    letter-spacing: -0.01em;
    color: var(--text-primary);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Balanced Equation Specifics */
.equation-card {
    background: radial-gradient(circle at top left, rgba(99, 102, 241, 0.06) 0%, transparent 50%),
                rgba(255, 255, 255, 0.02);
    text-align: center;
}

.result-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.result-card-header h2 {
    margin-bottom: 0;
}

.card-tag {
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.08em;
    padding: 4px 10px;
    background: rgba(99, 102, 241, 0.15);
    color: #a5b4fc;
    border-radius: 6px;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.balanced-output {
    font-size: 1.8rem;
    font-weight: 400;
    letter-spacing: -0.01em;
    padding: 16px;
    color: #e2e8f0;
    line-height: 1.4;
    overflow-x: auto;
    white-space: nowrap;
    width: 100%;
    -webkit-overflow-scrolling: touch;
}

.balanced-output sub {
    font-size: 0.95rem;
    bottom: -0.2em;
    color: var(--text-secondary);
}

.balanced-output sup {
    font-size: 0.95rem;
    top: -0.45em;
    color: var(--secondary);
}

.balanced-output .coef {
    font-weight: 700;
    color: #ffffff;
    font-size: 1.9rem;
}

/* Results Grid Layout */
.results-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}

@media (max-width: 768px) {
    .results-grid {
        grid-template-columns: 1fr;
    }
}

/* Redox Analysis card items */
.analysis-block {
    margin-bottom: 20px;
    border-bottom: 1px solid var(--card-border);
    padding-bottom: 20px;
}

.block-title {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
}

.block-title h3 {
    font-size: 0.92rem;
    font-weight: 500;
    color: var(--text-secondary);
}

.badge {
    font-size: 0.75rem;
    font-weight: 600;
    padding: 3px 8px;
    border-radius: 6px;
}

.badge-oxidized {
    color: var(--oxidized-color);
    background: var(--oxidized-bg);
}

.badge-reduced {
    color: var(--reduced-color);
    background: var(--reduced-bg);
}

.details-list {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.detail-item {
    font-size: 0.92rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.detail-item .highlight {
    font-weight: 600;
    color: var(--text-primary);
}

.detail-item .ox-num {
    font-weight: 700;
    color: var(--secondary);
}

.detail-item sub {
    font-size: 0.65rem;
}
.detail-item sup {
    font-size: 0.65rem;
}

.detail-item.muted {
    color: var(--text-muted);
    font-style: italic;
}

/* Agents Blocks */
.agents-block {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding-top: 4px;
}

.agent-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.agent-label {
    font-size: 0.92rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.agent-value {
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 8px;
    font-size: 0.88rem;
}

/* Oxidation States Table */
.table-container {
    overflow-x: auto;
    width: 100%;
    -webkit-overflow-scrolling: touch;
}

.states-table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
    font-size: 0.92rem;
}

.states-table th, .states-table td {
    padding: 14px 16px;
    border-bottom: 1px solid var(--card-border);
}

.states-table th {
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.78rem;
    letter-spacing: 0.08em;
}

.formula-cell {
    font-weight: 500;
    font-size: 1.05rem;
    color: var(--text-primary);
}

.formula-cell sub { font-size: 0.7rem; }
.formula-cell sup { font-size: 0.7rem; color: var(--secondary); }

.state-chip {
    display: inline-flex;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--card-border);
    border-radius: 8px;
    padding: 4px 8px;
    margin-right: 6px;
    margin-bottom: 6px;
    font-size: 0.82rem;
}

.state-chip .ox-num {
    font-weight: 700;
    color: var(--secondary);
    margin-left: 4px;
}

/* Footer Styling */
.app-footer {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.8rem;
    margin-top: 10px;
    margin-bottom: 20px;
}

/* Utility Animations */
.hidden {
    display: none !important;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Half Reaction Display in Redox Analysis */
.half-reaction-wrapper {
    margin-top: 16px;
    background: rgba(0, 0, 0, 0.15);
    border-radius: 12px;
    padding: 14px 16px;
    border: 1px dashed rgba(255, 255, 255, 0.08);
    min-width: 0;
    width: 100%;
}

.half-reaction-label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 8px;
}

.half-reaction-eq {
    font-size: 1.25rem;
    color: var(--text-primary);
    overflow-x: auto;
    white-space: nowrap;
    line-height: 1.4;
    padding-bottom: 6px;
    width: 100%;
    -webkit-overflow-scrolling: touch;
}

.half-reaction-eq .coef {
    font-weight: 700;
}

.half-reaction-eq sub {
    font-size: 0.75rem;
    bottom: -0.1em;
}

.half-reaction-eq sup {
    font-size: 0.75rem;
    top: -0.3em;
}

/* Guidelines Accordion Styling */
.guidelines-details {
    background: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--card-border);
    border-radius: 16px;
    padding: 6px 16px;
    transition: var(--transition-smooth);
    margin-bottom: 8px;
}

.guidelines-details[open] {
    background: rgba(255, 255, 255, 0.04);
    border-color: rgba(255, 255, 255, 0.12);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    padding: 16px;
}

.guidelines-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 10px 0;
    list-style: none; /* Hide default arrow */
    user-select: none;
    transition: var(--transition-smooth);
}

.guidelines-summary::-webkit-details-marker {
    display: none; /* Hide default arrow in Safari */
}

.guidelines-summary:hover {
    color: var(--text-primary);
}

.guidelines-summary::after {
    content: "+";
    font-size: 1.25rem;
    font-weight: 400;
    transition: var(--transition-smooth);
}

.guidelines-details[open] .guidelines-summary::after {
    content: "−";
    transform: rotate(180deg);
}

.guidelines-content {
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--card-border);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 640px) {
    .guidelines-content {
        grid-template-columns: 1fr;
    }
}

.guideline-col {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.guideline-col h4 {
    font-size: 0.9rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: flex;
    align-items: center;
    gap: 8px;
}

.guideline-col.dos h4 {
    color: var(--oxidized-color);
}

.guideline-col.donts h4 {
    color: var(--reduced-color);
}

.guideline-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.guideline-list li {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.5;
    position: relative;
    padding-left: 20px;
}

.guideline-list li::before {
    position: absolute;
    left: 0;
    top: 2px;
    font-weight: 700;
}

.guideline-col.dos li::before {
    content: "✓";
    color: var(--oxidized-color);
}

.guideline-col.donts li::before {
    content: "✗";
    color: var(--reduced-color);
}

.guideline-list code {
    background: rgba(0, 0, 0, 0.25);
    padding: 2px 6px;
    border-radius: 4px;
    font-family: monospace;
    font-size: 0.85rem;
    color: var(--text-primary);
}

/* Premium Switch Toggle */
.settings-group {
    display: flex;
    flex-direction: column;
}

.toggle-control {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    user-select: none;
    padding: 10px 0;
}

.toggle-control input {
    display: none;
}

.toggle-slider {
    position: relative;
    width: 44px;
    height: 22px;
    background-color: rgba(255, 255, 255, 0.08);
    border: 1px solid var(--card-border);
    border-radius: 20px;
    transition: var(--transition-smooth);
}

.toggle-slider::before {
    content: "";
    position: absolute;
    height: 14px;
    width: 14px;
    left: 3px;
    bottom: 3px;
    background-color: var(--text-secondary);
    border-radius: 50%;
    transition: var(--transition-smooth);
}

.toggle-control input:checked + .toggle-slider {
    background-color: rgba(99, 102, 241, 0.2);
    border-color: var(--primary);
}

.toggle-control input:checked + .toggle-slider::before {
    transform: translateX(22px);
    background-color: var(--primary);
}

.toggle-label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: var(--transition-smooth);
}

.toggle-control:hover .toggle-label {
    color: var(--text-primary);
}

/* Back Button Styling */
.back-btn {
    align-self: flex-start;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    padding: 10px 16px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--card-border);
    border-radius: 12px;
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    transition: var(--transition-smooth);
    cursor: pointer;
    margin-bottom: -10px;
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.08);
    border-color: rgba(255, 255, 255, 0.2);
    color: var(--text-primary);
    transform: translateX(-4px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.back-icon {
    width: 16px;
    height: 16px;
    transition: var(--transition-smooth);
}

.back-btn:hover .back-icon {
    transform: translateX(-2px);
}

/* Styled scrollbars for horizontal scrolling elements */
.balanced-output::-webkit-scrollbar,
.half-reaction-eq::-webkit-scrollbar,
.table-container::-webkit-scrollbar {
    height: 6px;
}

.balanced-output::-webkit-scrollbar-track,
.half-reaction-eq::-webkit-scrollbar-track,
.table-container::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.15);
    border-radius: 3px;
}

.balanced-output::-webkit-scrollbar-thumb,
.half-reaction-eq::-webkit-scrollbar-thumb,
.table-container::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.12);
    border-radius: 3px;
}

.balanced-output::-webkit-scrollbar-thumb:hover,
.half-reaction-eq::-webkit-scrollbar-thumb:hover,
.table-container::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.25);
}

/* Mobile responsive adjustments */
@media (max-width: 640px) {
    .app-container {
        padding: 24px 12px;
        gap: 20px;
    }

    .app-header h1 {
        font-size: 2.1rem;
    }

    .app-header .subtitle {
        font-size: 0.95rem;
    }

    .main-card {
        padding: 20px 16px;
        border-radius: 16px;
        gap: 24px;
    }

    .presets-grid {
        gap: 8px;
    }

    .preset-btn {
        padding: 8px 12px;
        font-size: 0.8rem;
    }

    #equation-input {
        padding: 14px 44px 14px 16px;
        font-size: 1rem;
    }

    .segmented-control label {
        padding: 10px 8px;
        font-size: 0.82rem;
    }

    .submit-btn {
        padding: 14px 20px;
        font-size: 0.95rem;
        width: 100%;
        justify-content: center;
    }

    .result-card {
        padding: 16px;
        border-radius: 14px;
    }

    .balanced-output {
        font-size: 1.35rem;
        padding: 12px 8px;
    }

    .half-reaction-eq {
        font-size: 1.05rem;
        padding-bottom: 6px;
    }

    .table-container th, .table-container td {
        padding: 10px 8px;
    }
}