:root {
    --primary-color: #00ffd5;
    --secondary-color: #ff00ff;
    --background-color: #000000;
    --flip-shadow: rgba(0, 255, 213, 0.2);
    
    /* Fluid design - using clamp() for smooth scaling */
    --digit-size: clamp(60px, 8vw, 280px);
    --digit-width: clamp(50px, 6.5vw, 220px);
    --digit-height: clamp(75px, 10vw, 320px);
    --clock-gap: clamp(8px, 2.5vw, 40px);
    --number-gap: clamp(4px, 1.5vw, 20px);
    --separator-size: clamp(48px, 6.5vw, 224px);
    --card-gap: 2px;
    
    /* Control button sizes */
    --btn-padding: clamp(8px, 1.5vw, 12px) clamp(12px, 3vw, 24px);
    --btn-font-size: clamp(11px, 2vw, 16px);
    --btn-min-width: clamp(90px, 20vw, 160px);
}

/* ==========================================
   Light theme
   ========================================== */
body.light-theme {
    --primary-color: #00b8a3;
    --background-color: #ffffff;
    --flip-shadow: rgba(0, 184, 163, 0.2);
}

body.light-theme .bottom-card {
    border-top: 1px solid rgba(0, 184, 163, 0.3);
}

body.light-theme .switch-label.inactive {
    color: rgba(0, 184, 163, 0.4);
}

/* ==========================================
   Base styles
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: var(--background-color);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: 'Space Mono', monospace;
    overflow-x: hidden;
    transition: background-color 0.3s ease;
    margin: 0;
    padding: 0;
}

.clock-container {
    position: relative;
    width: 100%;
    max-width: 100vw;
    padding: clamp(10px, 2vw, 20px);
    box-sizing: border-box;
    transition: all 0.4s ease;
}

/* ==========================================
   Clock component styles
   ========================================== */
.clock {
    display: flex;
    gap: var(--clock-gap);
    align-items: center;
    justify-content: center;
    filter: drop-shadow(0 0 15px var(--flip-shadow));
    transition: gap 0.4s ease;
}

.number-group {
    display: flex;
    gap: var(--number-gap);
    transition: gap 0.4s ease;
}

.flipper {
    position: relative;
    width: var(--digit-width);
    height: var(--digit-height);
    background: var(--background-color);
    border-radius: 16px;
    perspective: 1000px;
    transition: all 0.4s ease;
    transform: translateZ(0);
    will-change: transform;
}

.top-card, .bottom-card {
    position: absolute;
    width: 100%;
    height: calc(50% - var(--card-gap) / 2);
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: var(--digit-size);
    line-height: var(--digit-height);
    font-weight: bold;
    color: var(--primary-color);
    background: var(--background-color);
    border: 2px solid var(--primary-color);
    overflow: hidden;
    transition: all 0.3s ease;
}

.top-card {
    top: 0;
    border-radius: 16px 16px 0 0;
    border-bottom: none;
    transform-origin: bottom;
    display: flex;
    align-items: flex-start;
    clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
    margin-bottom: var(--card-gap);
}

.bottom-card {
    bottom: 0;
    border-radius: 0 0 16px 16px;
    border-top: 1px solid rgba(0, 255, 213, 0.3);
    transform-origin: top;
    display: flex;
    align-items: flex-end;
    clip-path: polygon(0 0, 100% 0, 100% 100%, 0 100%);
    margin-top: var(--card-gap);
}

.separator {
    display: block;
    font-size: calc(var(--separator-size) * 0.8);
    color: var(--primary-color);
    text-shadow: 0 0 20px var(--primary-color);
    animation: pulse 2s infinite;
    margin: 0 clamp(-15px, -1.5vw, -10px);
    padding-bottom: 0.3em;
    transition: all 0.3s ease;
}

/* ==========================================
   Animation effects
   ========================================== */
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

@keyframes flipTop {
    0% {
        transform: rotateX(0deg);
        z-index: 2;
    }
    100% {
        transform: rotateX(-90deg);
        z-index: 0;
    }
}

@keyframes flipBottom {
    0% {
        transform: rotateX(90deg);
        z-index: 1;
    }
    100% {
        transform: rotateX(0deg);
        z-index: 2;
    }
}

/* Flip animation - basic */
.flipper.flip .top-card {
    animation: flipTop 0.4s ease-in;
    transform-origin: bottom;
}

.flipper.flip .bottom-card {
    animation: flipBottom 0.4s ease-out;
    transform-origin: top;
}

/* Seconds animation - fast (0.3s) */
.flipper.seconds-tens.flip .top-card,
.flipper.seconds-ones.flip .top-card {
    animation: flipTop 0.3s ease-in;
}

.flipper.seconds-tens.flip .bottom-card,
.flipper.seconds-ones.flip .bottom-card {
    animation: flipBottom 0.3s ease-out;
}

/* Minutes animation - medium (0.6s) */
.flipper.minutes-tens.flip .top-card,
.flipper.minutes-ones.flip .top-card {
    animation: flipTop 0.6s ease-in;
}

.flipper.minutes-tens.flip .bottom-card,
.flipper.minutes-ones.flip .bottom-card {
    animation: flipBottom 0.6s ease-out;
}

/* Hours animation - slow (0.8s) */
.flipper.hours-tens.flip .top-card,
.flipper.hours-ones.flip .top-card {
    animation: flipTop 0.8s ease-in;
}

.flipper.hours-tens.flip .bottom-card,
.flipper.hours-ones.flip .bottom-card {
    animation: flipBottom 0.8s ease-out;
}

/* Reduce animation complexity */
@media (prefers-reduced-motion: reduce) {
    .flipper.flip .top-card,
    .flipper.flip .bottom-card {
        animation-duration: 0.1s;
    }
}

/* ==========================================
   Control button styles
   ========================================== */
.controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: clamp(10px, 2vw, 20px);
    margin-top: clamp(20px, 4vw, 40px);
    flex-wrap: wrap;
}

.controls--panel {
    margin-top: 0;
    flex-direction: column;
    gap: 12px;
    display: flex;
    min-height: 140px;
}

/* Button base styles */
.btn {
    background: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    padding: var(--btn-padding);
    border-radius: 8px;
    font-family: 'Space Mono', monospace;
    font-size: var(--btn-font-size);
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 1px;
    min-width: var(--btn-min-width);
    white-space: nowrap;
}

.btn:hover {
    background: var(--primary-color);
    color: var(--background-color);
    box-shadow: 0 0 20px rgba(0, 255, 213, 0.5);
}

.btn:active {
    transform: scale(0.95);
}

.btn--panel {
    width: 100%;
    margin: 0;
    flex-shrink: 0;
}

/* Time format toggle switch styles */
.time-format-switch {
    display: flex;
    align-items: center;
}

.time-format-switch--panel {
    width: 100%;
    justify-content: center;
}

.switch-container {
    display: flex;
    align-items: center;
    gap: clamp(8px, 1.5vw, 12px);
}

.switch-label {
    font-family: 'Space Mono', monospace;
    font-size: var(--btn-font-size);
    font-weight: bold;
    color: var(--primary-color);
    text-transform: uppercase;
    letter-spacing: 1px;
    transition: all 0.3s ease;
}

.switch-label.active {
    color: var(--primary-color);
    text-shadow: 0 0 10px var(--primary-color);
}

.switch-label.inactive {
    color: rgba(0, 255, 213, 0.4);
}

.switch-track {
    position: relative;
    width: clamp(45px, 8vw, 60px);
    height: clamp(22px, 4vw, 30px);
    background: transparent;
    border: 2px solid var(--primary-color);
    border-radius: 15px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.switch-track:hover {
    box-shadow: 0 0 15px rgba(0, 255, 213, 0.3);
}

.switch-slider {
    position: absolute;
    top: 3px;
    left: 3px;
    width: clamp(14px, 3vw, 20px);
    height: clamp(14px, 3vw, 20px);
    background: var(--primary-color);
    border-radius: 50%;
    transition: all 0.3s ease;
    box-shadow: 0 0 10px rgba(0, 255, 213, 0.5);
}

.switch-track.active .switch-slider {
    transform: translateX(clamp(21px, 4.5vw, 28px));
}

/* ==========================================
   Hide seconds state styles
   ========================================== */
.clock-container.hide-seconds {
    --digit-size: clamp(100px, 12vw, 380px);
    --digit-width: clamp(80px, 10vw, 250px);
    --digit-height: clamp(120px, 15vw, 400px);
    --clock-gap: clamp(12px, 4vw, 60px);
    --number-gap: clamp(6px, 2vw, 30px);
}

.clock-container.hide-seconds .seconds-group,
.clock-container.hide-seconds .seconds-separator {
    display: none;
}

/* ==========================================
   Panel control system
   ========================================== */
.breadcrumb-btn {
    position: fixed;
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: var(--primary-color);
    border: none;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0, 255, 213, 0.3);
    transition: all 0.3s ease;
    z-index: 1000;
}

.breadcrumb-btn:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 20px rgba(0, 255, 213, 0.4);
}

.breadcrumb-btn svg {
    fill: var(--background-color);
}

.controls-panel-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 998;
}

.controls-panel-overlay.active {
    opacity: 1;
    visibility: visible;
}

.controls-panel {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: var(--background-color);
    border: 2px solid var(--primary-color);
    border-bottom: none;
    border-radius: 20px 20px 0 0;
    transform: translateY(100%);
    transition: transform 0.3s ease;
    z-index: 999;
    overflow-y: auto;
}

.controls-panel.active {
    transform: translateY(0);
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    border-bottom: 1px solid rgba(0, 255, 213, 0.2);
}

.panel-header h3 {
    margin: 0;
    color: var(--primary-color);
    font-family: 'Space Mono', monospace;
    font-size: 18px;
    font-weight: bold;
}

.panel-content {
    padding: 20px;
    min-height: 180px;
    box-sizing: border-box;
}

/* Light theme panel adaptation */
body.light-theme .controls-panel {
    border-color: var(--primary-color);
    box-shadow: 0 -4px 20px rgba(0, 184, 163, 0.1);
}

body.light-theme .breadcrumb-btn {
    box-shadow: 0 4px 12px rgba(0, 184, 163, 0.3);
}

body.light-theme .breadcrumb-btn:hover {
    box-shadow: 0 6px 20px rgba(0, 184, 163, 0.4);
}

/* ==========================================
   Responsive breakpoint system
   ========================================== */

/* Extra small screen: < 400px (target: 300px × 400px) */
@media (max-width: 399px) {
    .clock {
        flex-direction: column;
        gap: 5px;
    }
    
    .separator {
        transform: rotate(90deg);
        padding-bottom: 0;
    }

    .controls--main {
        display: none;
    }
    
    .breadcrumb-btn {
        display: flex;
    }
}

/* Small screen: 400px - 599px (target: 375px × 500px, 500px × 350px) */
@media (min-width: 400px) and (max-width: 599px) {
    .clock-container:not(.hide-seconds) {
        --digit-size: clamp(70px, 9vw, 280px);
        --digit-width: clamp(60px, 7vw, 220px);
        --digit-height: clamp(85px, 11vw, 320px);
        --clock-gap: clamp(10px, 2.5vw, 40px);
        --number-gap: clamp(5px, 1.5vw, 20px);
        --separator-size: clamp(55px, 7vw, 240px);
    }
    
    .controls--main {
        display: none;
    }
    
    .breadcrumb-btn {
        display: flex;
    }
    
    .controls--panel {
        gap: 15px;
    }
}

/* Medium screen: 600px - 899px (target: 768px × 400px) */
@media (min-width: 600px) and (max-width: 899px) {
    .clock-container:not(.hide-seconds) {
        --digit-size: clamp(90px, 11vw, 350px);
        --digit-width: clamp(80px, 9vw, 280px);
        --digit-height: clamp(110px, 13vw, 380px);
        --clock-gap: clamp(15px, 3.5vw, 55px);
        --number-gap: clamp(7px, 2.2vw, 28px);
        --separator-size: clamp(70px, 9vw, 300px);
    }
    
    .clock-container.hide-seconds {
        --digit-size: clamp(130px, 15vw, 450px);
        --digit-width: clamp(110px, 13vw, 360px);
        --digit-height: clamp(150px, 18vw, 480px);
        --clock-gap: clamp(20px, 6vw, 90px);
        --number-gap: clamp(10px, 3.5vw, 45px);
    }
    
    .controls--main {
        display: flex;
    }
    
    .controls--main .btn {
        padding: clamp(8px, 1vw, 12px) clamp(12px, 1.5vw, 16px);
        font-size: clamp(12px, 1.5vw, 14px);
        min-width: clamp(100px, 12vw, 140px);
    }
    
    .controls--main .switch-track {
        width: clamp(30px, 4vw, 40px);
        height: clamp(15px, 2vw, 20px);
    }
    
    .controls--main .switch-slider {
        width: clamp(10px, 1.5vw, 14px);
        height: clamp(10px, 1.5vw, 14px);
        top: clamp(2px, 0.25vw, 3px);
        left: clamp(2px, 0.25vw, 3px);
    }
    
    .controls--main .switch-track.active .switch-slider {
        transform: translateX(clamp(14px, 2vw, 18px));
    }
    
    .controls--main .switch-container {
        gap: clamp(6px, 1vw, 10px);
    }
    
    .breadcrumb-btn {
        display: none;
    }
    
    .controls {
        gap: clamp(12px, 2vw, 18px);
        flex-wrap: wrap;
        justify-content: center;
    }
}

/* Large screen: ≥ 900px (target: 800px × 400px, 1200px × 450px) */
@media (min-width: 900px) {
    .clock-container:not(.hide-seconds) {
        --digit-size: clamp(100px, 12vw, 400px);
        --digit-width: clamp(90px, 10vw, 320px);
        --digit-height: clamp(120px, 15vw, 450px);
        --clock-gap: clamp(16px, 4vw, 70px);
        --number-gap: clamp(8px, 2.5vw, 35px);
        --separator-size: clamp(80px, 10vw, 350px);
    }
    
    .controls--main {
        display: flex;
    }
    
    .controls--main .btn {
        padding: clamp(10px, 1vw, 14px) clamp(16px, 1.5vw, 20px);
        font-size: clamp(13px, 1.2vw, 16px);
        min-width: clamp(120px, 10vw, 160px);
    }
    
    .breadcrumb-btn {
        display: none;
    }
    
    .controls {
        gap: clamp(16px, 2.5vw, 24px);
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .clock-container {
        padding: clamp(15px, 2.5vw, 25px);
    }
}