/* ============================================
   NLSE SOLVER - MODERN PREMIUM DESIGN
   ============================================ */

/* --- CSS Variables (Design Tokens) --- */
:root {
    /* Primary Gradient & Accent */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --accent-color: #667eea;
    --accent-hover: #5a6fd6;
    --accent-light: rgba(102, 126, 234, 0.15);

    /* Background & Surface */
    --bg-base: #f0f4f8;
    --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #e4e9f2 100%);
    --surface-glass: rgba(255, 255, 255, 0.85);
    --surface-solid: #ffffff;

    /* Text */
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #718096;

    /* Borders & Shadows */
    --border-light: rgba(102, 126, 234, 0.2);
    --border-subtle: #e2e8f0;
    --shadow-sm: 0 2px 8px rgba(102, 126, 234, 0.08);
    --shadow-md: 0 8px 30px rgba(102, 126, 234, 0.12);
    --shadow-lg: 0 15px 50px rgba(102, 126, 234, 0.18);
    --shadow-glow: 0 0 20px rgba(102, 126, 234, 0.3);

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);

    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;

    /* Status Colors */
    --success: #48bb78;
    --error: #fc8181;
    --warning: #f6ad55;
    --info: #63b3ed;
}

/* --- Base Styles --- */
* {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    margin: 0;
    padding: 0;
    color: var(--text-primary);
    line-height: 1.6;
}

/* --- Container --- */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1.5rem 2rem 4rem;
}

/* --- Header Ribbon --- */
.header-ribbon {
    background: var(--surface-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    padding: 1.25rem 2rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.6);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
   position: relative;
}

.ribbon-left {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.ribbon-left h1 {
    font-size: 1.75rem;
    font-weight: 700;
    margin: 0;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

.ribbon-left .copyright {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.ribbon-left .copyright a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
}

.ribbon-left .copyright a:hover {
    text-decoration: underline;
}

.ribbon-right {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 0.9rem;
}

.ribbon-right .separator {
    color: var(--border-light);
    font-size: 0.6rem;
}

.ribbon-right a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.ribbon-right a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.ribbon-right i {
    margin-right: 4px;
}

@media (max-width: 700px) {
    .header-ribbon {
        flex-direction: column;
        text-align: center;
    }

    .ribbon-left {
        align-items: center;
    }

    .ribbon-right {
        flex-wrap: wrap;
        justify-content: center;
    }
}

h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    margin: 0 0 1rem;
    padding-bottom: 0.75rem;
    border-bottom: 2px solid var(--border-light);
    display: flex;
    align-items: center;
    gap: 8px;
}

h2::before {
    content: '';
    width: 4px;
    height: 20px;
    background: var(--primary-gradient);
    border-radius: 2px;
}

/* --- Layout Grid --- */
.layout {
    display: grid;
    grid-template-columns: minmax(360px, 1fr) minmax(400px, 1.4fr);
    gap: 2rem;
    align-items: flex-start;
    margin-top: 1.5rem;
}

.left-panel,
.right-panel {
    min-width: 0;
}

@media (max-width: 1000px) {
    .layout {
        grid-template-columns: 1fr;
    }

    .right-panel {
        margin-top: 1.5rem;
    }
}

/* --- Glass Panel Effect --- */
form {
    background: var(--surface-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: var(--radius-xl);
    padding: 1.75rem;
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(255, 255, 255, 0.6);
    margin-top: 1rem;
    transition: box-shadow var(--transition-smooth);
}

form:hover {
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

/* --- Fieldsets --- */
.form-grid fieldset {
    border: 1px solid var(--border-light);
    border-radius: var(--radius-md);
    margin-bottom: 1.25rem;
    padding: 1.25rem 1.25rem 0.75rem;
    background: rgba(255, 255, 255, 0.5);
    transition: all var(--transition-smooth);
}

.form-grid fieldset:hover {
    border-color: var(--accent-color);
    background: rgba(255, 255, 255, 0.7);
}

.form-grid legend {
    padding: 0.25rem 0.75rem;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--accent-color);
    background: var(--accent-light);
    border-radius: 20px;
    letter-spacing: 0.02em;
}

/* --- Form Labels & Inputs --- */
.form-grid label {
    display: flex;
    flex-direction: column;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.9rem;
    transition: color var(--transition-fast);
}

.form-grid label:hover {
    color: var(--text-primary);
}

.form-grid input[type="text"],
.form-grid input[type="number"],
.form-grid select {
    margin-top: 0.35rem;
    padding: 0.6rem 0.75rem;
    border-radius: var(--radius-sm);
    border: 1.5px solid var(--border-subtle);
    font-size: 0.9rem;
    background: var(--surface-solid);
    color: var(--text-primary);
    transition: all var(--transition-fast);
}

.form-grid input:focus,
.form-grid select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px var(--accent-light);
}

.form-grid input:hover,
.form-grid select:hover {
    border-color: var(--accent-color);
}

/* --- Checkboxes --- */
.checkbox {
    flex-direction: row !important;
    align-items: center;
    cursor: pointer;
    padding: 0.5rem 0;
}

.checkbox input[type="checkbox"] {
    appearance: none;
    -webkit-appearance: none;
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-subtle);
    border-radius: 6px;
    margin-right: 0.6rem;
    margin-top: 0;
    cursor: pointer;
    position: relative;
    transition: all var(--transition-fast);
    background: var(--surface-solid);
}

.checkbox input[type="checkbox"]:checked {
    background: var(--primary-gradient);
    border-color: var(--accent-color);
}

.checkbox input[type="checkbox"]:checked::after {
    content: '✓';
    position: absolute;
    color: white;
    font-size: 12px;
    font-weight: bold;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.checkbox input[type="checkbox"]:hover {
    border-color: var(--accent-color);
}

/* --- Hints --- */
.hint {
    display: block;
    font-size: 0.78rem;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
    font-style: italic;
}

/* --- Buttons --- */
.actions {
    text-align: right;
    margin-top: 1.25rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-subtle);
}

button {
    background: var(--primary-gradient);
    border: none;
    color: white;
    padding: 0.75rem 2rem;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-smooth);
    box-shadow: var(--shadow-md);
    position: relative;
    overflow: hidden;
}

button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left 0.5s ease;
}

button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg), var(--shadow-glow);
}

button:hover::before {
    left: 100%;
}

button:active {
    transform: translateY(0);
}

button:disabled {
    background: linear-gradient(135deg, #a0aec0 0%, #718096 100%);
    cursor: not-allowed;
    transform: none;
    box-shadow: var(--shadow-sm);
}

/* --- Alerts --- */
.alert {
    padding: 1rem 1.25rem;
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 10px;
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.alert-error {
    background: linear-gradient(135deg, #fff5f5 0%, #fed7d7 100%);
    border: 1px solid var(--error);
    color: #c53030;
}

.alert-error::before {
    content: '⚠';
    font-size: 1.2rem;
}

/* --- Info Box --- */
.info-box {
    background: linear-gradient(135deg, #ebf8ff 0%, #e6fffa 100%);
    border: 1px solid var(--info);
    padding: 1rem 1.25rem;
    border-radius: var(--radius-md);
    white-space: pre-wrap;
    font-size: 0.85rem;
    font-family: 'JetBrains Mono', 'Fira Code', monospace;
    margin-top: 1rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

/* --- Results Section --- */
.right-panel>h2 {
    margin-bottom: 1rem;
}

.no-results {
    font-size: 0.95rem;
    color: var(--text-muted);
    text-align: center;
    padding: 3rem 1rem;
    background: var(--surface-glass);
    border-radius: var(--radius-lg);
    border: 2px dashed var(--border-light);
}

/* --- Plots Grid --- */
.plots {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
    margin-top: 0.5rem;
}

.plot-card {
    background: var(--surface-glass);
    backdrop-filter: blur(12px);
    border-radius: var(--radius-lg);
    padding: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid rgba(255, 255, 255, 0.6);
    transition: all var(--transition-smooth);
}

.plot-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.plot-container {
    position: relative;
    display: block;
    cursor: crosshair;
}

.plot-container img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: var(--radius-sm);
    transition: filter var(--transition-smooth);
}

.plot-container:hover img {
    filter: brightness(1.02);
}

/* --- Coordinate Tooltip --- */
.coord-tooltip {
    position: absolute;
    display: none;
    background: rgba(26, 32, 44, 0.95);
    backdrop-filter: blur(8px);
    color: #fff;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-family: 'JetBrains Mono', monospace;
    pointer-events: none;
    z-index: 100;
    white-space: nowrap;
    line-height: 1.5;
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(102, 126, 234, 0.3);
}

.coord-tooltip strong {
    color: #a5b4fc;
    font-weight: 600;
}

/* --- Loading Indicator --- */
.loading-box {
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #e0e7ff 0%, #c7d2fe 100%);
    border: 1px solid var(--accent-color);
    color: var(--accent-color);
    padding: 1.25rem;
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
    font-weight: 600;
    font-size: 0.95rem;
    animation: pulse 2s infinite;
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.8;
    }
}

.spinner {
    border: 3px solid rgba(102, 126, 234, 0.2);
    border-left-color: var(--accent-color);
    border-radius: 50%;
    width: 24px;
    height: 24px;
    animation: spin 0.8s linear infinite;
    margin-right: 14px;
}

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

    100% {
        transform: rotate(360deg);
    }
}

/* --- Info Section (Author/Source) --- */
.info-section {
    text-align: center;
    margin: 0.5rem 0 1.5rem;
    padding: 1rem;
    background: var(--surface-glass);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-lg);
    font-size: 0.9rem;
    color: var(--text-secondary);
    border: 1px solid rgba(255, 255, 255, 0.6);
}

.info-section p {
    margin: 0;
}

.info-separator {
    margin: 0 12px;
    color: var(--border-subtle);
}

.info-section a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
    transition: all var(--transition-fast);
    position: relative;
}

.info-section a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-gradient);
    transition: width var(--transition-smooth);
}

.info-section a:hover::after {
    width: 100%;
}

.info-section a:hover {
    color: var(--accent-hover);
}

.info-section i {
    margin-right: 5px;
    color: var(--text-muted);
}

/* --- Gamma Display Box --- */
#gamma-display {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
    color: var(--accent-color);
    background: var(--accent-light);
    padding: 2px 8px;
    border-radius: 4px;
}

/* --- KaTeX Formula Styling --- */
.katex {
    font-size: 0.95em;
}

/* --- Responsive Adjustments --- */
@media (max-width: 600px) {
    .container {
        padding: 1rem;
    }

    h1 {
        font-size: 1.75rem;
    }

    form {
        padding: 1.25rem;
        border-radius: var(--radius-lg);
    }

    button {
        width: 100%;
        padding: 0.9rem;
    }

    .info-separator {
        display: block;
        margin: 8px auto;
        width: 30px;
        height: 1px;
        background: var(--border-subtle);
        color: transparent;
    }

    .author-info,
    .source-info {
        display: block;
    }
}

/* --- Scrollbar Styling --- */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-base);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-light);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-color);
}

/* --- Selection Color --- */
::selection {
    background: var(--accent-light);
    color: var(--accent-color);
}

/* --- N Input Superscript Styling --- */
.n-input-group {
    display: flex;
    align-items: center;
    margin-bottom: 0.5rem;
    font-size: 1rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.n-label {
    margin-right: 2px;
}

.nsup-wrapper {
    position: relative;
    top: -8px;
    /* Move up for superscript effect */
}

.nsup-wrapper input[type="number"] {
    width: 60px;
    padding: 2px 4px;
    font-size: 0.85rem;
    height: auto;
    margin: 0;
    text-align: center;
    border-radius: 4px;

}