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

:root {
    --color-bg: #f8f9fb;
    --color-surface: #ffffff;
    --color-border: #e2e5ea;
    --color-border-light: #eef0f3;
    --color-text: #1a1d23;
    --color-text-secondary: #6b7280;
    --color-text-muted: #9ca3af;
    --color-primary: #be123c;
    --color-primary-hover: #9f1239;
    --color-primary-light: #fff1f2;
    --color-primary-border: #fecdd3;
    --color-success: #059669;
    --color-success-light: #ecfdf5;
    --color-success-border: #a7f3d0;
    --color-warning: #d97706;
    --color-warning-light: #fffbeb;
    --color-warning-border: #fde68a;
    --color-danger: #ea580c;
    --color-danger-light: #fff7ed;
    --color-danger-border: #fed7aa;
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 18px;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.08);
    --shadow-xl: 0 8px 32px rgba(0, 0, 0, 0.1);
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    height: 100%;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    height: 100%;
    display: flex;
    flex-direction: column;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.hidden {
    display: none !important;
}

/* ───── Header ───── */

header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 0 24px;
    height: 60px;
    flex-shrink: 0;
    z-index: 20;
}

.header-inner {
    max-width: 1600px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--color-primary);
}

.logo h1 {
    font-size: 18px;
    font-weight: 800;
    color: var(--color-text);
    letter-spacing: -0.02em;
}

.style-selector {
    display: flex;
    align-items: center;
    gap: 10px;
}

.style-selector label {
    font-size: 12px;
    font-weight: 700;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.style-pills {
    display: flex;
    background: var(--color-bg);
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 3px;
    gap: 2px;
}

.style-pill {
    font-family: inherit;
    font-size: 13px;
    font-weight: 600;
    color: var(--color-text-secondary);
    background: transparent;
    border: none;
    border-radius: calc(var(--radius-md) - 3px);
    padding: 6px 14px;
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
}

.style-pill:hover:not(.active) {
    color: var(--color-text);
    background: var(--color-surface);
}

.style-pill.active {
    background: var(--color-primary);
    color: #fff;
    box-shadow: 0 1px 3px rgba(190, 18, 60, 0.3);
}

.style-selector select {
    font-family: inherit;
    font-size: 13px;
    font-weight: 500;
    color: var(--color-text);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 6px 28px 6px 10px;
    cursor: pointer;
    outline: none;
    transition: border-color var(--transition);
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg width='10' height='6' viewBox='0 0 10 6' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1L5 5L9 1' stroke='%236b7280' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 8px center;
}

.style-selector select:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(190, 18, 60, 0.1);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 16px;
}

.upgrade-btn {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 7px 14px;
    font-family: inherit;
    font-size: 13px;
    font-weight: 600;
    color: var(--color-primary);
    background: var(--color-primary-light);
    border: 1.5px solid var(--color-primary-border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all var(--transition);
    white-space: nowrap;
}

.upgrade-btn:hover {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

.account-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--color-surface);
    border: 1.5px solid var(--color-border);
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--transition);
}

.account-btn:hover {
    color: var(--color-primary);
    border-color: var(--color-primary-border);
    background: var(--color-primary-light);
}

.account-btn.logged-in {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}

/* ───── Main Layout ───── */

main {
    flex: 1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    min-height: 0;
    max-width: 1600px;
    margin: 0 auto;
    width: 100%;
}

.panel-header {
    padding: 20px 24px 0;
    display: flex;
    align-items: baseline;
    gap: 12px;
}

.panel-header h2 {
    font-size: 14px;
    font-weight: 700;
    color: var(--color-text);
    text-transform: uppercase;
    letter-spacing: 0.04em;
}

.panel-hint {
    font-size: 13px;
    color: var(--color-text-muted);
}

/* ───── Input Panel ───── */

.input-panel {
    display: flex;
    flex-direction: column;
    border-right: 1px solid var(--color-border);
    background: var(--color-surface);
}

#text-input {
    flex: 1;
    margin: 16px 24px;
    padding: 16px 20px;
    background: var(--color-bg);
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-lg);
    font-family: inherit;
    font-size: 15px;
    line-height: 1.7;
    color: var(--color-text);
    outline: none;
    overflow-y: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
    transition: border-color var(--transition), box-shadow var(--transition);
    cursor: text;
}

#text-input:focus {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(190, 18, 60, 0.08);
}

#text-input:empty::before {
    content: attr(placeholder);
    color: var(--color-text-muted);
    pointer-events: none;
}

#text-input .claim-highlight {
    background: rgba(190, 18, 60, 0.08);
    color: var(--color-text);
    border-radius: 4px;
    padding: 1px 4px;
    cursor: pointer;
    transition: all var(--transition);
    border-bottom: 2px solid rgba(190, 18, 60, 0.3);
}

#text-input .claim-highlight:hover {
    background: rgba(190, 18, 60, 0.14);
    border-bottom-color: var(--color-primary);
}

#text-input .claim-highlight.active {
    background: var(--color-primary-light);
    border-bottom-color: var(--color-primary);
    font-weight: 500;
}

.input-actions {
    padding: 0 24px 20px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

/* ───── Buttons ───── */

.btn-primary {
    flex: 1;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background: var(--color-primary);
    color: #fff;
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    padding: 12px 20px;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: 0 1px 3px rgba(190, 18, 60, 0.3);
}

.btn-primary:hover:not(:disabled) {
    background: var(--color-primary-hover);
    box-shadow: 0 2px 8px rgba(190, 18, 60, 0.35);
    transform: translateY(-1px);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
}

.btn-primary:disabled {
    opacity: 0.55;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.btn-primary.loading span {
    display: none;
}

.btn-primary.loading::after {
    content: 'Analyzing…';
}

.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    background: var(--color-surface);
    color: var(--color-text-secondary);
    font-family: inherit;
    font-size: 14px;
    font-weight: 600;
    padding: 12px 20px;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
}

.btn-secondary:hover {
    background: var(--color-bg);
    border-color: var(--color-text-muted);
    color: var(--color-text);
}

.header-left-group {
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-disclaimer {
    font-size: 10px;
    color: var(--color-text-muted);
    line-height: 1.3;
    max-width: 280px;
}

/* ───── Results Panel ───── */

.results-panel {
    display: flex;
    flex-direction: column;
    background: var(--color-bg);
    overflow: hidden;
}

#results-container {
    flex: 1;
    overflow-y: auto;
    padding: 16px 24px 24px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

/* ───── State Messages ───── */

.state-message {
    flex: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 40px 32px;
    text-align: center;
}

.state-icon {
    width: 56px;
    height: 56px;
    border-radius: 50%;
    background: var(--color-primary-light);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
}

.state-icon-success {
    background: var(--color-success-light);
    color: var(--color-success);
}

.state-title {
    font-size: 16px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 6px;
}

.state-desc {
    font-size: 14px;
    color: var(--color-text-muted);
    max-width: 320px;
    line-height: 1.5;
}

.state-desc strong {
    color: var(--color-primary);
    font-weight: 600;
}

/* ───── Spinner ───── */

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--color-border-light);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    margin-bottom: 16px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ───── Reference Cards ───── */

.ref-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    overflow: visible;
    flex-shrink: 0;
    transition: box-shadow var(--transition), border-color var(--transition);
    cursor: pointer;
    animation: cardIn 0.3s ease-out both;
}

.ref-card:hover {
    box-shadow: var(--shadow-md);
    border-color: var(--color-primary-border);
}

@keyframes cardIn {
    from {
        opacity: 0;
        transform: translateY(8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.ref-front,
.ref-back {
    padding: 20px;
    border-radius: var(--radius-lg);
}

.ref-back {
    background: var(--color-bg);
}

.ref-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 10px;
}

.ref-type {
    font-size: 11px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--color-primary);
    background: var(--color-primary-light);
    border: 1px solid var(--color-primary-border);
    padding: 3px 8px;
    border-radius: 100px;
}

.ref-source-name {
    font-size: 12px;
    color: var(--color-text-muted);
    font-weight: 500;
}

.ref-confidence {
    font-size: 11px;
    font-weight: 700;
    padding: 3px 8px;
    border-radius: 100px;
    border: 1px solid;
}

.confidence-high {
    color: var(--color-success);
    background: var(--color-success-light);
    border-color: var(--color-success-border);
}

.confidence-med {
    color: var(--color-warning);
    background: var(--color-warning-light);
    border-color: var(--color-warning-border);
}

.confidence-low {
    color: var(--color-danger);
    background: var(--color-danger-light);
    border-color: var(--color-danger-border);
}

.ref-title {
    font-size: 16px;
    font-weight: 700;
    line-height: 1.35;
    color: var(--color-text);
    margin-bottom: 4px;
}

.ref-authors {
    font-size: 13px;
    color: var(--color-text-secondary);
    font-weight: 500;
    margin-bottom: 14px;
}

.ref-excerpt {
    background: var(--color-bg);
    border-left: 3px solid var(--color-primary);
    padding: 12px 14px;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    margin-bottom: 14px;
}

.ref-excerpt-label {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--color-text-muted);
    margin-bottom: 6px;
}

.ref-excerpt-text {
    font-size: 13px;
    line-height: 1.55;
    color: var(--color-text-secondary);
    font-style: italic;
}

.ref-footer {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 14px;
    border-top: 1px solid var(--color-border-light);
}

.ref-link {
    font-size: 13px;
    font-weight: 600;
    color: var(--color-primary);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    transition: color var(--transition);
}

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

.ref-flip-hint {
    font-size: 12px;
    color: var(--color-text-muted);
    font-weight: 500;
    transition: color var(--transition);
}

.ref-card:hover .ref-flip-hint {
    color: var(--color-primary);
}

/* ───── Card Back ───── */

.citation-section {
    margin-bottom: 16px;
}

.citation-section:last-of-type {
    margin-bottom: 0;
}

.citation-label {
    font-size: 12px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.citation-style-badge {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.06em;
    color: var(--color-primary);
    background: var(--color-primary-light);
    padding: 2px 7px;
    border-radius: 4px;
}

.citation-box {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 12px;
}

.citation-text {
    flex: 1;
    font-size: 13px;
    font-family: 'SF Mono', 'Fira Code', 'Cascadia Code', monospace;
    line-height: 1.55;
    color: var(--color-text-secondary);
    word-break: break-word;
    user-select: all;
}

.copy-btn {
    flex-shrink: 0;
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text-muted);
    cursor: pointer;
    transition: all var(--transition);
}

.copy-btn:hover {
    color: var(--color-primary);
    border-color: var(--color-primary-border);
    background: var(--color-primary-light);
}

.copy-btn.copied {
    color: var(--color-success);
    border-color: var(--color-success-border);
    background: var(--color-success-light);
}

.ref-back-return {
    text-align: center;
    font-size: 12px;
    font-weight: 600;
    color: var(--color-text-muted);
    margin-top: 16px;
    padding-top: 14px;
    border-top: 1px solid var(--color-border-light);
    transition: color var(--transition);
}

.ref-card:hover .ref-back-return {
    color: var(--color-primary);
}

/* ───── No References State ───── */

.no-refs {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 40px 24px;
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-lg);
    background: var(--color-surface);
}

.no-refs-icon {
    width: 48px;
    height: 48px;
    color: var(--color-text-muted);
    margin-bottom: 12px;
    opacity: 0.5;
}

.no-refs-title {
    font-size: 15px;
    font-weight: 700;
    color: var(--color-text-secondary);
    margin-bottom: 4px;
}

.no-refs-desc {
    font-size: 13px;
    color: var(--color-text-muted);
    max-width: 300px;
    line-height: 1.5;
}

/* ───── Toast ───── */

#toast-container {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: 100;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.toast {
    background: var(--color-text);
    color: #fff;
    padding: 12px 18px;
    border-radius: var(--radius-md);
    font-size: 13px;
    font-weight: 500;
    box-shadow: var(--shadow-xl);
    animation: toastIn 0.3s ease-out, toastOut 0.3s ease-in 3.7s forwards;
    max-width: 360px;
}

.toast-error {
    background: #dc2626;
}

@keyframes toastIn {
    from {
        opacity: 0;
        transform: translateY(12px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

@keyframes toastOut {
    from {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
    to {
        opacity: 0;
        transform: translateY(12px) scale(0.95);
    }
}

/* ───── Responsive ───── */

@media (max-width: 900px) {
    main {
        grid-template-columns: 1fr;
        grid-template-rows: 1fr 1fr;
    }

    .input-panel {
        border-right: none;
        border-bottom: 1px solid var(--color-border);
    }

    .panel-hint {
        display: none;
    }
}

@media (max-width: 600px) {
    header {
        padding: 0 16px;
    }

    .style-pills {
        display: none;
    }

    .style-selector select.hidden {
        display: block !important;
    }

    .style-selector label {
        display: none;
    }

    .panel-header {
        padding: 16px 16px 0;
    }

    #text-input {
        margin: 12px 16px;
        padding: 14px 16px;
    }

    .input-actions {
        padding: 0 16px 16px;
    }

    #results-container {
        padding: 12px 16px 16px;
    }

    .ref-front,
    .ref-back {
        padding: 16px;
    }

    .logo h1 {
        font-size: 16px;
    }

    .header-disclaimer {
        display: none; /* Prevent overlapping on small mobile screens */
    }
}

/* ───── Scrollbar ───── */

::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: transparent;
}

::-webkit-scrollbar-thumb {
    background: var(--color-border);
    border-radius: 3px;
}

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

/* ───── Selection ───── */

::selection {
    background: rgba(190, 18, 60, 0.15);
    color: inherit;
}

/* ───── Paywall Modal ───── */

.paywall-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 200;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease-out;
}

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

.paywall-modal {
    background: var(--color-surface);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
    max-width: 440px;
    width: 90%;
    padding: 36px 32px;
    text-align: center;
    animation: modalIn 0.3s ease-out;
}

@keyframes modalIn {
    from { opacity: 0; transform: translateY(16px) scale(0.96); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

.paywall-icon {
    width: 64px;
    height: 64px;
    border-radius: 50%;
    background: var(--color-primary-light);
    color: var(--color-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 20px;
}

.paywall-title {
    font-size: 22px;
    font-weight: 800;
    color: var(--color-text);
    margin-bottom: 8px;
    letter-spacing: -0.02em;
}

.paywall-desc {
    font-size: 14px;
    color: var(--color-text-secondary);
    line-height: 1.6;
    margin-bottom: 28px;
}

.auth-input {
    width: 100%;
    padding: 12px 16px;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-md);
    margin-bottom: 20px;
    font-family: inherit;
    font-size: 15px;
    color: var(--color-text);
    outline: none;
    transition: border-color var(--transition);
}
.auth-input:focus {
    border-color: var(--color-primary);
}

.paywall-plans {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 20px;
}

.paywall-plan {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 18px;
    border: 1.5px solid var(--color-border);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
    background: var(--color-surface);
}

.paywall-plan:hover {
    border-color: var(--color-primary);
    background: var(--color-primary-light);
}

.paywall-plan.selected {
    border-color: var(--color-primary);
    background: var(--color-primary-light);
    box-shadow: 0 0 0 3px rgba(190, 18, 60, 0.1);
}

.paywall-plan-name {
    font-size: 14px;
    font-weight: 700;
    color: var(--color-text);
}

.paywall-plan-detail {
    font-size: 12px;
    color: var(--color-text-muted);
    margin-top: 2px;
}

.paywall-plan-price {
    font-size: 18px;
    font-weight: 800;
    color: var(--color-primary);
}

.paywall-plan-period {
    font-size: 11px;
    color: var(--color-text-muted);
    font-weight: 500;
}

.paywall-cta {
    width: 100%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    background: var(--color-primary);
    color: #fff;
    font-family: inherit;
    font-size: 15px;
    font-weight: 700;
    padding: 14px 20px;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition);
    box-shadow: 0 1px 3px rgba(190, 18, 60, 0.3);
}

.paywall-cta:hover {
    background: var(--color-primary-hover);
    box-shadow: 0 2px 8px rgba(190, 18, 60, 0.35);
    transform: translateY(-1px);
}

.paywall-footer {
    margin-top: 16px;
    font-size: 12px;
    color: var(--color-text-muted);
}

.paywall-disclaimer {
    margin-top: 8px;
    font-size: 11px;
    font-weight: 600;
    color: var(--color-danger);
}

.paywall-usage {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    margin-bottom: 20px;
    font-size: 13px;
    color: var(--color-text-secondary);
    font-weight: 600;
}

.paywall-usage-bar {
    width: 120px;
    height: 6px;
    background: var(--color-border-light);
    border-radius: 3px;
    overflow: hidden;
}

.paywall-usage-fill {
    height: 100%;
    background: var(--color-primary);
    border-radius: 3px;
    width: 100%;
}

.usage-counter {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-md);
    padding: 8px 14px;
    font-size: 12px;
    font-weight: 600;
    color: var(--color-text-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex: 1;
    white-space: nowrap;
}

.usage-counter-bar {
    width: 60px;
    height: 4px;
    background: var(--color-border-light);
    border-radius: 2px;
    overflow: hidden;
}

.usage-counter-fill {
    height: 100%;
    background: var(--color-primary);
    border-radius: 2px;
    transition: width 0.3s ease;
}

.usage-counter-warn {
    color: var(--color-danger);
}

.usage-counter-warn .usage-counter-fill {
    background: var(--color-danger);
}