/* ============================================================================
   NPPE PREP — "THE INSTRUMENT" DESIGN SYSTEM
   A precision-instrument visual language for professional-practice exam prep.
   Palette: Graphite & Signal · Type: Space Grotesk / IBM Plex Sans / IBM Plex Mono
   ========================================================================== */

:root {
    /* ---- Color: Graphite & Signal ---- */
    --paper:        #EBEDF0;   /* cool technical vellum — light surfaces      */
    --paper-2:      #E3E6EA;   /* recessed paper                              */
    --card:         #F6F7F9;   /* raised card on paper                        */
    --ink:          #17191F;   /* graphite near-black — text & dark panels    */
    --ink-2:        #20232B;   /* dark panel elevation                        */
    --slate:        #4A515E;   /* secondary text                             */
    --slate-2:      #7A828F;   /* tertiary / meta text                        */
    --line:         #C9CCD1;   /* hairlines / grid on light                   */
    --line-dark:    #2E323C;   /* hairlines / grid on dark                    */

    --signal:       #F0522A;   /* the single accent — survey/signal orange    */
    --signal-ink:   #D23F1B;   /* accent pressed                              */
    --signal-wash:  rgba(240, 82, 42, 0.08);

    --pass:         #2E7D5B;   /* exam-correct only (functional)              */
    --pass-wash:    rgba(46, 125, 91, 0.10);
    --fail:         #B23A2E;   /* exam-incorrect only (functional)            */
    --fail-wash:    rgba(178, 58, 46, 0.10);

    /* ---- Type ---- */
    --font-display: "Space Grotesk", system-ui, sans-serif;
    --font-body:    "IBM Plex Sans", system-ui, sans-serif;
    --font-mono:    "IBM Plex Mono", ui-monospace, monospace;

    /* ---- Metrics ---- */
    --radius:   3px;
    --gap:      clamp(1rem, 2vw, 1.5rem);
    --ease:     cubic-bezier(0.2, 0.7, 0.2, 1);
    --ease-mech: cubic-bezier(0.85, 0, 0.15, 1);   /* mechanical / plotter    */
    --shadow:   0 1px 0 var(--line), 0 18px 40px -24px rgba(23, 25, 31, 0.35);
}

/* ---- Reset ---- */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; }
html { -webkit-text-size-adjust: 100%; }
body {
    font-family: var(--font-body);
    background: var(--paper);
    color: var(--ink);
    line-height: 1.55;
    -webkit-font-smoothing: antialiased;
    text-rendering: optimizeLegibility;
    min-height: 100vh;
}
img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; cursor: pointer; background: none; border: none; }
input, textarea, select { font: inherit; color: inherit; }
::selection { background: var(--signal); color: #fff; }

/* ---- Technical grid background (graph paper) ---- */
.grid-bg {
    background-image:
        linear-gradient(var(--line) 1px, transparent 1px),
        linear-gradient(90deg, var(--line) 1px, transparent 1px);
    background-size: 28px 28px;
    background-position: -1px -1px;
    opacity: 1;
}
.grid-bg--faint {
    background-image:
        linear-gradient(rgba(201,204,209,0.45) 1px, transparent 1px),
        linear-gradient(90deg, rgba(201,204,209,0.45) 1px, transparent 1px);
    background-size: 28px 28px;
}
.grid-bg--dark {
    background-image:
        linear-gradient(var(--line-dark) 1px, transparent 1px),
        linear-gradient(90deg, var(--line-dark) 1px, transparent 1px);
    background-size: 32px 32px;
}

/* ============================================================================
   TYPOGRAPHY
   ========================================================================== */
.eyebrow {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.22em;
    text-transform: uppercase;
    color: var(--slate-2);
    display: inline-flex;
    align-items: center;
    gap: 0.6em;
}
.eyebrow--signal { color: var(--signal); }
.eyebrow::before {
    content: "";
    width: 1.6em; height: 1px;
    background: currentColor;
    opacity: 0.6;
}
.eyebrow.no-rule::before { display: none; }

.display {
    font-family: var(--font-display);
    font-weight: 600;
    letter-spacing: -0.02em;
    line-height: 1.02;
    color: var(--ink);
}
.display-xl { font-size: clamp(2.6rem, 6vw, 4.6rem); }
.display-lg { font-size: clamp(2rem, 4.5vw, 3.2rem); }
.display-md { font-size: clamp(1.5rem, 3vw, 2.1rem); }

h1, h2, h3 { font-family: var(--font-display); font-weight: 600; letter-spacing: -0.015em; line-height: 1.1; }

.lead { font-size: 1.075rem; color: var(--slate); max-width: 46ch; }
.muted { color: var(--slate-2); }

.mono { font-family: var(--font-mono); }
.anno {
    font-family: var(--font-mono);
    font-size: 0.74rem;
    letter-spacing: 0.04em;
    color: var(--slate-2);
}
.anno strong { color: var(--ink); font-weight: 500; }

/* ============================================================================
   FRAME — corner registration brackets (the signature)
   ========================================================================== */
.frame { position: relative; }
.frame::before, .frame::after {
    content: "";
    position: absolute;
    width: 15px; height: 15px;
    border: 1.5px solid var(--signal);
    pointer-events: none;
    z-index: 2;
}
.frame::before { top: -1px;    left: -1px;  border-right: 0; border-bottom: 0; }
.frame::after  { bottom: -1px; right: -1px; border-left: 0;  border-top: 0;   }
.frame--ink::before, .frame--ink::after { border-color: var(--ink); }

/* Full four-corner registration marks (decorative wrapper) */
.reg { position: relative; }
.reg > .reg-mark {
    position: absolute; width: 14px; height: 14px; z-index: 3; pointer-events: none;
    border: 1.5px solid var(--signal);
}
.reg-mark.tl { top: 10px;    left: 10px;    border-right: 0; border-bottom: 0; }
.reg-mark.tr { top: 10px;    right: 10px;   border-left: 0;  border-bottom: 0; }
.reg-mark.bl { bottom: 10px; left: 10px;    border-right: 0; border-top: 0;    }
.reg-mark.br { bottom: 10px; right: 10px;   border-left: 0;  border-top: 0;    }

/* ============================================================================
   BUTTONS
   ========================================================================== */
.btn {
    --btn-fg: var(--ink);
    display: inline-flex; align-items: center; justify-content: center; gap: 0.7em;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--btn-fg);
    padding: 0.95rem 1.4rem;
    border: 1.5px solid var(--ink);
    border-radius: var(--radius);
    background: transparent;
    position: relative;
    transition: background 0.25s var(--ease), color 0.25s var(--ease),
                border-color 0.25s var(--ease), transform 0.15s var(--ease);
    will-change: transform;
}
.btn .arrow { transition: transform 0.28s var(--ease-mech); }
.btn:hover .arrow { transform: translateX(4px); }
.btn:active { transform: translateY(1px); }
.btn:focus-visible { outline: 2px solid var(--signal); outline-offset: 3px; }

.btn--primary {
    background: var(--signal);
    border-color: var(--signal);
    color: #fff;
}
.btn--primary:hover { background: var(--signal-ink); border-color: var(--signal-ink); }

.btn--dark {
    background: var(--ink);
    border-color: var(--ink);
    color: var(--paper);
}
.btn--dark:hover { background: #000; }

.btn--ghost { border-color: var(--line); color: var(--slate); }
.btn--ghost:hover { border-color: var(--ink); color: var(--ink); background: rgba(23,25,31,0.03); }

.btn--danger { border-color: var(--fail); color: var(--fail); }
.btn--danger:hover { background: var(--fail); color: #fff; }

.btn--block { display: flex; width: 100%; }
.btn--lg { padding: 1.1rem 1.6rem; font-size: 0.86rem; }

/* ============================================================================
   FIELDS
   ========================================================================== */
.field { display: block; margin-bottom: 1.15rem; }
.field__label {
    display: flex; align-items: center; justify-content: space-between;
    font-family: var(--font-mono);
    font-size: 0.72rem; font-weight: 500; letter-spacing: 0.12em; text-transform: uppercase;
    color: var(--slate); margin-bottom: 0.5rem;
}
.field__label .idx { color: var(--signal); }
.field__wrap { position: relative; }
.field__input {
    width: 100%;
    padding: 0.85rem 0.95rem;
    background: var(--card);
    border: 1.5px solid var(--line);
    border-radius: var(--radius);
    color: var(--ink);
    transition: border-color 0.2s var(--ease), box-shadow 0.2s var(--ease), background 0.2s var(--ease);
}
.field__input::placeholder { color: var(--slate-2); }
.field__input:focus {
    outline: none;
    border-color: var(--ink);
    background: #fff;
    box-shadow: inset 0 0 0 1px var(--ink);
}
/* focus registration tick */
.field__wrap::after {
    content: "";
    position: absolute; top: -1px; right: -1px;
    width: 12px; height: 12px;
    border-top: 1.5px solid var(--signal);
    border-right: 1.5px solid var(--signal);
    opacity: 0; transform: translate(-3px, 3px);
    transition: opacity 0.2s var(--ease), transform 0.2s var(--ease);
    pointer-events: none;
}
.field__wrap:focus-within::after { opacity: 1; transform: translate(0, 0); }

textarea.field__input { resize: vertical; min-height: 6.5rem; line-height: 1.5; }

/* checkbox — technical square */
.check { display: inline-flex; align-items: center; gap: 0.6rem; cursor: pointer; user-select: none;
    font-size: 0.9rem; color: var(--slate); }
.check input { position: absolute; opacity: 0; width: 0; height: 0; }
.check .box {
    width: 18px; height: 18px; border: 1.5px solid var(--line); border-radius: 2px;
    background: var(--card); display: grid; place-items: center;
    transition: border-color 0.15s var(--ease), background 0.15s var(--ease);
}
.check .box::after { content: ""; width: 9px; height: 9px; background: var(--signal); transform: scale(0);
    transition: transform 0.15s var(--ease-mech); }
.check input:checked + .box { border-color: var(--signal); }
.check input:checked + .box::after { transform: scale(1); }
.check input:focus-visible + .box { outline: 2px solid var(--signal); outline-offset: 2px; }

/* ============================================================================
   PANELS / CARDS / DIVIDERS
   ========================================================================== */
.panel { background: var(--card); border: 1.5px solid var(--line); border-radius: var(--radius); }
.panel--dark { background: var(--ink); color: var(--paper); border-color: var(--line-dark); }

.divider { display: flex; align-items: center; gap: 1rem; color: var(--slate-2);
    font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.2em; text-transform: uppercase; }
.divider::before, .divider::after { content: ""; height: 1px; background: var(--line); flex: 1; }

.tag {
    font-family: var(--font-mono); font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase;
    padding: 0.28rem 0.55rem; border: 1px solid currentColor; border-radius: 2px; display: inline-block;
}
.tag--pass { color: var(--pass); background: var(--pass-wash); border-color: transparent; }
.tag--fail { color: var(--fail); background: var(--fail-wash); border-color: transparent; }
.tag--signal { color: var(--signal); background: var(--signal-wash); border-color: transparent; }

/* Google / provider button glyph */
.provider { display: inline-flex; align-items: center; justify-content: center; gap: 0.7rem; }

/* ============================================================================
   MOTION
   ========================================================================== */
@keyframes fadeUp   { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }
@keyframes drawX    { from { transform: scaleX(0); } to { transform: scaleX(1); } }
@keyframes drawY    { from { transform: scaleY(0); } to { transform: scaleY(1); } }
@keyframes bracketIn{ from { opacity: 0; transform: translate(6px, 6px); } to { opacity: 1; transform: none; } }
@keyframes ringDraw { from { stroke-dashoffset: var(--dash, 760); } to { stroke-dashoffset: 0; } }
@keyframes blink    { 0%,100% { opacity: 1; } 50% { opacity: 0.15; } }

/* page-load sequence: parent .seq, children stagger via --i */
.seq > * { opacity: 0; animation: fadeUp 0.7s var(--ease) forwards; animation-delay: calc(var(--i, 0) * 90ms + 120ms); }

/* scroll reveal (JS adds .is-in) */
[data-reveal] { opacity: 0; transform: translateY(22px); transition: opacity 0.7s var(--ease), transform 0.7s var(--ease); }
[data-reveal].is-in { opacity: 1; transform: none; }
[data-reveal][data-reveal="x"] { transform: translateX(-22px); }
[data-reveal].is-in { transform: none; }

.live-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--signal); display: inline-block;
    animation: blink 1.8s steps(1) infinite; }

/* ---- Ambient study-motif field (auth screens) ----
   Thin technical line-icons (books, exam sheets, notes, drafting tools)
   drifting slowly behind a form. Kept faint so it never competes with content. */
.study-bg { position: absolute; inset: 0; overflow: hidden; pointer-events: none; z-index: 0; }
.study-bg .motif {
    position: absolute;
    color: var(--slate-2);
    opacity: var(--op, 0.16);
    animation: floatDrift var(--dur, 28s) ease-in-out var(--delay, 0s) infinite;
    will-change: transform;
}
.study-bg .motif--signal { color: var(--signal); opacity: var(--op, 0.14); }
.study-bg .motif svg { width: 100%; height: 100%; display: block; }
@keyframes floatDrift {
    0%   { transform: translate(0, 0) rotate(var(--rot, 0deg)); }
    50%  { transform: translate(var(--dx, 10px), var(--dy, -16px)) rotate(calc(var(--rot, 0deg) + var(--spin, 3deg))); }
    100% { transform: translate(0, 0) rotate(var(--rot, 0deg)); }
}

/* ---- utilities ---- */
.container { width: min(100% - 2.5rem, 1160px); margin-inline: auto; }
.stack { display: flex; flex-direction: column; }
.center { display: grid; place-items: center; }
.hairline { height: 1px; background: var(--line); border: 0; }
.vh { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { animation-duration: 0.001ms !important; animation-delay: 0ms !important;
        transition-duration: 0.001ms !important; }
    .seq > *, [data-reveal] { opacity: 1 !important; transform: none !important; }
}

/* ---- ASP.NET validation styling ---- */
.validation-summary-valid { display: none; }
.validation-summary-errors {
    border: 1px solid var(--fail);
    border-left: 3px solid var(--fail);
    background: var(--fail-wash);
    border-radius: var(--radius);
    padding: 0.85rem 1rem;
    margin-bottom: 1.3rem;
}
.validation-summary-errors ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.3rem; }
.validation-summary-errors li { color: var(--fail); font-size: 0.85rem; }
.field-validation-error {
    display: block;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.02em;
    color: var(--fail);
    margin-top: 0.45rem;
}
.input-validation-error, .field__input.input-validation-error {
    border-color: var(--fail) !important;
    box-shadow: inset 0 0 0 1px var(--fail) !important;
}
/* TempData / status banners */
.alert { border-radius: var(--radius); padding: 0.85rem 1rem; margin-bottom: 1.3rem; font-size: 0.9rem;
    border: 1px solid var(--line); }
.alert--ok { border-color: transparent; background: var(--pass-wash); color: #1E5A40; border-left: 3px solid var(--pass); }
.alert--info { border-color: transparent; background: var(--signal-wash); color: var(--slate); border-left: 3px solid var(--signal); }

/* ---- note / requirements block (shared) ---- */
.note { border: 1px solid var(--line); border-left: 2px solid var(--signal); background: var(--signal-wash);
    padding: 0.8rem 1rem; border-radius: var(--radius); margin: 1.2rem 0; }
.note .anno { color: var(--slate); }
.note ul { list-style: none; padding: 0; margin: 0.4rem 0 0; display: grid; gap: 0.35rem; }
.note li { display: flex; align-items: center; gap: 0.5rem; font-size: 0.82rem; color: var(--slate); }
.note li svg { width: 14px; height: 14px; color: var(--signal); flex-shrink: 0; }