:root{color-scheme:dark;--ink:#f8f7ff;--muted:#b8b5cc;--panel:#171526;--line:#44405d;--violet:#c5a7ff;--mint:#8ff0cb;--warm:#ffc973}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:radial-gradient(circle at 14% 8%,rgba(197,167,255,.17),transparent 30rem),radial-gradient(circle at 90% 78%,rgba(143,240,203,.1),transparent 28rem),#0b0a13;color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif}button,a{font:inherit}.study-shell{width:min(900px,calc(100% - 28px));margin:auto;padding:28px 0 56px}.back-link{color:var(--violet);text-underline-offset:4px}.study-header{display:flex;justify-content:space-between;gap:28px;align-items:end;margin:42px 0 22px}.eyebrow{margin:0 0 8px;color:var(--violet);font-size:.76rem;font-weight:850;letter-spacing:.14em;text-transform:uppercase}h1{margin:0;font-size:clamp(3.2rem,9vw,6.3rem);line-height:.83;letter-spacing:-.07em}.intro{max-width:44ch;margin:20px 0 0;color:var(--muted);line-height:1.6}.progress-card{min-width:114px;padding:14px 18px;border:1px solid var(--line);border-radius:16px;background:var(--panel);text-align:center}.progress-card span,.progress-card small{display:block;color:var(--muted);font-size:.72rem;font-weight:850;letter-spacing:.12em;text-transform:uppercase}.progress-card strong{display:block;margin:4px 0;color:var(--mint);font:900 2.35rem/1 ui-monospace,monospace}.study-panel{padding:clamp(14px,3vw,28px);border:1px solid var(--line);border-radius:24px;background:linear-gradient(145deg,rgba(30,27,49,.98),rgba(14,13,24,.99));box-shadow:0 28px 70px rgba(0,0,0,.35)}.flash-card{display:grid;place-content:center;min-height:clamp(295px,52vw,430px);padding:32px;border:2px solid rgba(255,255,255,.3);border-radius:22px;background:linear-gradient(135deg,#fcfbff,#dcd4ef);color:#201c32;text-align:center;cursor:pointer;transition:transform .18s ease,background .18s ease,color .18s ease}.flash-card:hover{transform:translateY(-3px)}.flash-card.is-revealed{background:linear-gradient(135deg,#2c2449,#181425);color:#fbfaff;border-color:var(--violet)}.flash-card:focus-visible,.action:focus-visible,.reset-button:focus-visible{outline:3px solid var(--warm);outline-offset:4px}.card-language{margin:0 0 16px;font-size:clamp(1rem,2vw,1.3rem);font-style:italic}.card-word{max-width:100%;margin:0;font-size:clamp(2.5rem,9vw,5.7rem);font-weight:900;line-height:1;letter-spacing:-.06em;overflow-wrap:anywhere}.card-hint{margin:28px 0 0;font-size:.88rem;opacity:.72}.status{min-height:1.5em;margin:16px 0;color:var(--muted);text-align:center}.study-actions{display:grid;grid-template-columns:1fr 1.2fr 1fr;gap:10px}.action{min-height:56px;padding:12px 14px;border:1px solid var(--line);border-radius:14px;font-weight:800;cursor:pointer;transition:transform .18s ease,filter .18s ease}.action:hover{transform:translateY(-2px);filter:brightness(1.08)}.action--secondary{background:#211e32;color:var(--ink)}.action--reveal{background:var(--violet);color:#211736}.action--known{background:var(--mint);color:#09251e}.action:disabled{cursor:not-allowed;filter:grayscale(.8);opacity:.45;transform:none}.reset-button{display:block;margin:16px auto 0;border:0;background:none;color:var(--muted);text-decoration:underline;text-underline-offset:4px;cursor:pointer}.knowledge-check[hidden]{display:none}.knowledge-check{position:fixed;z-index:10;inset:0;display:grid;place-items:center;padding:20px;background:rgba(6,5,12,.78);backdrop-filter:blur(7px)}.check-popup{width:min(560px,100%);padding:clamp(24px,5vw,42px);border:1px solid var(--line);border-radius:24px;background:linear-gradient(145deg,#282143,#14111f);box-shadow:0 28px 80px rgba(0,0,0,.5)}.check-popup h2{margin:0;max-width:17ch;font-size:clamp(1.7rem,5vw,2.65rem);line-height:1.02;letter-spacing:-.045em}.check-word{margin:16px 0 22px;color:var(--mint);font-size:clamp(2rem,8vw,4rem);font-weight:900;letter-spacing:-.06em}.answer-options{display:grid;grid-template-columns:1fr 1fr;gap:10px}.answer-option{min-height:58px;padding:12px;border:1px solid var(--line);border-radius:13px;background:#1c1830;color:var(--ink);font-weight:800;cursor:pointer}.answer-option:hover,.answer-option:focus-visible{border-color:var(--violet);background:#30274d}.answer-option.is-wrong{border-color:#ff8f9b;background:#4a1f34;color:#ffd9df}.check-feedback{min-height:1.5em;margin:14px 0;color:var(--warm);font-weight:700}.cancel-check{border:0;background:none;color:var(--muted);text-decoration:underline;text-underline-offset:4px;cursor:pointer}.project-note{max-width:700px;margin:34px auto 0}.project-note h2{margin-bottom:8px}.project-note p{margin:0;color:var(--muted);line-height:1.7}code{font-family:ui-monospace,monospace;color:var(--mint)}.visually-hidden{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}@media(max-width:620px){.study-header{align-items:start;flex-direction:column;margin-top:32px}.progress-card{align-self:stretch;display:flex;align-items:center;justify-content:space-between;text-align:left}.progress-card strong{margin:0}.study-actions{grid-template-columns:1fr 1fr}.action--reveal{grid-column:1/-1;grid-row:1}.flash-card{min-height:330px}}@media(prefers-reduced-motion:reduce){*,*::before,*::after{transition:none!important}}