:root {
    /* -------------------- Spacing Scale -------------------- */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-xxl: 4rem;

    /* -------------------- Typography Scale -------------------- */
   
    --font-size-xs: 0.75rem;    
    --font-size-sm: 0.875rem;   
    --font-size-md: 1rem;       /* body text */
    --font-size-lg: 1.25rem;    /* subheadings, card titles */
    --font-size-xl: 1.5rem;     /* section headings, h2 */
    --font-size-xxl: 2rem;      /* main headings, h1 */

    --line-height-xs: 1rem;
    --line-height-sm: 1.25rem;
    --line-height-md: 1.5rem;
    --line-height-lg: 1.75rem;
    --line-height-xl: 2rem;
    --line-height-xxl: 2.5rem;
    
/* ---------------------- Colours ----------------------- */

/* This vibrant palette was originally designed for my thesis project
   but never used there. Finally getting to see it in action here! */

/* Names according to Coolors.co: */

    --color-fire-engine-red: rgb(198, 40, 40);

    --color-folly:           rgb(255, 71, 94);
    --color-folly-90:        rgba(255, 71, 94, 0.9);

    --color-selective-yellow:rgb(244, 180, 0);
    --color-yellow-green:    rgb(138, 201, 38);
    --color-steel-blue:      rgb(25, 130, 196);

    --color-white:           rgb(255, 255, 255);
    --color-white-10:        rgba(255, 255, 255, 0.1);

    --color-seasalt:         rgb(250, 250, 250);

    --color-light-cyan:      rgb(224, 247, 250);
    --color-light-cyan-70:   rgba(224, 247, 250, 0.7);

    --color-silver:          rgb(189, 189, 189);
    --color-silver-30:       rgba(189, 189, 189, 0.3);

    --color-onyx:            rgb(60, 60, 60);
    --color-onyx-70:         rgba(60, 60, 60, 0.7);

    --color-smokey-black:    rgb(16, 12, 8);



    /* Color roles */
    --color-primary:        var(--color-steel-blue); 

    --color-secondary:      var(--color-folly);
    --color-secondary-90:   var(--color-folly-90);

    --color-accent:         var(--color-selective-yellow);
    --color-background:     var(--color-seasalt);
    --color-surface:        var(--color-silver);
    --color-surface-30:     var(--color-silver-30);

    --color-text-primary:   var(--color-onyx);
    --color-text-primary-70:var(--color-onyx-70);

    --color-text-muted:     var(--color-silver);

    --color-border-section: var(--color-silver-30);
    --color-border-card:    var(--color-silver);
    --color-border-input:   var(--color-silver);
    --color-border-input-focus: var(--color-primary);

    --color-error:          var(--color-fire-engine-red);
    --color-success:        var(--color-yellow-green);
    --color-warning:        var(--color-selective-yellow);
    --color-info:           var(--color-steel-blue);


    /* ------------------------ Shadows ----------------------- */

    --shadow-sidebar: 2px 0 8px var(--color-onyx-70);

    --shadow-section: 0 2px 8px var(--color-border-section);

    --shadow-card-sm: 0 1px 4px var(--color-border-card);
    --shadow-card-md: 0 4px 12px var(--color-border-card);
    --shadow-card-lg: 0 8px 24px var(--color-border-card);

    --shadow-input: 0 0 0 2px var(--color-border-input-focus);
    
    
    /* ------------------------ Text shadows ----------------------- */
    --text-shadow-md-sb: 0 2px 4px var(--color-smokey-black);
    --text-shadow-md-wh: 0 2px 4px var(--color-white);


    /* -------------------- Button default vars -------------------- */
    --button-bg: var(--color-primary);
    --button-hover: var(--color-secondary);

    /* -------------------- Header default vars -------------------- */
    --main-header-gradient: linear-gradient(180deg, var(--color-primary),var(--color-text-primary-70) 95%);
    --page-header-gradient: linear-gradient(135deg, var(--color-primary),var(--color-secondary));

}

/* ---------------------- Themes ----------------------- */

/* Day theme */
[data-theme="day"] {
    --main-header-gradient: linear-gradient(
        180deg, 
        var(--color-primary), 
        var(--color-text-primary-70) 95%
    );
    --page-header-gradient: linear-gradient(
        135deg, 
        var(--color-primary), 
        var(--color-secondary)
    );
    --button-bg: var(--color-primary);
    --button-hover: var(--color-secondary);
}

/* Night theme */
[data-theme="night"] {
    --main-header-gradient: linear-gradient(
        180deg, 
        var(--color-smokey-black) 0%, 
        var(--color-onyx) 40%, 
        var(--color-onyx-70) 100%
    );
    --page-header-gradient: linear-gradient(
        135deg,
        var(--color-onyx), 
        var(--color-folly), 
        var(--color-selective-yellow));
    --button-bg: var(--color-folly);
    --button-hover: var(--color-fire-engine-red);
}

/* -------------------- Reset & Base -------------------- */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    display: flex;
    flex-direction: row;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    color: var(--color-text-primary);
    background-color: var(--color-background);
}

/* ------------------ Main Header (Sidebar) ------------------ */

.main-header{
    display: flex;
    flex-direction: column;
    flex: 0 1 20%;
    align-self: flex-start;
    padding: var(--space-md);
    background: var(--main-header-gradient);
    box-shadow: var(--shadow-sidebar);
    color: var(--color-white);
    min-height: 100vh;
    position: sticky;
    top: 0;
}

/* Collapsed Sidebar */
.main-header.collapsed {
    flex: 0 0 4rem;
    padding: var(--space-xs);
}

/* -------------------- Sidebar Toggle Button -------------------- */

button.sidebar-toggle {
    display: flex;
    flex-direction: row;
    padding: var(--space-xs);
    border: none;
    outline: none;
    background: none;
    align-items: center;  
    gap: var(--space-xs);
    cursor: pointer;
    color: var(--color-white);
    width: 100%;
}

/* Hide text when sidebar is collapsed */
.main-header.collapsed button.sidebar-toggle .site-nav-label {
    display: none;
}

/* Sidebar toggle SVG */
.sidebar-toggle svg {
    width: 3rem;
    height: 3rem;
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}

/* Sidebar toggle SVG paths */
.sidebar-toggle svg path {
    stroke: currentColor;
    stroke-width: 2;
    stroke-linecap: round;
    stroke-linejoin: round;
    fill: none;
}

/* ------------------ Theme Toggle Button ------------- */

#theme-toggle {
    display: flex;
    margin: var(--space-sm) 0;
    padding: var(--space-xs);
    width: 100%;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    border: 1px solid var(--color-white-10);
    border-radius: 12px;
    align-items: center;
    justify-content: center;
    color: var(--color-white);
    cursor: pointer;
    font-size: var(--font-size-sm);
    font-weight: 500;
    transition: all 0.25s ease;
}

#theme-toggle:hover {
    background: var(--color-secondary);
    border-color: var(--color-secondary);
    box-shadow: var(--shadow-card-sm);
    transform: scale(1.05);
}

/* -------------------- Navigation -------------------- */

.site-nav{
    display: flex;
    flex-direction: column;
    margin-top: var(--space-sm);
}

.site-nav a {
    display: flex;
    padding: var(--space-xs);
    align-items: center;
    font-size: var(--font-size-lg);
    font-weight: 500;
    color: var(--color-white);
    text-decoration: none;
    transition: color 0.2s ease, transform 0.2s ease;
    gap: 0.75rem;
}

/* Divider */
.site-nav a + a {
    border-top: 1px solid var(--color-white-10);
}

/* Hover Effect */
.site-nav a:hover {
    color: var(--color-secondary);
    transform: translateX(2px);
}

/* SVG */
.site-nav svg {
    flex-shrink: 0;
    width: 1.5rem;
    height: 1.5rem;
    fill: none;
    stroke: currentColor;
    stroke-width: 1.8;
}

/* Center icons when sidebar collapsed */
.main-header.collapsed .site-nav a {    
    justify-content: center;
    padding: var(--space-xs 0);
}

/* Hide text when sidebar collapsed */
.main-header.collapsed .site-nav a .nav-label {
    display: none;
}

/* ---------------------- Layout ----------------------- */

.right-wrapper{
    display: flex;
    flex-direction: column;
    flex: 1;
}

main {
    display: flex;
    flex-direction: column;
    flex: 1;
    padding: var(--space-xl);
}

footer{
    flex: 1;
    flex-direction: column;
    padding-left: var(--space-md);
}

/* ---------------- Section & Headers ------------------- */

section {
    margin: var(--space-md) 0;
}

section h2 {
    margin-bottom: var(--space-sm);
    font-size: var(--font-size-xl);
    color: var(--color-primary);
}

/* Page header */

.page-header {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: flex-start;
    width: 100%;
    border-radius: 8px;
    box-shadow: var(--shadow-card-md);
    background: var(--page-header-gradient);
    padding: var(--space-xxl) var(--space-md);
    margin-bottom: var(--space-xl);
    gap: var(--space-sm);
    color: var(--color-white);
}

.page-header h1 {
    font-size: var(--font-size-xxl);
    margin-bottom: var(--space-sm);
}

.page-header p {
    color: var(--color-white);
    font-size: var(--font-size-md);
}

/* -------------------- Cards -------------------- */
.card-grid{
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--space-md);
}

.card {
    padding: var(--space-md);
    border: 1px solid var(--color-border-card);
    border-radius: 8px;
    background-color: var(--color-surface-30);
    box-shadow: var(--shadow-card-sm);
    transition: box-shadow 0.2s ease, border-color 0.2s ease;
}

.card:hover {
    box-shadow: var(--shadow-card-md);
    border-color: var(--color-border-card);
}

.card-title {
    font-size: var(--font-size-lg);
    margin-bottom: var(--space-sm);
    color: var(--color-primary);
}

.card-text {
    color: var(--color-text-primary-70);
    line-height: var(--line-height-md);
    margin-bottom: var(--space-sm);
}

.card-meta {
    font-size: var(--font-size-sm);
    color: var(--color-secondary);
    margin-bottom: var(--space-xs);
    font-weight: 500;
}

.card-list {
    margin: var(--space-sm) 0;
    padding-left: var(--space-md);
}

.card-list li {
    color: var(--color-text-primary-70);
    line-height: var(--line-height-md);
    margin-bottom: var(--space-xs);
    list-style-type: disc;
}

.card-actions {
    display: flex;
    gap: var(--space-sm);
    margin-top: var(--space-sm);
}

/*-------------------- Buttons ---------------------*/

.button {
    display: inline-block;
    padding: var(--space-xs) var(--space-sm);
    background-color: var(--button-bg);
    color: var(--color-white);
    text-decoration: none;
    border-radius: 4px;
    font-size: var(--font-size-sm);
    transition: 
        transform 0.15s ease,
        box-shadow 0.15s ease,
        background-color 0.2s ease;
}

.button:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-card-sm);
    background-color: var(--button-hover);
}

.button:active {
    transform: translateY(0);
    box-shadow: none;
}

.button-fire {
    display: inline-block;
    position: relative;
    padding: var(--space-xs) var(--space-md);
    background: linear-gradient(
        135deg,
        var(--color-folly), 
        var(--color-selective-yellow));
    color: var(--color-smokey-black);
    border-radius: 4px;
    font-size: var(--font-size-sm);
    font-weight: 500;
    letter-spacing: 0.5px;
    transition: transform 0.15s ease,
                filter 0.15s ease,
                box-shadow 0.15s ease;
    cursor: pointer;
}

.button-fire:hover {
    transform: translateY(-1px);
    box-shadow: var(--shadow-card-sm);
    filter: brightness(1.10);
}

.button-fire:active {
    transform: translateY(0);
    box-shadow: none;
    filter: brightness(0.95);
}

/* --------------------- Home Page ----------------------- */

.home-intro {
    margin-bottom: var(--space-xxl);
    padding: var(--space-lg);
    border-radius: 8px;
    background-color: var(--color-surface-30);
    box-shadow: var(--shadow-card-sm);
    color: var(--color-text-primary-70);
}

.home-intro p {
    font-size: var(--font-size-md);
    line-height: var(--line-height-md);
    margin-bottom: var(--space-md);
}


/* -------------------- Projects Page -------------------- */

/* Responsive adjustments */
@media (min-width: 768px) {
    .card-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .card-grid {
        gap: var(--space-lg);
    }
    
    .card {
        padding: var(--space-lg);
    }
}

/* --------------------- About Page --------------------- */

.about-wrapper {
    display: flex;
    flex-direction: column;
    gap: var(--space-md);
}

.about-section {
    display: flex;
    flex-direction: column;
    margin: 0;
    padding: var(--space-md);
    border-radius: 8px;
    border: 1px solid var(--color-border-section);
    background-color: var(--color-surface-30);
    box-shadow: var(--shadow-card-sm);
    gap: var(--space-xs);
}

.about-section p.card-meta a,
.about-section p.card-meta a:visited {
    text-decoration: none;
}

.about-section p.card-meta a:hover {
    text-decoration: underline;
}

.about-section ul {
    display: flex;
    flex-direction: column;
    padding-left: var(--space-sm);
    list-style:circle;
    gap: var(--space-xs);
}

.about-section ul li {
    color: var(--color-text-primary-70);
}

/* -------------------- Contact Page -------------------- */

.contact-section {
    padding: var(--space-md);
    border-radius: 8px;
    border: 1px solid var(--color-border-section);
    background-color: var(--color-secondary-90);
}

.contact-section h2 {
    color: var(--color-white);
    text-shadow: var(--text-shadow-md-sb) ;
}

.contact-section p {
    color: var(--color-white);
    margin-bottom: var(--space-sm);
}

.contact-section ul li {
    color: var(--color-white);
    list-style: none;
}

.contact-section a {
    color: var(--color-smokey-black);
    text-shadow: var(--text-shadow-md-wh);
    text-decoration: none;
}

.contact-section form {
    display: flex;
    flex-direction: column;
}

.contact-section label {
    display: block;
    margin-bottom: var(--space-xs);
    font-size: var(--font-size-md);
    font-weight: 600;
    color: var(--color-white);
}

.contact-section input,
.contact-section textarea {
    margin-bottom: var(--space-md);
    padding: var(--space-sm);
    border: 1px solid var(--color-border-input);
    border-radius: 6px;
    font-size: var(--font-size-md);
    width: 100%;
    background-color: var(--color-white);
    color: var(--color-text-primary);
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.contact-section input:focus,
.contact-section textarea:focus {
    border-color: var(--color-border-input-focus);
    box-shadow: var(--shadow-input);
}

.contact-section textarea {
    resize: vertical;
    min-height: 10rem;
}

.contact-section .button-fire {
    border: 1px solid;
    border-color: var(--color-white);
}

.contact-success {
    color: var(--color-success);
    margin-top: var(--space-sm);
}

.contact-error {
    color: var(--color-error);
    margin-top: var(--space-sm);
}