/*! tailwindcss v4.2.2 | MIT License | https://tailwindcss.com */@layer properties{@supports (((-webkit-hyphens:none)) and (not (margin-trim:inline))) or ((-moz-orient:inline) and (not (color:rgb(from red r g b)))){*,:before,:after,::backdrop{--tw-rotate-x:initial;--tw-rotate-y:initial;--tw-rotate-z:initial;--tw-skew-x:initial;--tw-skew-y:initial;--tw-border-style:solid;--tw-blur:initial;--tw-brightness:initial;--tw-contrast:initial;--tw-grayscale:initial;--tw-hue-rotate:initial;--tw-invert:initial;--tw-opacity:initial;--tw-saturate:initial;--tw-sepia:initial;--tw-drop-shadow:initial;--tw-drop-shadow-color:initial;--tw-drop-shadow-alpha:100%;--tw-drop-shadow-size:initial}}}@layer theme{:root,:host{--font-sans:ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";--font-mono:"DM Mono", monospace;--color-white:#fff;--spacing:.5rem;--default-transition-duration:.15s;--default-transition-timing-function:cubic-bezier(.4, 0, .2, 1);--default-font-family:var(--font-sans);--default-mono-font-family:var(--font-mono);--color-primary:#1a1a1a;--color-accent:#e63946;--color-accent-dark:#b52830;--color-surface:#f5f0e8;--color-surface-dark:#ede7d8;--color-highlight:gold;--color-muted:#6b6b6b;--color-border:#d4cfc5;--color-success:#2d6a4f;--color-lang-en:#1d3557;--color-lang-vi:#c1121f;--color-lang-zh:#e63946;--font-display:"Space Grotesk", system-ui, sans-serif;--font-body:"Space Grotesk", system-ui, sans-serif;--shadow-card:4px 4px 0px 0px #1a1a1a;--shadow-card-accent:4px 4px 0px 0px #e63946;--shadow-button:3px 3px 0px 0px #1a1a1a;--ease-out-expo:cubic-bezier(.16, 1, .3, 1)}}@layer base{*,:after,:before,::backdrop{box-sizing:border-box;border:0 solid;margin:0;padding:0}::file-selector-button{box-sizing:border-box;border:0 solid;margin:0;padding:0}html,:host{-webkit-text-size-adjust:100%;-moz-tab-size:4;tab-size:4;line-height:1.5;font-family:var(--default-font-family,ui-sans-serif, system-ui, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji");font-feature-settings:var(--default-font-feature-settings,normal);font-variation-settings:var(--default-font-variation-settings,normal);-webkit-tap-highlight-color:transparent}hr{height:0;color:inherit;border-top-width:1px}abbr:where([title]){-webkit-text-decoration:underline dotted;text-decoration:underline dotted}h1,h2,h3,h4,h5,h6{font-size:inherit;font-weight:inherit}a{color:inherit;-webkit-text-decoration:inherit;text-decoration:inherit}b,strong{font-weight:bolder}code,kbd,samp,pre{font-family:var(--default-mono-font-family,ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace);font-feature-settings:var(--default-mono-font-feature-settings,normal);font-variation-settings:var(--default-mono-font-variation-settings,normal);font-size:1em}small{font-size:80%}sub,sup{vertical-align:baseline;font-size:75%;line-height:0;position:relative}sub{bottom:-.25em}sup{top:-.5em}table{text-indent:0;border-color:inherit;border-collapse:collapse}:-moz-focusring{outline:auto}progress{vertical-align:baseline}summary{display:list-item}ol,ul,menu{list-style:none}img,svg,video,canvas,audio,iframe,embed,object{vertical-align:middle;display:block}img,video{max-width:100%;height:auto}button,input,select,optgroup,textarea{font:inherit;font-feature-settings:inherit;font-variation-settings:inherit;letter-spacing:inherit;color:inherit;opacity:1;background-color:#0000;border-radius:0}::file-selector-button{font:inherit;font-feature-settings:inherit;font-variation-settings:inherit;letter-spacing:inherit;color:inherit;opacity:1;background-color:#0000;border-radius:0}:where(select:is([multiple],[size])) optgroup{font-weight:bolder}:where(select:is([multiple],[size])) optgroup option{padding-inline-start:20px}::file-selector-button{margin-inline-end:4px}::placeholder{opacity:1}@supports (not ((-webkit-appearance:-apple-pay-button))) or (contain-intrinsic-size:1px){::placeholder{color:currentColor}@supports (color:color-mix(in lab,red,red)){::placeholder{color:color-mix(in oklab,currentcolor 50%,transparent)}}}textarea{resize:vertical}::-webkit-search-decoration{-webkit-appearance:none}::-webkit-date-and-time-value{min-height:1lh;text-align:inherit}::-webkit-datetime-edit{display:inline-flex}::-webkit-datetime-edit-fields-wrapper{padding:0}::-webkit-datetime-edit{padding-block:0}::-webkit-datetime-edit-year-field{padding-block:0}::-webkit-datetime-edit-month-field{padding-block:0}::-webkit-datetime-edit-day-field{padding-block:0}::-webkit-datetime-edit-hour-field{padding-block:0}::-webkit-datetime-edit-minute-field{padding-block:0}::-webkit-datetime-edit-second-field{padding-block:0}::-webkit-datetime-edit-millisecond-field{padding-block:0}::-webkit-datetime-edit-meridiem-field{padding-block:0}::-webkit-calendar-picker-indicator{line-height:1}:-moz-ui-invalid{box-shadow:none}button,input:where([type=button],[type=reset],[type=submit]){-webkit-appearance:button;-moz-appearance:button;appearance:button}::file-selector-button{-webkit-appearance:button;-moz-appearance:button;appearance:button}::-webkit-inner-spin-button{height:auto}::-webkit-outer-spin-button{height:auto}[hidden]:where(:not([hidden=until-found])){display:none!important}}@layer components;@layer utilities{.absolute{position:absolute}.relative{position:relative}.start{inset-inline-start:var(--spacing)}.block{display:block}.flex{display:flex}.grid{display:grid}.hidden{display:none}.inline-block{display:inline-block}.transform{transform:var(--tw-rotate-x,) var(--tw-rotate-y,) var(--tw-rotate-z,) var(--tw-skew-x,) var(--tw-skew-y,)}.border{border-style:var(--tw-border-style);border-width:1px}.uppercase{text-transform:uppercase}.italic{font-style:italic}.filter{filter:var(--tw-blur,) var(--tw-brightness,) var(--tw-contrast,) var(--tw-grayscale,) var(--tw-hue-rotate,) var(--tw-invert,) var(--tw-saturate,) var(--tw-sepia,) var(--tw-drop-shadow,)}.transition{transition-property:color,background-color,border-color,outline-color,text-decoration-color,fill,stroke,--tw-gradient-from,--tw-gradient-via,--tw-gradient-to,opacity,box-shadow,transform,translate,scale,rotate,filter,-webkit-backdrop-filter,backdrop-filter,display,content-visibility,overlay,pointer-events;transition-timing-function:var(--tw-ease,var(--default-transition-timing-function));transition-duration:var(--tw-duration,var(--default-transition-duration))}}*,:before,:after{box-sizing:border-box;margin:0;padding:0}html{scroll-behavior:smooth;font-size:16px}body{font-family:var(--font-body);background-color:var(--color-surface);color:var(--color-primary);-webkit-font-smoothing:antialiased;min-height:100vh;line-height:1.6}h1,h2,h3,h4,h5,h6{font-family:var(--font-display);letter-spacing:-.02em;font-weight:700;line-height:1.1}.bh-grid{gap:2rem;display:grid}.bh-border-accent{border:2px solid var(--color-accent)}.bh-border-primary{border:2px solid var(--color-primary)}.bh-shadow{box-shadow:var(--shadow-card)}.bh-shadow-accent{box-shadow:var(--shadow-card-accent)}.bh-divider{background:var(--color-primary);width:100%;height:4px}.bh-divider-accent{background:var(--color-accent);width:100%;height:4px}.btn{font-family:var(--font-display);letter-spacing:.03em;text-transform:uppercase;cursor:pointer;white-space:nowrap;border:2px solid #0000;justify-content:center;align-items:center;gap:.5rem;padding:.75rem 1.5rem;font-size:.875rem;font-weight:600;text-decoration:none;transition:all .15s;display:inline-flex;position:relative}.btn-primary{background:var(--color-primary);color:var(--color-white);border-color:var(--color-primary);box-shadow:var(--shadow-button)}.btn-primary:hover{transform:translate(-2px,-2px);box-shadow:5px 5px #1a1a1a}.btn-primary:active{transform:translate(1px,1px);box-shadow:2px 2px #1a1a1a}.btn-accent{background:var(--color-accent);color:var(--color-white);border-color:var(--color-accent);box-shadow:3px 3px 0 0 var(--color-accent-dark)}.btn-accent:hover{box-shadow:5px 5px 0 0 var(--color-accent-dark);transform:translate(-2px,-2px)}.btn-accent:active{transform:translate(1px,1px)}.btn-outline{color:var(--color-primary);border-color:var(--color-primary);background:0 0}.btn-outline:hover{background:var(--color-primary);color:var(--color-white)}.btn-ghost{color:var(--color-muted);background:0 0;border-color:#0000}.btn-ghost:hover{background:var(--color-surface-dark);color:var(--color-primary)}.btn-sm{padding:.5rem 1rem;font-size:.75rem}.btn-lg{padding:1rem 2rem;font-size:1rem}.btn:disabled{opacity:.5;cursor:not-allowed;pointer-events:none}.input{width:100%;font-family:var(--font-body);border:2px solid var(--color-border);background:var(--color-white);color:var(--color-primary);outline:none;padding:.75rem 1rem;font-size:1rem;transition:border-color .15s}.input:focus{border-color:var(--color-primary)}.input::placeholder{color:var(--color-muted);font-style:italic}.input-error{border-color:var(--color-accent)}.form-label{text-transform:uppercase;letter-spacing:.08em;color:var(--color-primary);margin-bottom:.5rem;font-size:.75rem;font-weight:600;display:block}.form-group{flex-direction:column;gap:.25rem;margin-bottom:1.25rem;display:flex}.card{background:var(--color-white);border:2px solid var(--color-primary);box-shadow:var(--shadow-card);padding:1.5rem;transition:transform .15s,box-shadow .15s;position:relative}.card:hover{transform:translate(-2px,-2px);box-shadow:6px 6px #1a1a1a}.card-accent{border-color:var(--color-accent);box-shadow:var(--shadow-card-accent)}.flashcard-scene{perspective:1000px;cursor:pointer;width:100%;max-width:600px;height:360px;margin:0 auto}.flashcard-inner{width:100%;height:100%;transform-style:preserve-3d;transition:transform .5s var(--ease-out-expo);position:relative}.flashcard-inner.is-flipped{transform:rotateY(180deg)}.flashcard-face{backface-visibility:hidden;border:2px solid var(--color-primary);box-shadow:var(--shadow-card);flex-direction:column;justify-content:center;align-items:center;padding:2rem;display:flex;position:absolute;top:0;right:0;bottom:0;left:0}.flashcard-front{background:var(--color-white)}.flashcard-back{background:var(--color-primary);color:var(--color-surface);transform:rotateY(180deg)}.lang-badge{font-family:var(--font-mono);text-transform:uppercase;letter-spacing:.1em;border:1px solid;align-items:center;gap:.25rem;padding:.2rem .5rem;font-size:.7rem;font-weight:500;display:inline-flex}.lang-badge-en{color:var(--color-lang-en)}.lang-badge-vi{color:var(--color-lang-vi)}.lang-badge-zh{color:var(--color-lang-zh)}.plan-badge{font-family:var(--font-mono);text-transform:uppercase;letter-spacing:.12em;border:1px solid;align-items:center;padding:.15rem .5rem;font-size:.65rem;font-weight:500;display:inline-flex}.plan-free{color:var(--color-muted);border-color:var(--color-muted)}.plan-pro{color:var(--color-highlight);border-color:var(--color-highlight);background:var(--color-primary)}.navbar{z-index:100;background:var(--color-primary);color:var(--color-surface);border-bottom:4px solid var(--color-accent);justify-content:space-between;align-items:center;height:64px;padding:0 2rem;display:flex;position:sticky;top:0}.navbar-brand{font-family:var(--font-display);letter-spacing:-.02em;color:var(--color-surface);align-items:center;gap:.5rem;font-size:1.25rem;font-weight:700;text-decoration:none;display:flex}.navbar-brand span.accent{color:var(--color-accent)}.navbar-nav{align-items:center;gap:1.5rem;display:flex}.nav-link{font-family:var(--font-mono);text-transform:uppercase;letter-spacing:.08em;color:var(--color-surface);opacity:.7;font-size:.75rem;text-decoration:none;transition:opacity .15s}.nav-link:hover,.nav-link.active{opacity:1;color:var(--color-highlight)}.page-container{max-width:1200px;margin:0 auto;padding:3rem 2rem}.page-header{border-bottom:2px solid var(--color-primary);justify-content:space-between;align-items:flex-end;gap:1rem;margin-bottom:3rem;padding-bottom:1.5rem;display:flex}.page-title{letter-spacing:-.03em;font-size:clamp(2rem,5vw,3rem);font-weight:700}.spinner{border:3px solid var(--color-border);border-top-color:var(--color-primary);border-radius:50%;width:24px;height:24px;animation:.7s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.loading-screen{background:var(--color-surface);z-index:9999;justify-content:center;align-items:center;display:flex;position:fixed;top:0;right:0;bottom:0;left:0}.modal-overlay{z-index:200;background:#1a1a1ab3;justify-content:center;align-items:center;padding:2rem;animation:.15s fadeIn;display:flex;position:fixed;top:0;right:0;bottom:0;left:0}.modal{background:var(--color-surface);border:2px solid var(--color-primary);width:100%;max-width:560px;max-height:90vh;animation:slideUp .2s var(--ease-out-expo);overflow-y:auto;box-shadow:8px 8px #1a1a1a4d}.modal-header{border-bottom:2px solid var(--color-primary);justify-content:space-between;align-items:center;padding:1.5rem;display:flex}.modal-body{padding:1.5rem}.modal-footer{border-top:2px solid var(--color-border);justify-content:flex-end;gap:.75rem;padding:1rem 1.5rem;display:flex}@keyframes fadeIn{0%{opacity:0}to{opacity:1}}@keyframes slideUp{0%{opacity:0;transform:translateY(16px)}to{opacity:1;transform:translateY(0)}}@keyframes slideIn{0%{opacity:0;transform:translate(-16px)}to{opacity:1;transform:translate(0)}}.animate-fade-in{animation:.3s forwards fadeIn}.animate-slide-in{animation:slideIn .3s var(--ease-out-expo) forwards}::-webkit-scrollbar{width:6px}::-webkit-scrollbar-track{background:var(--color-surface-dark)}::-webkit-scrollbar-thumb{background:var(--color-primary)}::-webkit-scrollbar-thumb:hover{background:var(--color-accent)}@media(max-width:768px){.page-container{padding:2rem 1rem}.navbar{padding:0 1rem}.page-header{flex-direction:column;align-items:flex-start}}@property --tw-rotate-x{syntax:"*";inherits:false}@property --tw-rotate-y{syntax:"*";inherits:false}@property --tw-rotate-z{syntax:"*";inherits:false}@property --tw-skew-x{syntax:"*";inherits:false}@property --tw-skew-y{syntax:"*";inherits:false}@property --tw-border-style{syntax:"*";inherits:false;initial-value:solid}@property --tw-blur{syntax:"*";inherits:false}@property --tw-brightness{syntax:"*";inherits:false}@property --tw-contrast{syntax:"*";inherits:false}@property --tw-grayscale{syntax:"*";inherits:false}@property --tw-hue-rotate{syntax:"*";inherits:false}@property --tw-invert{syntax:"*";inherits:false}@property --tw-opacity{syntax:"*";inherits:false}@property --tw-saturate{syntax:"*";inherits:false}@property --tw-sepia{syntax:"*";inherits:false}@property --tw-drop-shadow{syntax:"*";inherits:false}@property --tw-drop-shadow-color{syntax:"*";inherits:false}@property --tw-drop-shadow-alpha{syntax:"<percentage>";inherits:false;initial-value:100%}@property --tw-drop-shadow-size{syntax:"*";inherits:false}