/* Mobile first: the board gets the viewport minus two 8px gutters. */
main { width: calc(100% - 16px); max-width: 1120px; margin: 12px auto 0; padding-bottom: calc(92px + env(safe-area-inset-bottom,0px)); }
.site-header { display: flex; align-items: center; justify-content: space-between; gap: 8px; min-height: 48px; }
.site-header .brand { color: var(--text); text-decoration: none; font-size: 22px; font-weight: 800; white-space: nowrap; min-height: 44px; display: flex; align-items: center; }
.brand span { display: none; font-size: 12px; font-weight: 500; color: var(--muted); margin-left: 12px; }
.site-header .text-button { margin: 0; font-size: 13px; padding-inline: 8px; }
.study-nav { position: fixed; z-index: 30; left: 0; right: 0; bottom: 0; display: grid; grid-template-columns: repeat(5,minmax(0,1fr)); gap: 2px; margin: 0; padding: 6px max(4px,env(safe-area-inset-right,0px)) calc(6px + env(safe-area-inset-bottom,0px)) max(4px,env(safe-area-inset-left,0px)); border-top: 1px solid var(--line); background: var(--surface); box-shadow: 0 -4px 20px #00000018; }
.study-nav button { display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 5px; width: 100%; min-width: 0; min-height: 56px; margin: 0; padding: 6px 2px; border-radius: 8px; color: var(--muted); background: transparent; text-align: center; font-size: 11px; font-weight: 650; line-height: 1.2; box-shadow: none; transform: none; }
.study-nav button span { float: none; }
.study-nav button svg { width: 23px; height: 23px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.study-nav button[aria-current="page"] { color: var(--accent); background: color-mix(in srgb,var(--accent) 10%,transparent); }
#identity-notice { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 10px; margin-top: 12px; font-size: 12px; line-height: 1.6; color: var(--muted); }
#identity-notice .text-button { width: auto; margin: 0; min-height: 44px; padding: 8px; }
.identity-toggle { display: flex; align-items: center; gap: 12px; min-height: 48px; margin: 12px 0; cursor: pointer; }
.identity-toggle input[type="checkbox"] { width: 24px; height: 24px; min-height: 24px; margin: 0; flex: 0 0 auto; }
.theme-setting .identity-toggle { margin-bottom: 0; }
#study-notice { font-size: 14px; line-height: 1.6; color: var(--warning); background: var(--surface); border-radius: 8px; padding: 12px; }
#study-notice:empty { display: none; }
#study-app { margin-top: 24px; }
#diagnosis-view { max-width: 800px; margin: 0 auto; }
.study-eyebrow { text-transform: uppercase; letter-spacing: 1.2px; font-size: 11px; font-weight: 750; color: var(--accent); margin: 0 0 10px; }
.study-heading { font-size: 24px; line-height: 1.25; font-weight: 800; letter-spacing: -.5px; margin: 0 0 12px; }
.study-intro { font-size: 15px; line-height: 1.7; color: var(--muted); max-width: 710px; margin: 0 0 22px; }
.study-card { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.study-card h2 { font-size: 22px; font-weight: 750; margin: 0 0 14px; }
.study-card h3 { margin: 0 0 12px; font-size: 20px; }
.study-card p { line-height: 1.7; }
.study-card button { margin-top: 16px; }
.study-grid { display: grid; grid-template-columns: minmax(0,1fr); gap: 18px; align-items: start; }
.study-stack { display: grid; gap: 16px; }
.study-stats { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; margin: 16px 0; }
.study-stat { border-top: 1px solid var(--line); padding: 14px 0; }
.study-stat strong { display: block; font-size: 26px; font-weight: 750; color: var(--accent); }
.study-stat small { color: var(--muted); font-size: 12px; }
.study-actions { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; margin-top: 20px; }
.study-actions button, .study-actions a { margin: 0; width: auto; flex: 1; text-align: center; min-width: 120px; min-height: 48px; }
.study-small { font-size: 13px; color: var(--muted); line-height: 1.65; }
.study-tag { display: inline-block; font-size: 12px; line-height: 1.4; color: var(--muted); background: var(--surface-raised); padding: 5px 8px; border-radius: 5px; }
.study-tag.done { color: var(--accent-text); background: var(--accent); }
.study-tag.due { color: var(--warning); background: var(--surface-raised); }
.daily-steps { padding: 0; list-style: none; margin: 22px 0; }
.daily-steps li { display: flex; gap: 12px; align-items: flex-start; padding: 16px 0; border-bottom: 1px solid var(--line); }
.daily-steps li:last-child { border-bottom: 0; }
.daily-steps .step-number { display: grid; place-items: center; border: 1px solid var(--line); background: var(--surface-raised); color: var(--accent); width: 32px; height: 32px; flex-shrink: 0; border-radius: 50%; font-size: 14px; font-weight: 750; }
.daily-steps strong { display: block; font-size: 15px; margin: 1px 0 5px; }
.daily-steps p { font-size: 14px; color: var(--muted); line-height: 1.5; margin: 0; }
.study-course { display: grid; gap: 24px; }
.course-section h2 { font-size: 22px; font-weight: 750; margin: 0 0 12px; }
.course-lessons { display: grid; grid-template-columns: minmax(0,1fr); gap: 12px; }
.lesson-card { display: block; text-align: left; background: var(--surface); color: var(--text); border: 1px solid var(--line); border-radius: 12px; padding: 18px; margin: 0; font-weight: 400; box-shadow: none; }
.lesson-card strong { display: block; font-size: 16px; font-weight: 750; margin: 10px 0 8px; }
.lesson-card p { margin: 0; font-size: 14px; line-height: 1.6; color: var(--muted); }
.lesson-card span { float: none; }
.lesson-card:disabled { cursor: not-allowed; }
.lesson-content { max-width: 780px; margin: 0 auto; }
.lesson-content p, .lesson-content li { line-height: 1.8; font-size: 16px; }
.lesson-content h3 { margin-top: 24px; }
.lesson-content ul { padding-left: 23px; }
.lesson-takeaway { border-left: 3px solid var(--accent); background: var(--surface-raised); padding: 16px; margin: 23px 0; line-height: 1.7; }
.quiz-options { display: grid; gap: 10px; }
.quiz-options button { margin: 0; text-align: left; background: var(--surface-raised); color: var(--text); border: 1px solid var(--line); font-weight: 500; padding: 15px; box-shadow: none; }
.quiz-options button.quiz-correct { border-color: var(--accent); box-shadow: inset 4px 0 var(--accent); }
.quiz-options button.quiz-wrong { border-color: var(--error); box-shadow: inset 4px 0 var(--error); }
.quiz-feedback { min-height: 25px; color: var(--accent); font-size: 15px; line-height: 1.7; }
/* Hints never become a right-hand column, including on desktop. */
.study-board-layout { display: grid; grid-template-columns: minmax(0,1fr); gap: 14px; align-items: start; width: 100%; max-width: 480px; min-width: 0; margin-inline: auto; overflow: visible; }
.study-board-wrap { max-width: 480px; width: 100%; min-width: 0; margin-inline: auto; overflow: visible; }
.study-board-layout > .study-card { border: 0; padding: 0; background: transparent; }
.study-board-head { display: flex; justify-content: space-between; align-items: center; font-size: 13px; color: var(--muted); margin: 0 0 12px; gap: 12px; }
.study-move-form { display: flex; flex-wrap: wrap; gap: 8px; align-items: end; background: none; padding: 0; margin: 16px 0 0; border: 0; box-shadow: none; border-radius: 0; }
.study-move-form label { flex: 1; min-width: 140px; font-size: 14px; }
.study-move-form button { width: auto; margin: 0; padding: 12px; }
.study-promotion { margin-top: 12px; max-width: 210px; font-size: 14px; }
.study-feedback { background: var(--surface); border-radius: 8px; padding: 12px; line-height: 1.6; margin: 12px 0; min-height: 48px; font-size: 15px; }
.study-feedback.warning { color: var(--warning); border-left: 3px solid var(--warning); }
.study-feedback.error { color: var(--error); }
.study-explanation { border-top: 1px solid var(--line); padding-top: 18px; line-height: 1.8; font-size: 15px; }
.study-explanation h3 { font-size: 20px; }
.study-explanation p { margin: 0 0 12px; }
.study-replay { display: flex; gap: 8px; margin-top: 15px; }
.study-replay button { margin: 0; text-align: center; padding: 10px 6px; flex: 1; font-size: 13px; }
.study-line { font-family: ui-monospace,monospace; font-size: 14px; line-height: 1.8; overflow-wrap: anywhere; }
.study-filter { display: grid; grid-template-columns: minmax(0,1fr); gap: 12px; margin: 20px 0; }
.study-review-list { display: grid; gap: 12px; }
.study-review-card { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 16px; display: flex; flex-direction: column; gap: 16px; justify-content: space-between; align-items: stretch; }
.study-review-card h3 { font-size: 18px; margin: 0 0 7px; }
.study-review-card p { font-size: 14px; line-height: 1.6; color: var(--muted); margin: 0; }
.study-review-card button { margin: 0; width: auto; padding: 12px 16px; }
.study-profile-form { margin: 20px 0; padding: 16px; }
.study-profile-row { display: grid; grid-template-columns: minmax(0,1fr); gap: 12px; align-items: end; }
.study-profile-row button { margin: 0; width: auto; padding: 12px 16px; }
.study-progress-list { display: grid; gap: 12px; }
.study-progress-list > div { display: flex; justify-content: space-between; align-items: center; gap: 16px; border-bottom: 1px solid var(--line); padding: 12px 0; font-size: 14px; }
.study-progress-list progress { accent-color: var(--accent); width: 100px; max-width: 35%; flex-shrink: 0; }
.study-file { background: var(--surface-raised); border: 1px solid var(--line); border-radius: 8px; color: var(--text); padding: 14px; cursor: pointer; font-weight: 650; font-size: 14px; min-height: 48px; }
.study-file input { font-size: 13px; background: var(--bg); margin-top: 5px; }
.study-empty { padding: 28px 16px; border: 1px dashed var(--line); border-radius: 12px; text-align: center; background: var(--surface); line-height: 1.8; }
.study-profile-label { color: var(--muted); font-size: 13px; margin: 0 0 20px; }
.study-session-banner { display: flex; justify-content: space-between; align-items: center; gap: 12px; background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 8px 12px; margin-bottom: 20px; font-size: 13px; }
.study-session-banner button { margin: 0; padding: 8px 0; min-width: 60px; width: auto; background: none; color: var(--accent); box-shadow: none; text-decoration: underline; font-size: 13px; }
.study-complete { max-width: 700px; margin: 0 auto; text-align: center; padding: 28px 18px; }
.study-complete .completion-icon { display: grid; place-items: center; font-size: 32px; width: 70px; height: 70px; background: var(--surface-raised); color: var(--accent); border-radius: 50%; margin: 0 auto 20px; }
.study-card a { color: var(--accent); display: inline-flex; align-items: center; min-height: 44px; }
.study-time-setting { max-width: 220px; margin-top: 20px; }
#study-app button:disabled { cursor: default; }
footer { max-width: 840px; border-top: 1px solid var(--line); padding-top: 22px; margin-top: 36px; }
.study-list-compact { padding-left: 18px; line-height: 1.9; font-size: 14px; color: var(--muted); }
.study-loading { padding: 35px 16px; text-align: center; color: var(--muted); }
.study-back { display: inline-block; width: auto; padding: 10px 6px; background: none; color: var(--accent); box-shadow: none; font-size: 14px; margin: 0 0 16px; }
.study-view-title { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between; }
.study-view-title button { width: auto; margin: 0; padding: 10px 12px; font-size: 14px; }
.study-link-button { width: auto; background: none; color: var(--accent); box-shadow: none; text-decoration: underline; font-size: 14px; margin: 6px 0; padding: 10px 4px; }
.study-version { font-size: 12px; color: var(--muted); margin-top: 20px; }
@media (max-width: 599px) {
  /* The diagnostic board lives inside the form: cancel its card inset. */
  #puzzle-stage { width: calc(100% + 34px); max-width: 480px; margin-left: -17px; }
  #puzzle-stage > :not(.chessboard) { margin-left: 12px; margin-right: 12px; }
  #puzzle-stage > progress { width: calc(100% - 24px); }
  #puzzle-stage > button { width: calc(100% - 24px); }
}
@media (min-width: 600px) {
  .course-lessons { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .study-filter { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .study-card { padding: 22px; }
  .study-profile-row { grid-template-columns: 1fr 1.5fr; }
  .study-profile-row button { grid-column: 1 / -1; }
  .study-review-card { flex-direction: row; align-items: center; }
  .study-review-card button { flex-shrink: 0; }
  .lesson-content .study-card { padding: 26px; }
}
@media (min-width: 900px) {
  main { width: calc(100% - 268px); margin: 24px 24px 0 244px; padding-bottom: 16px; max-width: 1240px; }
  .site-header { min-height: 52px; }
  .brand span { display: inline; }
  .study-nav { top: 0; bottom: 0; left: 0; right: auto; width: 220px; display: flex; flex-direction: column; gap: 8px; padding: 88px 12px 24px; border: 0; border-right: 1px solid var(--line); box-shadow: none; }
  .study-nav::before { content: "СВОЙ ХОД"; position: absolute; top: 34px; left: 26px; color: var(--text); letter-spacing: 1.6px; font-size: 14px; font-weight: 800; }
  .study-nav button { flex-direction: row; justify-content: flex-start; gap: 14px; min-height: 52px; padding: 12px 16px; font-size: 15px; }
  .study-nav button svg { width: 24px; height: 24px; flex-shrink: 0; }
  #study-app { margin-top: 30px; }
  .study-grid { grid-template-columns: minmax(0,1.65fr) minmax(220px,1fr); gap: 22px; }
  .study-profile-row { grid-template-columns: 1fr 1.5fr auto; }
  .study-profile-row button { grid-column: auto; }
}
@media (hover: hover) {
  .study-nav button:hover:not(:disabled) { color: var(--text); background: var(--surface-raised); }
  .lesson-card:hover:not(:disabled) { border-color: var(--accent); background: var(--surface-raised); }
  .quiz-options button:hover:not(:disabled) { background: var(--surface-raised); border-color: var(--accent); }
  .study-back:hover:not(:disabled), .study-link-button:hover:not(:disabled) { background: var(--surface); }
}
.assessment-screen { max-width: 100%; }
.assessment-screen > progress { width: 100%; max-width: 480px; height: 8px; accent-color: var(--accent); }
.skill-map { margin-block: 24px; }
.skill-row { background: var(--surface); border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; margin-top: 8px; }
.skill-row summary { display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 8px; font-size: 15px; }
.skill-row summary > progress, .skill-row summary > .study-small { grid-column: 1 / -1; width: 100%; }
.skill-row progress { height: 8px; accent-color: var(--accent); }
.skill-caption { color: var(--muted); font-size: 13px; }
.matrix-card { padding: 12px 8px; margin-top: 20px; }
.error-matrix { display: grid; grid-template-columns: 48px repeat(5,minmax(0,1fr)); gap: 3px; max-width: 480px; }
.matrix-label { font-size: 10px; display: grid; align-items: center; overflow-wrap: anywhere; padding: 3px 0; }
.error-matrix .matrix-cell { min-height: 48px; min-width: 0; margin: 0; padding: 4px; border-radius: 6px; box-shadow: none; font-size: 14px; color: var(--text); background: color-mix(in srgb, var(--error) calc(var(--heat) * 65%), var(--surface-raised)); }
.matrix-moments > article { margin-top: 8px; display: block; }
.diagnostic-job { margin-block: 16px; padding: 12px; background: var(--surface); border: 1px solid var(--line); border-radius: 8px; }
.diagnostic-job progress { width: 100%; height: 8px; accent-color: var(--accent); }
.study-notification { padding: 8px; color: var(--accent); }
.block-score { font-size: 48px; font-weight: 800; margin: 12px 0; }
.error-review { max-width: 560px; margin: 0 auto; }
.error-review-top { display: flex; align-items: center; gap: 12px; margin-bottom: 12px; }
.error-review-top h2 { font-size: 20px; margin: 0; }
.error-review-top button { margin: 0; padding: 8px; min-width: 72px; }
.error-review-explanation { line-height: 1.6; }
.error-review-source,.error-review-legend { color: var(--muted); font-size: 13px; }
.error-review-actions button { flex: 1 1 130px; margin: 0; min-height: 48px; }
.task-pref { display: flex; gap: 12px; align-items: center; margin: 12px 0; }
.task-pref input { width: 20px; height: 20px; margin: 0; accent-color: var(--accent); }
.study-duration-options { display:flex; gap:8px; }
.study-duration-options button { flex:1; }
.study-duration-options button[aria-pressed="true"] { background:#739552; color:#fff; }
.games-feed { background:var(--surface); border-radius:12px; padding:12px; }
.game-row { display:grid; grid-template-columns:30px minmax(0,1fr) auto; gap:9px; align-items:center; padding:12px 0; border-bottom:1px solid var(--line); }
.game-copy { min-width:0; } .game-copy strong,.game-copy small {display:block;overflow-wrap:anywhere;}
.game-copy strong {font-size:14px;} .game-copy small {font-size:12px;color:var(--muted);margin-top:3px;}
.game-result {width:30px;height:30px;display:grid;place-items:center;border-radius:8px;font-weight:800;}
.game-result.win{background:#3f5f2a;color:#cfe9b3}.game-result.loss{background:#5f2a2a;color:#f2b8b8}.game-result.draw{background:#4a4a4a;color:#eee}
.game-action{padding:6px 0;background:none;color:#81b64c;font-size:12px;box-shadow:none;white-space:nowrap;}
.games-updated{font-size:11px;color:var(--muted);}.games-error{color:#e36969}.games-refresh{font-size:13px;}