:root{--bg:#195f5a;--bg-strong:#134d49;--panel:rgba(21,86,81,0.78);--panel-strong:rgba(17,72,68,0.96);--ink:#f8fcfb;--muted:#d0e7e3;--line:rgba(203,238,232,0.16);--accent:#1fa39a;--accent-strong:#167f78;--accent-soft:rgba(31,163,154,0.18);--accent-deep:#9df0e6;--accent-warm:#ff7a16;--accent-warm-soft:rgba(255,122,22,0.18);--danger:#ffb4b4;--danger-bg:rgba(118,30,30,0.3);--shadow:0 24px 70px rgba(6,36,34,0.34);--field-bg:rgba(12,68,64,0.94);--field-border:rgba(203,238,232,0.22);--chip-bg:linear-gradient(135deg,rgba(31,163,154,0.22),rgba(18,105,99,0.9));--chip-hover-bg:linear-gradient(135deg,rgba(74,196,186,0.28),rgba(18,117,110,0.94));--chip-selected-bg:linear-gradient(135deg,rgba(255,142,50,0.96),rgba(240,114,19,0.92));--chip-selected-border:rgba(255,176,96,0.58);--chip-text:#eef9f7;--chip-selected-text:#fffaf3}:root[data-theme=light]{--bg:#edf8f6;--bg-strong:#d7eeea;--panel:rgba(255,255,255,0.88);--panel-strong:rgba(244,252,250,0.96);--ink:#174b47;--muted:#486763;--line:rgba(23,75,71,0.18);--accent:#1a8f87;--accent-strong:#136d67;--accent-soft:rgba(26,143,135,0.12);--accent-deep:#0f5b56;--accent-warm:#f47a20;--accent-warm-soft:rgba(244,122,32,0.12);--danger:#7f1d1d;--danger-bg:rgba(254,242,242,0.94);--shadow:0 24px 70px rgba(18,92,86,0.12);--field-bg:rgba(255,255,255,0.98);--field-border:rgba(23,75,71,0.16);--chip-bg:linear-gradient(135deg,rgba(222,247,239,0.98),rgba(234,251,246,0.98));--chip-hover-bg:linear-gradient(135deg,rgba(175,232,216,0.98),rgba(226,248,241,0.98));--chip-selected-bg:linear-gradient(135deg,rgba(255,229,204,0.98),rgba(255,244,231,0.98));--chip-selected-border:rgba(244,122,32,0.34);--chip-text:#174b47;--chip-selected-text:#8f460f}*{box-sizing:border-box}html{min-height:100%}body{margin:0;min-height:100vh;color:var(--ink);font-family:var(--font-body),sans-serif;background:radial-gradient(circle at 78% 14%,rgba(31,163,154,.26),transparent 16%),radial-gradient(circle at top left,rgba(11,95,88,.28),transparent 32%),radial-gradient(circle at bottom right,rgba(255,122,22,.12),transparent 26%),linear-gradient(180deg,#185a56 0,var(--bg) 52%,#124944 100%)}:root[data-theme=light] body{background:radial-gradient(circle at 82% 12%,rgba(31,163,154,.16),transparent 14%),radial-gradient(circle at 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10px;letter-spacing:.14em;text-transform:uppercase;font-size:.76rem;color:var(--accent-warm)}.empty-state h2,.intro-band h1,.workspace-main h1,.workspace-sidebar h2{margin:0;font-family:var(--font-display),sans-serif;line-height:1.02}.intro-band h1{max-width:760px;font-size:clamp(2.6rem,5vw,4.4rem);color:#ffffff;text-shadow:0 10px 30px rgba(8,42,39,.18)}:root[data-theme=light] .intro-band h1{color:var(--accent-deep);text-shadow:none}.intro-copy,.lead,.muted{color:var(--muted)}.intro-copy{max-width:660px;margin:10px 0 0;font-size:1rem;line-height:1.6}.landing-options{max-width:1100px;margin:0 auto;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));grid-gap:22px;gap:22px}.landing-hero-upgraded{display:grid;grid-template-columns:minmax(0,1.2fr) 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h2{font-size:clamp(1.6rem,3vw,2.3rem)}.auth-stage{max-width:1220px;min-height:calc(100vh - 180px);margin:0 auto;display:grid;grid-template-columns:minmax(0,1.05fr) minmax(360px,460px);grid-gap:48px;gap:48px;align-items:center}.auth-showcase{min-height:540px;display:flex;align-items:center}.auth-copy-stack{max-width:600px;display:grid;grid-gap:22px;gap:22px}.auth-brand-mark{font-size:clamp(3rem,7vw,5.5rem);font-weight:700;letter-spacing:-.04em;line-height:.92;text-shadow:0 18px 44px rgba(7,35,33,.22)}.auth-brand-mark,.auth-showcase h1{margin:0;color:#ffffff;font-family:var(--font-display),sans-serif}.auth-showcase h1{max-width:11ch;font-size:clamp(2.9rem,6vw,5rem);line-height:.94}.auth-showcase-copy{margin:0;max-width:560px;color:var(--muted);font-size:1.18rem;line-height:1.75}:root[data-theme=light] .auth-brand-mark,:root[data-theme=light] .auth-showcase h1{color:var(--accent-deep);text-shadow:none}:root[data-theme=light] .landing-spotlight{background:linear-gradient(180deg,rgba(255,255,255,.98),rgba(241,250,248,.95))}.auth-login-card{width:min(100%,460px);justify-self:end;padding:28px;border-radius:30px;background:linear-gradient(180deg,rgba(22,96,90,.98),rgba(17,73,68,.95))}:root[data-theme=light] .auth-login-card{background:linear-gradient(180deg,rgba(255,255,255,.98),rgba(243,251,249,.96))}.auth-card-copy{display:grid;grid-gap:8px;gap:8px;margin-bottom:4px}.auth-card-copy h2{margin:0;font-family:var(--font-display),sans-serif;font-size:clamp(1.8rem,4vw,2.4rem);line-height:1.02}.auth-story-sections{max-width:1220px;margin:38px auto 0;display:grid;grid-gap:34px;gap:34px}.auth-story-line{display:grid;grid-gap:10px;gap:10px;max-width:920px;padding-left:26px;border-left:2px solid rgba(203,238,232,.16)}.auth-story-line h3{margin:0;font-family:var(--font-display),sans-serif;font-size:clamp(1.65rem,3vw,2.35rem);line-height:1.08}.auth-story-quote{max-width:900px;margin:2px auto;padding:12px 0;text-align:center}.auth-story-quote-mark{display:inline;color:var(--accent-warm);font-size:1.1em;line-height:1}.auth-story-quote p{margin:0 auto;max-width:22ch;font-family:var(--font-display),sans-serif;font-size:clamp(1.7rem,3.6vw,2.7rem);line-height:1.12;color:var(--ink)}.auth-story-attribution{display:inline-block;margin-top:12px;color:var(--muted);font-size:1rem;letter-spacing:.02em}.landing-card{min-height:260px;text-decoration:none;display:grid;align-content:end;grid-gap:12px;gap:12px;padding:30px}.landing-card h2{margin:0;font-family:var(--font-display),sans-serif;font-size:clamp(2rem,3vw,3rem)}.landing-options-upgraded .landing-card{min-height:320px}.landing-card-primary{background:radial-gradient(circle at top right,rgba(255,122,22,.12),transparent 28%),linear-gradient(180deg,rgba(19,89,83,.96),rgba(16,74,69,.92))}.landing-card-secondary{background:radial-gradient(circle at top left,rgba(31,163,154,.18),transparent 26%),linear-gradient(180deg,rgba(17,79,75,.92),rgba(14,66,62,.9))}:root[data-theme=light] .landing-card-primary,:root[data-theme=light] .landing-card-secondary{background:linear-gradient(180deg,rgba(255,255,255,.98),rgba(241,250,248,.95))}.landing-link-row{display:inline-flex;align-items:center;gap:8px;margin-top:8px;color:var(--accent-deep);font-weight:700}.flow-shell,.result-page-shell{max-width:1100px;margin:0 auto;display:grid;grid-gap:22px;gap:22px}.centered-form{max-width:820px;margin:0 auto}.flow-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));grid-gap:14px;gap:14px}.flow-actions{display:flex;justify-content:center}.flow-actions-between{justify-content:space-between;align-items:center}.flow-actions-end{justify-content:flex-end}.compact-error{padding:14px 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var(--line);border-radius:28px;background:var(--panel);box-shadow:var(--shadow);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}.interactive-card{transition:transform .18s ease,box-shadow .18s ease,border-color .18s ease,background .18s ease}.interactive-card:hover{transform:translateY(-3px);border-color:rgba(31,163,154,.44);box-shadow:0 28px 80px rgba(8,42,39,.34);background:rgba(20,93,87,.98)}:root[data-theme=light] .interactive-card:hover{border-color:rgba(26,143,135,.28);box-shadow:0 28px 80px rgba(18,92,86,.14);background:rgba(255,255,255,.94)}.content-card-accent,.panel-highlight{background:linear-gradient(180deg,rgba(22,95,89,.96),rgba(18,78,73,.9))}:root[data-theme=light] .content-card-accent,:root[data-theme=light] .panel-highlight{background:linear-gradient(180deg,rgba(245,249,255,.96),rgba(255,250,245,.88))}.hero-output{padding:28px}.hero-output h1{font-size:clamp(2rem,4vw,3.2rem)}.lead{max-width:680px;margin:16px 0 0;font-size:1rem;line-height:1.75}.stat-row,.summary-panel{display:flex;align-items:center;justify-content:space-between;gap:12px}.stat-row+.stat-row{margin-top:10px}.form-panel{display:grid;grid-gap:16px;gap:16px}.form-panel fieldset,.form-panel label{display:grid;grid-gap:8px;gap:8px}.form-panel fieldset{padding:14px;margin:0;border:1px solid var(--line);border-radius:20px;background:rgba(255,255,255,.02)}.form-panel legend{padding:0 8px;font-weight:600;color:var(--accent-deep)}.form-panel input,.form-panel select,.form-panel textarea{min-height:48px;padding:0 14px;border:1px solid var(--field-border);border-radius:14px;background:var(--field-bg);color:var(--ink)}.stepper-control{min-height:48px;display:grid;grid-template-columns:48px 1fr 48px;align-items:center;border:1px solid var(--field-border);border-radius:16px;background:var(--field-bg);overflow:hidden}.form-panel .stepper-button{min-height:48px;border:0;border-radius:0;background:transparent;color:var(--accent-deep);font-family:var(--font-display),sans-serif;font-size:1.5rem;line-height:1;cursor:pointer;box-shadow:none;transition:color .16s ease,background .16s ease}.form-panel .stepper-button:hover{background:transparent;color:var(--accent);transform:none;box-shadow:none}.stepper-value{text-align:center;font-weight:700;color:var(--ink)}.form-panel select{-webkit-appearance:none;-moz-appearance:none;appearance:none;padding-right:44px;background-image:linear-gradient(45deg,transparent 50%,var(--accent-deep) 50%),linear-gradient(135deg,var(--accent-deep) 50%,transparent 50%);background-position:calc(100% - 22px) calc(50% - 3px),calc(100% - 16px) calc(50% - 3px);background-size:6px 6px,6px 6px;background-repeat:no-repeat}.form-panel input::placeholder,.form-panel textarea::placeholder{color:var(--muted)}.chapter-chip:focus,.form-panel input[type=number]:focus,.form-panel select:focus,.form-panel 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.chapter-chip{width:100%;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:14px 16px;border-radius:16px;border:1px solid var(--field-border);background:var(--chip-bg);color:var(--chip-text);cursor:pointer;transition:transform .16s ease,border-color .16s ease,background .16s ease,box-shadow .16s ease}.form-panel .chapter-chip:hover{transform:translateY(-1px);border-color:rgba(31,163,154,.42);background:var(--chip-hover-bg)}.form-panel .chapter-chip.is-selected{border-color:var(--chip-selected-border);background:var(--chip-selected-bg);box-shadow:inset 0 0 0 1px rgba(255,201,145,.2);color:var(--chip-selected-text)}.form-panel .chapter-chip-mark{min-width:18px;text-align:right;color:var(--accent-deep);font-weight:700}.form-panel .chapter-chip.is-selected .chapter-chip-mark{color:var(--chip-selected-text)}.form-panel button{min-height:54px;border:0;border-radius:18px;color:#f8fbff;background:linear-gradient(135deg,var(--accent-warm),#ff8e32 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20px;border:1px solid var(--line);border-radius:22px;background:rgba(18,79,74,.92)}:root[data-theme=light] .content-card{background:rgba(255,255,255,.84)}.action-copy{display:flex;gap:10px;flex-wrap:wrap}.ghost-button{min-height:42px;padding:0 14px;border:1px solid var(--line);border-radius:14px;background:var(--panel-strong);color:var(--ink);cursor:pointer;transition:border-color .16s ease,background .16s ease,color .16s ease,transform .16s ease}.ghost-button:hover{transform:translateY(-1px);border-color:rgba(31,163,154,.44);background:rgba(31,163,154,.12)}:root[data-theme=light] .ghost-button:hover{background:rgba(26,143,135,.08)}.history-list{display:grid;grid-gap:12px;gap:12px}.history-card{width:100%;padding:14px 16px;border:1px solid var(--line);border-radius:18px;background:rgba(18,79,74,.92);text-align:left;display:grid;grid-gap:4px;gap:4px;cursor:pointer}:root[data-theme=light] .history-card{background:rgba(255,255,255,.76)}.history-card span{color:var(--muted);font-size:.92rem}.theme-row{display:flex;align-items:flex-start;justify-content:space-between;gap:14px}.compact-theme-panel{padding:14px}.theme-toggle{position:relative}.theme-icon{width:24px;height:24px;color:var(--accent-deep);transition:color .16s ease,filter .16s ease}.theme-icon-light{color:var(--accent-warm);filter:drop-shadow(0 0 8px rgba(255,160,64,.35))}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.auth-submit{min-width:100%;display:inline-flex;align-items:center;justify-content:center;line-height:1}.result-section-label{margin:0 0 10px;color:var(--accent-warm);font-weight:700;letter-spacing:.08em;text-transform:uppercase}.result-line-title{margin:0 0 10px;color:var(--ink);font-weight:700;font-size:1.04rem}.result-line{margin:0 0 8px;color:var(--ink);line-height:1.65}.result-math-inline{display:inline-block;max-width:100%;vertical-align:middle}.result-math-block{display:block;width:100%;max-width:100%;overflow-x:auto;overflow-y:hidden}.result-math-block-only{margin:10px 0 14px}.result-line .katex-display,.result-math-block .katex-display{margin:.6em 0;overflow-x:auto;overflow-y:hidden}.result-line .katex{max-width:100%}.option-line strong{color:var(--accent)}.empty-state{min-height:280px;display:grid;align-content:center}.error-panel{color:var(--danger);background:var(--danger-bg);border-color:rgba(237,125,49,.18)}@media (max-width:980px){.workspace-shell{grid-template-columns:1fr}.intro-band{padding:26px}.flow-grid,.landing-options{grid-template-columns:1fr}.answer-cta,.auth-stage,.flow-intro,.landing-hero{align-items:flex-start;flex-direction:column}.auth-stage,.landing-hero-upgraded{grid-template-columns:1fr}.auth-stage{gap:24px}.auth-showcase,.auth-stage{min-height:auto}.auth-login-card{justify-self:stretch}.auth-story-line{padding-left:20px}}@media (max-width:640px){.page-shell{padding:20px 14px 60px}.auth-page-shell{padding:92px 14px 40px}.history-header,.result-actions,.split-fields{grid-template-columns:1fr;display:grid}.intro-band,.panel{border-radius:24px;padding:18px}.intro-band h1{font-size:2.45rem}.site-header-inner{padding:12px 16px}.auth-showcase h1{max-width:12ch;font-size:2.8rem}.auth-showcase-copy{font-size:1rem}.auth-story-line{padding-left:16px}.auth-story-quote p{max-width:100%}}